Class 7

West Bengal Board Class 7 Text Book Solutions WBBSE

• West Bengal Board Class 7 Maths Book Solutions
• West Bengal Board Class 7 Science Book Solutions
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• West Bengal Board Class 7 History Book Solutions
• West Bengal Board Class 7 Bengali Book Solutions
• West Bengal Board Class 7 English Book Solutions
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WBBSE Solutions

Detailed explanations in West Bengal Board Class 8 Science Book Solutions Chapter 9 Endocrine System and Adolescence offer valuable context and analysis.

WBBSE Class 8 Science Chapter 9 Question Answer – Endocrine System and Adolescence

1. Read the stories of page numbers 228-229, then fill up the chart: (See Text book page no. 234)

Story number	Hormone causing the incident due to hypo/hyper secretion
1.	Testosterone hormone
2.	Adrenalin hormone
3.	Somatotrophic hormone
4.	Insulin
5.	Thyroid stimulating hormone

2. Name the hormones which are responsible for the following symptoms. (See Text Book page no. 234)

3. Discuss in groups and enlist the physical and mental changes you have undergone in your growing stage, just as Phatik. (Page no. 235)

Physical changes	Mental changes
Body is growing rapidly-in length and in size. Mustache is appearing, Softness of childhood and sweet charm of voice is disapearing.	Mind has become restless, it is impossible to concentrate on any work. Feel embarrassed.

(Page no. 236)

1. Just as Phatik loved to play and do household jobs, you also love to do some activities. What do you like to do?
Answer:
I like to do the work that are done by elders.

2. How do you feel to be praised for your performance?
Answer:
I feel very pleased and happy.

3. How do you feel to be criticised for your performance?
Answer:
I feel as harmed and apologetic.

4. Did you feel the same even in your childhood?
Answer:
No.

5. What are the changes you have noticed in yourself as you grew up?
Answer:
I am increasing in height, mind is becoming restless.

(Page no. 237)

1. Which hormones help to make rapid physical changes during adolescent age?
Answer:
Estrogen and testosterone.

2. Which endocrine gland releases- these hormones?
Answer:
Gonad gland.

(Page no. 238)

Read the above 2 stories. Then discuss with your friends and answer the following questions —

1. Which hormones from which endocrine glands are responsible for Raju, Subho and Tumpa’s condition?
Answer:
Pituitary gland.

2. How do you tjiiak Raju and Subho can improve their condition?
Answer:
Their condition will improve when they will be a fully grown man.

3. What can Tumpa do to improve her condition?
Answer:
She will have to take proper care of her health, for this she may consult a doctor.

(Page no. 239)

What are the behavioural changes taking in 13-14 year old child?
1. short-tempered
2. busting into tears for a slight cause
3. fight with others.
4. show interest in doing any kind of work.
5. to feel jealous.
6. tell lies
7. addiction to watch TV or playing.

What should be done if you notice such behavioural problems?
Answer:
We should try to control ourselves.

1. How did you like the above two stories?
Answer:
The stories makes us aware of the risky behaviour during adolescence.

2. Who was responsible for burning Ali’s right hand?
Answer:
Ali’s behaviour was responsible.

3. What should Ali have done?
Answer:
Ali should not have taken the risk of bursting crackers in his own hand.

4. Who is responsible for Bablu’s flight?
Answer:
Bablu himself is responsible, as he feared that he might offend Montu da if he disobeys him.

5. What should Bablu have done?
Answer:
Bablu should not have gone to bring cigarettes for Montu da.

Class 8 Science Chapter 9 Question Answer West Bengal Board – Endocrine System and Adolescence

Multiple Choice Questions & Answers : (1 mark for each question)

Question 1.
Hypo-secretion of thyroxin is responsible for —
i) the growth of our muscles
ii) reduced power of heart
iii) rough skin
iv) Moon face
Answer:
iii) rough skin

Question 2.
A mixed gland is —
i) Pituitary gland
ii) Pancreatic gland
iii) both of the glands
iv) none of the glands
Answer:
ii) Pancreatic gland.

Question 3.
Adrenal gland is present over —
i) kidney
ii) lungs
iii) heart
iv) liver
Answer:
i) Kidney.

Question 4.
Glucose increases in blood due to —
i) estrogen
ii) testosterone
iii) Insulin
iv) Thyroxine
Ans:
iii) Insulin

Question 5.
According to WHO adolescence age is between —
i) 5-7 years
ii) 9-12 years
iii) 10-49 years
iv) 13-20 years
Answer:
iii) 10-19 years

Question 6.
In male moustache and beard occur due to the impact of —
i) Progesterone
ii) Testosterone
iii) insulin
iv) thyroxine
Answer:
ii)Testosterone

Question 7.
Testis is present in —
i) male body
ii) female body
Answer:
i) male body

Question 8.
Adrenalin hormone controls our—
i) glucose level
ii) emergency actions
iii) growth
iv) body temperature
Answer:
iv) body temperature

Question 9.
Somatotrophic Hormone is responsible for –
i) swelling of glands
ii) unnatural growth
iii) glucose comes out through urine
iv) face becomes rounded
Answer:
ii) unnatural growth

Question 10.
Insulin is responsible for —
i) swelling of glands
ii) unnatural growth
iii) glucose comes out through urine
iv) face becomes rounded
Answer:
iii) glucose comes out through urine

State whether True or False : (1 mark for each question)

1) Adrenal gland look like triangle is present over each kidney.
2) Adrenanil hormone is anti-diabetic hormone.
3) Estrogen is secreted from the female body.
4) The name of the reproductive gland in the female body is testis.
5) Estrogen and testosterone become active after a specific age.
6) During hyper-secretion, the thyroid gland squeezes.
7) The tendency of infection increases due to the increase of blood sugar.
8) Somatotrophic Hormone is called emergency hormone.
9) The age group 30-45 years are denoted as adolescent age.
10) WHO has identified ten Core Generic Life skills.
Answer:
1) true
2) false
3) true
4) false
5) true
6) false
7) true
8) false
9) false
10) true

Fill in the blanks : (1 mark for each question)

1) The different changes that occur from our birth, in mind and body is controlled by ………………….
2) After the completion of the work, the hormone is ………………….
3) …………………. play the vital role to control our emotional feelings like feeling good, depressed, crying and smiling etc …………………..
4) …………………. juice secretes from gestric glands.
5) …………………. gland is called master gland.
6) Dwarfism occurs due to Hypo-secretion of …………………. Hormone
7) Thyroxine is secreted from …………………. gland.
8) In hypo-secretion of thyroxine hormone growth of the child is ………………….
9) The …………………. is situated in the anterior position of our neck.
10) …………………. maintain the glucose balance in the blood.
11) Insulin is called hormone.
12) …………………. hormone controls our systolic and diastolic power of our heart.
13) …………………. and …………………. are called gonad.
14) …………………. is secreted from the testis gland.
15) The gland which Bas both endocrine and exocrine cells are …………………. gland.
16) Vasopressin secretes from …………………. gland.
17) …………………. hormone controls our different mental conditions like fear, conflict and fight responses.
18) During adolescence, ……………. and …………..occur in male due to the impact of testosterone hormone.
19) Teenage can also be termed as ………………….
20) Uncontrolled expression of happiness, anger or sorrow affects our …………………. and …………………. health.
Answer:
1) hormones
2) destroyed
3) hormones
4) gastric.
5) pituitary
6) somatotrophic
7) thyroid
8) restricted
9) larynx
10) insulin
11) anti-diabetic
12) adrenalin
13) ovary, testis
14) testosterone
15) mixed
16) pituitary
17) adrenalin
18) moustache, beard
19) adolescence
20) physical, mental.

Very Short Questions & Answers : (1 mark for each question)

Question 1.
Which is the main part of our body?
Answer:
The main part of our body is brain.

Question 2.
Where does Hormone originate?
Answer:
Hormone originates from different types of cell clusters or glands present in our body.

Question 3.
Where Pituitary gland is found?
Answer:
Pituitary gland is found in the base of our brain.

Question 4.
Name two hormones that secret from pituitary gland.
Answer:
Somatotrophic hormone. Thyroid stimulating hormone.

Question 5.
What is the function of pituitary gland?
Answer:
It controls different important physiological functions of our body.

Question 6.
Which hormone is called growth hormone?
Answer:
Somatotrophic hormone is called growth hormone.

Question 7.
Write a name of mixed gland.
Answer:
Pancreatic gland.

Question 8.
What happens due to hyper-secretion of Somatotrophic Hormone.
Answer:
Hyper-secretion causes increase in the length of bone, the height becomes 7-8 feet.

Question 9.
What happens due to Hypo-secretion of growth hormone?
Answer:
The height of an adult will become 3 feet and he will look like a child.

Question 10.
What happens when there is hyper-secretion of Thyroid stimulating hormone?
Answer:
The thyroid gland bulges out. As a result the neck becomes thicker.

Question 11.
Which hormone helps to increase the heart rate?
Answer:
Thyroxine helps to increase the heart rate.

Question 12.
Name two hormones that secrete from Pancreatic gland.
Answer:
Insulin and glucagon.

Question 13.
Which, hormone is called anti-diabetic?
Answer:
Insulin.

Question 14.
Which hormone is termed as emergency hormone?
Answer:
Adrenalin hormone.

Question 15.
Hypo-secretion of which hormone causes diabetes?
Answer:
Insulin causes diabetes.

Question 16.
Where Adrenal gland occurs?
Answer:
Like a triangle Adrenal gland is present over each kidney.

Question 17.
What is the name of the reproductive gland in female body?
Answer:
Overy.

Question 18.
Which hormones secrete from ovary?
Answer:
Estrogen and Progesterone.

Question 19.
What is the name of the reproductive gland in male body?
Answer:
Testis is the name of the reproductive gland in male body.

Question 20.
Which hormones secrete from testis?
Answer:
Testosterone.

Question 21.
Which is the smallest Endocrine gland?
Answer:
Pituitary gland.

Question 22.
Due to which hormone moustache and. bear occur in male body?
Answer:
Testosterone.

Question 23.
What is adolescence?
Answer:
The period between childhood and youth is called teenage. Teenage can also be termed as adolescence.

Question 24.
Which age has been marked by WHO as adolescent age?
Answer:
WHO has marked the age group 10-19 years as adolescent age.

Question 25.
Which hormone is related with diabetes mellitus? from where this hormone secretes?
Answer:
Insulin is related with diabetes mellitus. Insulin secretes from Pancreas.

Question 26.
If any one is afraid which hormone secretes from which gland?
Answer:
To control mental condition like fear Adrenalin hormone secretes front Adrenal gland.

Short Questions & Answers : (2 marks for each question)

Question 1.
What is hormone?
Answer:
Hormone is a chemical matter carried out through the blood. They may be produced in out body according to the need, probable be for only a second. Again, some hormones-are present in the blood throughout our life.

Question 2.
What is Exocrine gland?
Answer:
Chemical secreted from the gland passes from one place to another through a duct. This type of gland is termed as Exocrine gland, such as saliva from salivary gland.

Question 3.
What is Endocrine gland?
Answer:
Some other glands which have no duct mixes the secreted substance directly With the blood. Blood takes these hormones to their target cell. These glands are termed as Endocrine glands, such as Thyroid gland.

Question 4.
What is Receptor?
Answer:
After getting proper order, the hormone is produced in its proper position and then it reaches the proper target. That target is called Receptor.

Question 5.
How many types of co-ordination occurs in our body?
Answer:
Two types of co-ordination occur in our body —

• Nervous co-ordination,
• co-ordination through chemical-reaction.

Question 6.
What is mixed gland?
Answer:
There is another type of gland which are both endocrine and exocrine cells. They are mixed glands.

Question 7.
Where from Estrogen secretes? Write one of its function.
Answer:
Estrogen secretes from the reproductive gland ovary of female body. Estrogen helps to complete growth of the female body by increasing her bones and muscles.

Question 8.
Write two important characteristics of hormone.
Answer:

• Hormones are secreted from their source directly into the blood.
• They regulate the physiological process by chemical means. They affect the enzyme systems of the body.

Question 9.
Why pituitary gland is called master gland?
Answer:
Pituitary gland is called the master gland because it controls the growth and working of all other endocrine glands. Pituitary gland controls different important physiological functions of our body.

Long Questions & Answers : (3 marks for each question)

Question 1.
Explain the vital role that hormone plays in our body.
Answer:
The hormone plays a vital role in our body growth, metabolism, immunity, blood pressure, urin production, sweat production and also maintaining the heart system. Hormones also play the vital role to control our emotional feelings like feeling good, depressed, crying and smiling etc.

Question 2.
Why hormones are called chemical messenger?
Answer:
The activities in our body are highly complex and they need to be so regulated that every activity takes place at a proper time and in a correct sequence. Though this kind of regulation is done to some extent by the nervous system, another type of co-ordination occurs through chemical reaction. Hormones act as a chemical messenger in this type of co-ordination, so hormones are called chemical messenger.

Question 3.
Write some functions of Thyroxine.
Answer:

• This hormone helps to increase the heart rate.
• It helps to produce energy in our body.
• It helps to increase the use of oxygen in the cells of our body.
• It also helps to increase the muscle and bone of our body.

Question 4.
Why Adrenalin hormone is called emergency hormone?
Answer:
Adrenal gland secretes adrenalin during diferent emergency situation of our body. It prepares our body to combat with different emergency situation. So this hormone is termed as emergency hormone.

Question 5.
Write two functions of Somatotrophic hormone.
Answer:

• It promotes the growth of our muscles and bones.
• This hormone exerts some specific effect on protein metabolism by reducing protein metabolism and by reducing protein catabolism.

Question 6.
Where Pituitary gland exists? flow many lobes it lias?
Answer:
The pituitary gland is found in the base of our brain. It has two lobes. The upper part is called Anterior Pituitary and the lower is called Posterior Pituitary.

Question 7.
Write functions of Adrenalin hormone.
Answer:

• This hormone increases our respiratory rate.
• It controls our body temperature.
• It even controls our systolic and diastolic power of our heart.
• It controls urine production.
• It also controls our different mental conditions like fear, conflict and fight or flight responses.

Question 8.
What disorders occur due to hyper-secretion and hypo-secretion of Adrenalin hormone.
Answer:
During the hypersecretion of Adrenalin hormone our face become rounded and swollen, this state is called Moon face. The facial skin becomes rough and pale. Hairy out growth occurs in the woman. The healing of wounds takes time. Poor metabolism and weakness in the muscles occur during hypo-secretion of Adrenalin hormone.

Question 9.
What disorders occur due to hyper-secretion and hypo-secretion of Thyroxine hormone?
Answer:
Hyper-secretion of Thyroxine hormone creates bulging in thyroid gland. Sometimes it seems the eyes are coining out. It creates differences in blood pressure.

Hypo-secretion of Thyroxine hormone restricts the growth of the child. The swelling of abdomen occurs. The muscles become weak. The tongue comes out. The saliva secretion occurs. Among the adult, hypo-secretion of thyroxin creates rough skin.

Question 10.
What is life skill education? Name the ten core Generic life skills identified by WHO.
Answer:
Life skill education is a special behaviour which helps us to identify the various needs and provides strength to face challenges successfully. The ten Core Genesic life skills identified by WHO are —

• Self-awareness
• Critical thinking
• Decision making,
• Problem-solving
• Creative thinking
• Inter personal communication
• Interpersonal relationship
• Empathy
• Stress management
• Emotional management.

Detailed explanations in West Bengal Board Class 7 Science Book Solutions Chapter 4 Role of Substances in Environment offer valuable context and analysis.

WBBSE Class 7 Science Chapter 4 Question Answer – Role of Substances in Environment

(Page no. 101)

Write the names of two metallic and four non-metallic elements in the blank space.
Answer:
Metallic elements Iron, Copper.
Non ntetallic elements Graphite, Hydrogen, Sulpher, Phosphorus.

Write the names of three non-metals that are more abundant in human body than in earth curst.
Answer:
(1) Oxygen, (2) Carbon, (3) Nitrogen

We can see from the table that about 97% of the total mass of human hody can be attributed to the combined mass of four elements. Can you identify them?
Answer:

1. Oxygen
2. Carbon
3. Nirtrogen
4. Hydrogen.

(Page no. 105)

mention the different parts of plants that we take as food.
Answer:

Parts of a plant body	Name of the plant
Underground root	Beat root, carrot, radish
Underground or normal stem	Potato, sweet potato.
Flower	Cauliflower, Pumkin flower.
Fruit	Mango, Apple

We take different fruits of different plants. Do they have the same taste? Share your previous experience with your friends and complete the following table :
Answer:

Name of familiar fruits	Their taste
Lemon	Sour
Ripe Mango	Sweet
Pine Apple	Sweet
Orange	Sour and Sweet
Apple	Sweet

With the help of your teacher prepare a sugar solution, salt solution and vinegar solution.Try to recognise them by taking their taste.
Answer:

Taste of the sample solution	Sample seems to be
Sweet	Sugar solution
Salty	Salt solution
Sour	Vinegar solution

(Page no. 107)

We use acids for various purposes. Do you know any such use of acid? Discuss among yourselves and write.
Answer:

Which substance	Used in which field
Juice of lemon (citric acid)	To turn milk into posset.
Muriatic acid	To clean toilets.
Vinegar	To store fish and meat.

Now notice whether any change occurs or not :
Answer:

Prepare a solution of baking soda with drinking water in a glass with the help of your teacher.

Now taste this solution along with previously prepared vinegar solution (or filtered lemon juice) and a little of lime water. Note down your observation.
Answer:

Which solution	How does it taste
Vinegar solution	Sour
Baking soda solution	Bitter and soapy feel.
Lime water	Bitter and soapy feel.

(Page no. 108)

If you know about any other uses of lime or any other base then write down after discussion with your friends.
Answer:

Name of the substance	Its use
Sodium Hydroxide	Manufacture of soap
Magnesium Hydroxide	As an antacid. [neutralizes acidity]

(Page no. 109)

Take hibiscus petal juice into seperate glasses. Add vinegar in one glass and lime water in another glass. Note down the observations.
Answer:

Vinegar is an acid. It changes the colour of hibiscus petal juice from pink to green. Again lime water is a basic substance. It changes the colour of hibiscus petal juice from pink to red. Here Hibiscus petal juice serves as an indicator.

(Page no. 111)

Take some indicators like litmus, phenolphthalein or methyl orange. Note the change in their colourwhen they are added to various solutions, Write down your observation in the following table :
Answer:

If you know about any example of such type of neutralization reaction in your daily life around your house, share it among yourselves and write it down.
Answer:

(Page no. 114)

Test the following solutions with a pH paper and see whether they have a pH equal to greater than or less than 7.
Answer:

(Page no. 117)

You need a few pieces red and blue litmus papers and some samples to identity. Then like the previous experiments, test the samples with red and blue litmus papers and fill up the following table :
Answer:

(Page no. 118)

For proper functioning of our body, the right balance of acidity and basicity must be maintained. Different fluids of our body have different extents of acidic and basic nature (pH). Can you tell anything about the nature of those fluids mentioned below?
Answer:

(Page no. 120)

Carefully observe the two pictures of the two principal sources of our food.
1. Plant source and 2. Animal source
Make a small chart about the food you generally take from these two origins.
Answer:

In how many ways we eat these foods?
Answer:
1. raw
2. roasted
3. boiled
4. eat after cooking.

(Page no. 122)

Almost 47 compounds have been reported to be present with the sea salt among which 7 compounds are important. These are –
Answer:

(Page no. 129)

How can salt be used in following cases ?
Answer:

Problem	Use of common salt
In your toothache	You must rub gum with salt
One day when you suffered suddenly from vomiting and diarrhoea	You must take a small amount of solution made from a little salt and sugar at rugular intervals
In your throat pain	You must gargfe with mild hot water mixed with salt
A leech bites in your leg	You must use salt on the biting spot to stop bleeding
Preservation of ripe tamarind	You must add salt with tamarind
If a symptom like low blood prseeure is found in someone	He must take salty food to increase blood pressure

(Page no. 129)

Discuss with your friends and prepare a list of the things you use from morning to night. Mention whether these materials some from natural, synthetic or manmade sources.
Answer:

(Page no. 131)

Sometimes sit-and-draw competitions are held in your locality or in your school. The equipments required for this purpose are shown below. Write their names and then write after discussion whether they are natural, processed or synthetics.
Answer:

(Page no. 132)

What other things can be made from these synthetic materials.
Answer:

Name of the synthetic material	Its use cups, boxes, bottles, containers, helmets, electronic goods
Plastic	pipes, rain coat, shoes, automobile and health care goods
PVC	water pipe and tank, bottles, drums, iceboxes, toys, ropes
Polyethylene	fancy bags, seatcover, shoes, cushions etc.
Rexin	Its use cups, boxes, bottles, containers, helmets, electronic goods

(Page no. 135)

Write the names of the synthetic materials used as a body soap, washing soap or for other activities mentioned below.
Answer:

Use	Materials
Bathing and washing	bathing soap
Clesning hair	shampoo
Washing and cleaning utensils	bar soap or liquid soap

(Page no. 137)

The picture of some of your familiar things below. Can you identify them. Write their uses.
Answer:

Name of the substance	Uses
a. Vaseline	mosturises body, heal minor skin scratches and burns
b. Shampoo	used to clesnse hair
c. Lipstick	used by women to cslour lips
d. Toothpaste	used to clean and maintain nealth of the teeth
e. Body spray	They make you smell ‘extra nice’.
f. Powder	makes skin smooth, used to set makeup
g. Nail polish	to colour nails
h. Tips	used by women for beautification of face

(Page no. 137)

Make a list of colourful objects, both organic and inorganic, around you and try to know about the source of their colours with the help of your teacher.
Answer:

Objects	Source of colour
Carrot	Organic
Turmeric	Organic
Petals of rose or marigold	Organic
Coloured plastic tumbler	Inorganic

Class 7 Science Chapter 4 Question Answer West Bengal Board – Role of Substances in Environment

Multiple Choice Questions & Answers : (1 mark for each question)

Question 1.
The most abundant element found in human body is–
i) Aluminium
ii) Silicon
iii) Oxygen
iv) Carbon
Answer:
iii) Oxygen

Question 2.
The water content in human body is near about–
i) 60 %
ii) 70 %
iii) 90 %
iv) 80 %
Answer:
i) 60 %

Question 3.
If there is increased quantity of fat in a body then water content is-
i) less
ii) exceeds
iii) remain the same
Answer:
i) less

Question 4.
Next to oxygen, the most important requirement for our survival is
i) air
ii) light
iii) water
Answer:
iii) water

Question 5.
Iron is an essential component of-
i) bones
ii) red blood cells
iii) nerve
iv) skin
Answer:
ii) red blood cells

Question 6.
The major constituent of bone is a phosphate of-
i) iron
ii) sodium
iii) magnesium
iv) calcium
Answer:
iv) calcium

Question 7.
Energy required for germination of the seed comes from-
i) protein
ii) water
iii) carbohydratrates
Answer:
iii) carbohydrates

Question 8.
Breakdown of lipids in a cell gives-
i) strength
ii) energy
iii) stimulation
Answer:
ii) energy

Question 9.
The fluid secreted from the body of an ant is-
i) acid
ii) base
iii) salt
Answer:
i) acid

Question 10.
Water in nature is-
i) acidic
ii) basic
iii) neutral
Answer:
iii) neutral

Question 11.
When acids are dissolved in water, they release-
i) oxygen ions
ii) hydrogen ions
iii) nitrogen ions
Answer:
ii) hydrogen ions.

Question 12.
The ion which is present in common salt is-
i) Sodium
ii) Potassium
ii) Berium
Answer:
i) Sodium

Question 13.
Iodine deficiency cause-
i) high blood pressure
ii) low blood pressure
iii) goitre
iv) heart disease
Answer:
iii) goitre

Question 14.
A polymer called polythene is prepared by joining molecules of-
i) Methane
ii) Chlorine
iii) Ethylene (C₂ H₄)
Answer:
iii) Ethylene (C₂ H₄).

Question 15.
The acid present in tamarind-
i) malic acid
ii) lactic acid
iii) acetic acid
iv) tartaric acid
Answer:
iv) tartaric acid

Question 16.
In general taste of alkali is-
i) acidic
ii) bitter
iii) basic
iv) tasteless
Answer:
ii) bitter

Question 17.
A crystaline subject-
i) chalk
ii) lime
iii) sand
iv) sugar
Answer:
iv) sugar

Question 18.
If the pressure of blood increases what may happen in our body-
i) veins can rupture
ii) heart valves may be damaged
iii) blood clots may be formed in the brain
iv) all are true
Answer:
iv) all are true

Fill in the blanks : (1 mark for each question)

1. Most of the things of the earth are made from a reserve of about ________ elements.
Answer:
92.

2. Human body is mainiy formed of the combined mass of __________ elements.
Answer:
four.

3. We get _______ from inorganic compounds.
Answer:
minerals.

4. Using the energy of _____, plants produce glucose.
Answer:
Sunlight.

5. – is an important constituent of the body of organisms.
Answer:
Water.

6. Water constitutes about _____ of the total mass of human body.
Ans:
60 %.

7. An increased quantity of _____ correlates with a decreased _____ content.
Answer:
fat, water.

8. Next to oxygen, ______ is the most important requirement for our survival.
Answer:
water.

9. The major constituent of bone is a phosphate of ______.
Answer:
calcium.

10. Without ferrous ion (Fe²⁺) ________ of blood’s red blood cell cannot function.
Answer:
haemoglobin.

11. Energy required for germination of the seed comes from ______ stored in it.
Answer:
carbohydrates.

12. The protein called haemoglobin transports _______ to different parts of our body.
Answer:
oxygen

13. Bases soluble in water are known as _______
Answer:
alkalis

14. All _______ are bases but all bases are not alkalis.
Answer:
alkalis

15. Lemon juice causes stain on _______ floor.
Answer:
cement

16. The concentrated alkali solution is extremely harmful for skin and _______.
Answer:
eyes

17. _______ is mixed with pond water to decrease its ______ during culture of fish in pond.
Answer:
Lime, acidity.

18. Our body also contains acid in the ______.
Answer:
stomach.

19. ______ of Calcium in our body is in our bones.
Answer:
99 %.

20. _______ is necessary for deposition of Calcium in the bones.
Answer:
Vitamin D.

21. One important constituent of our blood is _______.
Answer:
White Blood Corpuscles (WBC).

22. To meet the demand of salt in reserve forests there are ______ for animals.
Answer:
salt licks.

23. ______ helps in maturation of brain, so it is essential for children.
Answer:
lodine.

24. Generally iodine deficiency problems are more in _______ regions than in plains.
Answer:
hilly.

25. The fibres in the plant body are made of different types of _______ polymers.
Answer:
carbohydrate.

26. The muscles, tendons, ligaments etc of animal bodies are made up of _______, which also are polymers.
Answer:
Proteins.

27. _______ is the sodium or potassium salt of some organic acids which are prepared from the reaction of coustic soda or caustic potash with _______ or oils.
Answer:
Soap, fat.

28. The ______ used for writing or printing is mixture of pigments.
Answer:
ink.

29. _______ is a mixture of oxides and Silicate compounds of many metals like Calcium, Aluminium, Iron etc.
Answer:
Cement.

30. Some of the widely consumed soft drinks in our country are found to contain ______ in alarming quantities.
Answer:
pesticides

State whether True or False : (1 mark for each question)

1. Carbonic acid is present in vinigar.
Answer:
false

2. Apple contains malic acid.
Answer:
true

3. Lactic acid is present in curd.
Answer:
true

4. Our body contais acid in the stomach.
Answer:
true

5. Alkali turns moict red litmus white.
Answer:
false

6. The taste of blood is sour.
Answer:
false

7. Water does not change the colour of litmus paper.
Answer:
true

8. If our kidneys get affected due to some reason, then urea, uric acid and creatinine levels in the blood decrease.
Answer:
false

9. Common salt is a white, crystalline mixture.
Answer:
true

10. Some salt enters our body through the water we drink.
Answer:
true

11. Pure sodium chloride absorbs water from air.
Answer:
false

12. The main constituent of human blood is water.
Answer:
true

13. Milk, curd, bones of small fishes sre the main sources of iron.
Answer:
false

14. Cactas, Acacia, Palm grow in hot and dry areas.
Answer:
true

15. Iodine helps in maturation of brain.
Answer:
true

16. Many small molecules join together to form a molecule of a polymer.
Answer:
true

Match the column A with column B.

Column A	Column B
a) PET is used for	i) are present in tomato
b) Many countries has banned	ii) grow in mangrove forest
c) The substances decomposed through	iii) preparing bottle and food boxes
d) Malic, oxalic and sitric acids	iv) high temperature
c) Carbonic acid is present	v) haemoglobin cannot be formed
f) Animals that hunt at night	vi) DDT as pesticide
g) Cactus can tolerate	vii) natural process are known biodegradables
h) Without ferrous ion	viii) red litmus blue
i) Sundari trees	ix) can see in the dark
j) Alkali turns	x) in sodawater

Answer:
a) PET is used for preparing bottle and food boxes.
b) Many countries has banned DDT as pesticide.
c) The substances decomposed through natural process are known biodegradables.
d) Malic, oxalic and citric acids are present in tomato.
e) Carbonic acid is present in sodawater.
f) Animals that hunt at night can see in the dark.
g) Cactus can tolerate high temperature.
h) Without ferrous ion haemoglobin cannot be formed.
i) Sundari trees grow in mangrove forest.
j) Alkali turns red litmus blue.

Very Short Questions & Answers : (1 mark for each question)

Question 1.
What are the main constituents of common salt?
Answer:
Sodium Chloride, Magnesium Chloride, Calcium Sulphate and Potassium Bromide.

Question 2.
What is the symbol of Sodium Chloride?
Answer:
NaCl arrow Sodium ion (Na⁺) + Chloride ion (Cl-).

Question 3.
What are the two functions of Calcium?
Answer:
a) Helps in formation of bones and teeth. b) Controls the function of heart muscle.

Question 4.
What are four elements prevalent in human, bacterial, fungal, plant and animal bodies?
Answer:
Carbon (C). Hydrogen (H), Oxygen (O) and Nitrogen (N).

Question 5.
How plant produce glucose?
Answer:
Utilising carbon dioxide from air, taking up water and some minerals from soil and using the energy of sunlight, plants produce glucose.

Question 6.
How the harmful compounds of our body are excreted?
Answer:
It occurs through sweat and urine most of which is water.

Question 7.
What are the two different components of paints?
Answer:
i) Solvent part (generally colourless or light-coloured liquids)
ii) pigment part (particles of coloured compounds)

Question 8.
What is the reason for wide use of cement?
Answer:
This is because cement is easily available, can adapt itself with weather and structures made of cement have a high longevity.

Question 9.
What will happen of you prepare ball of cement, sand and water and keep it overnight?
Answer:
The entire ball will get hardened.

Question 10.
Write the name of theree non-metallic element.
Answer:
i) Oxygen ii) Carbon iii) Hydrogen

Question 11.
What link a fuel to our body?
Answer:
Regarding production of energy in the body of an organism, carbohydrates may be likened to a fuel.

Question 12.
What is protein?
Answer:
Protein is a class of compound without which life cannot be imagined.

Question 13.
Where protein is found in our body?
Answer:
Proteins are found in skin, muscle, nail, hair and blood.

Question 14.
What speed up numerous chemical reactions that occur in our body?
Answer:
Various enzymes.

Question 15.
On what the external appearance of the progeny of an organism depends. is
Answer:
The external appearence of the progeny of an organism depends on their nuclic acid.

Question 16.
What partly determines the behavioural pattern of an animal?
Answer:
The behavioural pattern of an animal is determined partly by its genetic make up.

Question 17.
Name the four metals that are essential for our survival.
Answer:
These metals are Sodium, Potassium, Catcium and Iron.

Question 18.
When you eat fried fish, you ingest very small pieces of bone along with the fish, what it contains?
Answer:
It contains a phosphate compound of Calcium.

Question 19.
What is there in the Calcium tablets prescribed by doctor?
Answer:
It contain Calcium Carbonate (CaCO₃), along with some organic substances.

Question 20.
What is there in anima! liver?
Answer:
It contains specific organic compounds of iron.

Question 21.
What is required for the proper functioning of nervous system?
Answer:
It requires the right balance of Sodium and Potassium ions (Na⁺.and .K⁺)in our body.

Question 22.
Name four organic compounds which play a vital role when life first came into being?
Answer:
i) (‘arbohydratc. ii) Protein, iii) lipid, iv) nucleic acid.

Question 23.
With what tie iatu exiernal shell of snails, conches and the like is made of?
Answer:
Calcium Carbonate.

Question 24.
How many elements are present in living organisms in form of various compounds?
Answer:
16 elements.

Question 25.
How is lipid important?
Answer:
Breakdown of lipids in a cell given energy. Moreover the layer of lipid below the skin of an animal protects it from cold.

Question 26.
Name some substances other than fruit which tastes sour?
Answer:
Sour milk, vinegar, curd.

Question 27.
What is acid?
Answer:
An acid is a substance which produces hydrogen ions (H^–)when dissolved in water.

Question 28.
From where the word acid come from?
Answer:
The word acid came from the Latin word Acidus, which means ‘sour’.

Question 29.
Name an acid which produced in our stomach, how is it useful?
Answer:
Hydrochlcric acid, it helps in the digestion process.

Question 30.
What we take to reduce acidity in stomach?
Answer:
An antacid, which is a base, is taken.

Question 31.
What is neutralisation reaction?
Answer:
The reaction of an acid with a base to form salt and water is called neutralisation reaction.

Question 32.
Which acid is present in ant bite?
Answer:
Formic acid ( HCOOH).

Question 33.
What is base?
Answer:
A base is a ompound that produces hydroxyl ions when dissolved in water.

Question 34.
What is alkali?
Answer:
A base that is soluble in water is called an alkali.

Question 35.
Write the dissociation reaction of HCl in aqueous solution?
Answer:
HCl + H₂O → H₃ ^– + Cl

Question 36.
How can you write the dissociation of slaked lime in lime water?
Answer:
Ca(OH)₂ arrow Ca⁺² + 2 OH^–

Question 37.
What is p H scale?
Answer:
The strength of acidity or basicity of a solution is measured by pH scale.

Question 38.
How much of our daily food should be acidic and basic?
Answer:
Our daily food should be 20% acidic and 80% basic.

Question 39.
Name the foods which are basic in nature.
Answer:
Foods coming from plant origin are mainly basic in nature e.g. fruits, nuts, legumes and vegetables.

Question 40.
Name the foods which are acidic in nature.
Answer:
Foods coming from animal origin like fish, meat,egg are acidic.

Question 41.
How many types of salt do we use now a days as food?
Answer:
They are mainly of three types –
(i) Sea salt
(ii) Rock salt
(iii) Table satt.

Question 42.
What is the medium of communication in our body?
Answer:
It is our nervous system, which is continuous from our nails of feet to head.

Question 43.
What assists the nerve in the activity of communication?
Answer:
To exchange impulse between brain, spine and different parts of the body the main helper of nerve is the sodium ion (Na⁺)present in the colımon salt.

Question 44.
What will happen if the level of salt in our body suddenly decreases due to some reason?
Answer:
For this sparm will occur in different parts of the body, talking will become inconsistent.

Question 45.
Where from the word ‘polymer’ is derived?
Answer:
The word ‘polymer’ is derived from two Greek words ‘poly’ and ‘meros’. ‘Poly’ means many and ‘meros’ means parts.

Question 46.
Name some fertilisers.
Answer:
Urea, Ammonium Sulphate, Ammonium Phosphate.

Question 47.
Name some pesticides.
Answer:
Methyl parathion, Aldrin, Carboryl.

Question 48.
What are the adverse effects of Lead and Mercury?
Answer:
Lead causes – loss of appetite. nausea, headache.
Mercury causes – Loss of sense in facial and tongue muscles, kidney damage.

Question 49.
What has been found in some of the widely consumed soft drinks in our country?
Answer:
Some of the widely consumed soft drinks in our country contains pesticides in alarming quantities.

Question 50.
What herbal medicine was used earlier for small cuts or bruises?
Answer:
Extract of marigold plant or grass .

Question 51.
In early days what was used for dying of clothes?
Answer:
Indigo.

Question 52.
Whose body contains more water male or female?
Answer:
male

Question 53.
Whose body contains more water child or adult?
Answer:
child.

Question 54.
Whose body contains more water a thin person or a fat man?
Answer:
thin person.

Question 55.
Whirh acid is present in vinigar?
Answer:
Acetic acid.

Question 56.
Which acid is present in orange?
Answer:
Citric acid and ascorbic acid.

Question 57.
Which acid is present in lemon?
Answer:
Citric acid and ascorbic acid.

Question 58.
Where the maximum amount of Calcium lies in our body?
Answer:
99% of Calcium in our body is in our bones.

Question 59.
What is organic Sea-salt?
Answer:
A special type of salt is produced from pollution-free ocean source, known as organic Sea-salt.

Question 60.
What is the effect of reduced activity of thyroid glands on females?
Answer:
The reduced activity of thyroid gland: may lead to infertility in females.

Question 61.
Which acid is present in apple?
Answer:
Malic acid.

Question 62.
Which acid is present in tomato?
Answer:
Malic acid, oxalic acid and citric acid.

Question 63.
Which acid is present in sodawater?
Answer:
Carbonic acid.

Question 64.
Which acid is present in tamarind?
Answer:
Tartaric acid.

Question 65.
Which acid is present in curd?
Answer:
Lactic acid.

Question 66.
What is the role of vitamin D in our body?
Answer:
Regulates the absorption of calcium and phosphorous in the intestine, mineral deposition in bones and teeth.

Question 67.
What are the function of different enzymes present in our body?
Answer:
To initiate and speed up the bio-chemical reaction.

Question 68.
How does glucose produce energy in our body?
Answer:
Glucose is broken down by enzymes during digestion to produce energy in our body.

Short Questions & Answers : (2 marks for each question)

Question 1.
Why is iodized salt necessary for our body?
Answer:
lodine helps in maturation of brain, so it is essential for children. Moreover, deficieicy of iodine may lead to physical and mental depression and Goitre.

Question 2.
What is pH scale? How is it important?
Answer:
The strength of acidity or basicity of a solution is measured by pH scale.
At 25° C the pH of a neutral solution (e.g. water) is 7 . The solution having a pH less than 7 (upto zero) is acidic in nature. The solution having a pH greater than 7 (upto 14) is basic or alkaline.

Question 3.
What is thyroid gland?
Answer:
If you touch the sides of your vocal chord with fingers, you will find the presence of two small glands. These are thyroid glands.

Question 4.
What is Goitre?
Answer:
In case of iodine deficiency the thyroid glands get enlarged in trying to function normally. The throat get abnormallly swollen and this is known as Goitre.

Question 5.
What is soap?
Answer:
Soap is the Sodium or Potassium salt of some organic acids which are prepared from the reactions of Caustic Soda or Caustic Potash with fat or oils.
Fats or Oils + Caustic alkali → Soap + glycerine.

Question 6.
What is polymer?
Answer:
A polymer is a chemical compound with large molecules made of many smaller molecules of the same kind. Some polymers exist naturaly and other are produced in laboratories and factories.

Question 7.
What harm nylon net are causing in the environment?
Answer:
Offsprings of Hilsa fishes and baby turtles are dying in the nylon net with smaller gaps. Thus the biodiversities are being destroyed.

Question 8.
Why centent and sand-based construction need watering?
Answer:
In prisence of water the Calcium hyroxide water also adds to different silicate compounds of cement. As heat is liberated in these reactions, cement may be cracked. So concrete casting needs watering.

Long Questions & Answers : (3 marks for each question)

Question 1.
How is water helpful in human body?
Answer:
Water is the most important requirement for our survival. After several days without water lruman beings may die. Water helps us to transport the simple compounds generated by digestion of carbohydrates. lipids and proteins to different parts of our body. Harmful compounds formed in our body are excreted through urine, that is basically a watery fluid.

Question 2.
What are the two factors on which the acid-base balance of human body depends? Why it is necessary to maintain a fixed acid-base balance in human body?
Answer:
The acid-base balance of human body depends mainly on two factors –
a) Amount of carbon dioxide released by respirartion.
b) Different changes by chemical reactions occuring in our body.
It is necessary to maintain a fixed acid-base balance in human body because different parts of the body enamel of teeth. bone joint are affected and aging process may become faster.

Question 3.
What is the sources of Calcium that is essential for body?
Answer:
Food from animal origin e.g. – milk, curd, bones of small fishes etc.

Question 4.
Which organization established factories of iodized salt in different parts of the country? In which year the production of iodized salt became sufficient?
Answer:
Factories for the production of iodized salt in different parts of the country were established under the collaboration of WHO and UNICEF. In 1983 the production of iodized salt became sufficient for Indian population.

Question 5.
In most cases, mango or other fruit or vegetable slices are coated with common salt and dried in the sun, why?
Answer:
This is done due to two reasons.
(i) So that mango slices lose most of the water.
(ii) So that those pickles are protected from aerial germs for a long time.

Question 6.
Why salt is used to preserve food since antiquity?
Answer:
The germs when come in contact with sait, they lose cell fluid by osmosis. As a result the germs are killed, this helps topreserve food.

Question 7.
Give example of some natural polymer.
Answer:
The fibres in the plant body are madc up of different types of carbohydrate polymers. On the other hand, the muscles, tendons, ligaments etc of animal bodies are made up of proteins. which also are polymers.

Question 8.
How many types of plastics are there?
Answer:
Plastics can be classified into two types –
i) Thermo plastics : This type of plastic is soft and can be melted and remoulded repeatedly. Examples include polyethylene, polystarene and PVC.
ii) Thermosetting plastic: This type of plastic is hard and they can be melted and moulded only once. They cannot be melted and remoulded again. Examples include bakelite, melamine, teflon.

Question 9.
What are detergents?
Answer:
Detergents are water soluble compund of organic acids prepared by the reaction of hydrocarbon compounds from petroleum or other sources, and concentrated Sulphuric acid.The commercially available detergents are mixture of different compounds.

Question 10.
What are the harmful effects of DDT and other pesticides?
Answer:
It has been found that a breakdown product of DDT makes the eggshell of birds and tortoises thin and brittle. The egg breaks into pieces as the birds sit on them during into incubation. The pesticides have adverse effects on honeybees. silkworm and different types of birds. When consume with food, the pesticide also create different types of discases in human body.

Question 11.
What does glass consists of? What mixed compound is used to prepare yellow, blue and greeen coloured glass?
Answer:
Glass is a mixture that is prepared mainly from limestone, soda ash and sand.
Metallic oxides used to prepare coloured glasses are – Iron oxide is used for yellow glass, Cobalt oxide used for blue glass and Chromium oxide is used for green glass.

Question 12.
Define biodegradable and non-biodegradable wastes.
Answer:
The subtances that degrade or decompose through natural processes are known as biodegradable. Those that are not degraded like that are known as non-biodegradable.

The two types of wastes are – Entirely different in their structures and properties like water retaining ability etc. Animal bodies are completely biodegradable but manmade synthetic products are mostly non-biodegradable.

Question 13.
What are the general properties of common salt?
Answer:

1. The colour of edible (common) salt is generally white.
2. In-normal condition it is a hard substanee.
3. Common salt is soluble in water.
4. It is a crystalline solid.

Detailed explanations in West Bengal Board Class 7 Science Book Solutions Chapter 5 Human Food offer valuable context and analysis.

WBBSE Class 7 Science Chapter 5 Question Answer – Human Food

(Page no. 145)

Let’s make a list of our daily work from the following pictures.
Answer:

(Page no. 147)

So, what kinds of food (plant/animal) do we eat? Which food component is less or excess in these food items? Discuss with your teachers and fill up the following chart from the discussions later on.

(Page no. 148)

Let’s make a chart showing food components present in different common foods. Take help from your teacher to fill up the following chart.

Food Source	Main Food elements
1. Rice, roti, milk, fruit, potato, sweet potato, honey, sugar, jaggery	Carbohydrate
2. Fish, meat, egg, milk, pulses, cheese, soyabean	Protein
3. Butter, ghee, coconut, groundnut, oil, animal fat. milk, fish	Lipid
4. Drinking water, fruits, vegetables, tea, milk, cooked food	Water
5. Tomato, amla, whole wheat grain, carrot, green vegetables, fruits	Vitamin
6. milk, salt, rice, molasseo, meat, leafy vegetables, milk, fish, pulses	Mineral
7. Mango, apple, oat, papaya, leafy vegetables, whole grains, pulses	Food fibre
8. Tea, ripe mango, ripe papaya, beet, pomegranate, watermelon	Phytochemical.

Page no. 150

Apart from the food items mentioned on the previous page some more are mentioned in the table below. Ask your teacher to know whether these contain carbohydrates or not.

Food	Present/Absent
1. Pumpkin	Present: 7gr./100gr.
2. Raisin             .	Present : 79gr./100gr.
3. Custard-apple	Present: 24gr./100gr.
4. Berry	Present: 14gr./100gr.
5- Egg	Present: 1.1 gr./100gr.
6. Cumin	Present: 44gr./100gr.
7. Curd	Present: 3.4gr./100gr.
8. Cake	Present: 59gr./100gr.
9. Ghee	Absent: 0gr./100gr.
10. Flattened rice	Present: 40gr./100gr.

(Page no. 152)

Apart from the food items mentioned above, some more mentioned in the table below. Ask your teacher to know whether these contain protein or not.

Food	Present/Absent
1. Rice/wheat	Present: 2.7gr./100gr, 12.61 gr./ 100gr.
2. Ghee	Absent: 0.3 8gr./100gr.
3. Groundnut	Present: 26gr./100gr.
4. Sesame	Present: 18gr./100gr.
5. Banana	Present: 1.1 gr./100gr.
6. Mushroom	Present: 3.1 gr./100gr.
7. Suji	Present: 13gr./100gr.
8. Ant eggs	Present: 8.2gr./100gr.

(Page no. 153)

Try to find out if lipid is present in the food mentioned in the table below.

Food / Drink	Present/Absent
1. Fruits and vegetables	Absent
2. Cereals	Absent
3. Tonnedmilk	Absent
4. Popcorn	Absent
5. Potato	Absent
6. Sugarcane juice	Absent
7. Lemon	Absent
8. Wheat, mazie, rice	Absent
9. Mushroom	Present
10. Chicken	Present
11. Dates	Absent

(Page no. 161)

Put the name of food components and their sources in the following table.

Food component	Food
1. Sugar	Rice, wheat, Bazra, potato, beat, carrot, sugar.
2. Protein	Fish, meat. egg. milk, pulse, soyabean, peas.
3. Lipid	Nut. coconut, ghee, butter, oil, fish, fat of meat.
4. Vitamin	Capsicum, tomato, green vegetables, gram, milk
5. Minerals	Green vegetables, food grain, soyabean, fish, meat, egg.
6. Water	All types of rinking water, fruit juice, coconut water
7. Fibre	Cereal, apple, oat, papaya, broccoli, figs, berries.
8. Plant chemical	Tea, cabbage, carrot, tomato, ripe mango

(Page no. 161)

Some physiological problems are mentioned. Which foods are required to prevent these health problems?

Problems	Which food should you have	Which food component will you get
Swollen gums with bleeding	Sour fruits, amla, lemon, guava	Vitamin C
Anaemic condition	Egg. milk, banana, guava	Vitamin B-complex
Weak and curved bones	Egg, milk, butter, cod liver oil	Vitamin-D
Constipation	Vegetables, cabbage, guava	Fibre
Short sight at night	Vegetables, milk, carrot, tomato	Vitamin-A
Ulcer in mouty and tongue	Egg, milk, spinach.	Vitamin B-complex
Wrinkled skin	Carrot, letus. egg, milk, raddish	Vitamin-A
Sudden rise in blood pressure	Small fish, vegetables, fruits	Sodium

(Page no. 162)

There are a few names of food. Try to find out which food components can you get from them. Take help from your teacher, if necessary.

• Ripe mango : Food fibre, sugar, vitamin
• Milk: Protein, vitamin, lipid, minerals
• Nuts : Lipid, vitamin, carbohidrate
• Egg : Protein, vitamin, lipid, minerals
• Guava : Vitamin, minerals, sugar
• Gurd : Vitamin, minerals, sugar
• Tomato : Vitamin, plant chemicals
• Rice : Carbohidrate, vitamin
• Spinach : Vitamin, minerals, foodfibre
• Amla : Vitamin, minerals

(Page no. 166)

Following symptoms develop due to defficiency of different food components. Write down the names of food items that can prevent these diseases.

Symptoms	Defficiencyof food component	Somponents are found in
Bent limbs	Vitamin D	Milk, egg, butter, fish
White spot in iris	Vitamin A	Carrot, egg, milk, curd, letus
Can’t read blackboard	Vitamin A	Carrot, egg, milk, curd, letus
Ulcer on tongue, nouth	Vitamin B Complex	Vegetable, cabbage, milk, green chilli
Swollen face	Protein	Milk, fish, meat, panir, soyabean
Broken nails	Calcium	Milk, amla, lemon, guava
Rough skin	Vitamin A	Carrot, egg, milk, curd, letus

(Page no. 166)

Weight and height of some children and adults are mentioned below. Calculate BMI from it.

Weight (kg)	Height (m)	BMI (weight/height2)	Obese yes/no	Synptoms
62	1.57	25.15	no	normal
66	1.50	29.33	yes	high blood pressure, asthma
72	1.59	28.47	yes	(respiratory problem, diabetes
64	1.62	24.38	no	normal
75	1.60	29.29	yes	high blood pressure, asthma
71	1.58	28.44	yes	knee pain, asthma
72	1.67	25.81	no	normal

Class 7 Science Chapter 5 Question Answer West Bengal Board – Human Food

Multiple Choice Questions & Answers : (1 mark for each question)

Question 1.
Which is known as instant source of energy ……………………….
i) starch
ii) vitamins
iii) minerals
iv) glucose
Answer:
iv) glucose

Question 2.
Dificiency of iron in our diet casues ……………………….
i) scurvy
ii) anaemia
iii) goitre
iv) blindness
Answer:
ii) anaemia

Question 3.
Plants manufacture food in the form of ……………………….
i) starch
ii) fructose
iii) glucose
Answer:
iii) gluuose

Question 4.
What helps in removing wastes from the body ……………………….
i) water
ii) protein
iii) glucose
iv) phytochemical
Answer:
i) water

Question 5.
Starch is a complex ……………………….
i) mineral
ii) lipid
iii) glucose
iv) carbohydrate
Answer:
iv) carbohydrate

Question 6.
Daily requirement of carbohydrate by an adult is ……………………….
i) 500 gram
ii) 300 gram
iii) 600 gram
iv) 100 gram
Answer:
i) 500 gram

Question 7.
Marasmus is due to the deficiency of ……………………….
i) vitamin C
ii) carbohydrate
iii) fat
iv) protein
Answer:
iv) protein

Question 8.
To get sufficient carbohydrate one should take ……………………….
i) meat
ii) rice
iii) carrot
iv) ground nut
Answer:
ii) rice

Question 9.
What one of the following is the best source of vitamin-A?
i) egg
ii) honey
iii) carrot
iv) pea nut
Answer:
iii) carrot

Question 10.
Fat soluble vitamins are ……………………….
i) A D E and K
ii) B C and D
iii) D B and E
iv) A B and C
Answer:
i) A D E and K.

Question 11.
Vitamin essential for blood clotting is ……………………….
i) A
ii) E
iii) C
iv) K .
Answer:
iv) K

Question 12.
Which one is body-building material?
i) mineral
ii) Protein
ii) fat
iv) sugar
Answer:
ii) Protein

Question 13.
Scurvy disease causes in deficiency of vitamin ……………………….
i) C
ii) B
iii) K
iv) A
Answer:
i) C

Question 14.
Artificial chemical Ajinamoto is used to make ……………………….
i) chocolate
ii) popcorn
iii) momo
iv) tea
Answer:
iii) momo

Question 15.
Trans-fat is present in ……………………….
i) pastry
ii) potato chips
iii) cotton
iv) coffee
Answer:
ii) potato chips

Fill in the blanks : (1 mark for each question)

1. ………….. provides us energy for all life activites.
Answer:
Food

2. Food keeps us healthy and enables us to fight against …………..
Answer:
diseases.

3. In the process of digestion starch a ………….. is broken down into the smallest unit (Glucose).
Answer:
complex carbohydrate.

4. Energy is produced in the cells of the healthy body by break down of …………..
Answer:
glucose.

5. ………….. is caused due to the lack of food fibre in our diet.
Answer:
Constipation

6. The protein that is present in hair and nail is ……………
Answer:
keratin.

7. The protein present in blood is …………..
Answer:
Haemoglobin.

8. ………….. has important role in providing immunity.
Answer:
Protein.

9. ………….. help in coagulation of blood oozing out continuously from any wounded region.
Answer:
Plasma proteins.

10. ………….. reduces heat emission from human body.
Answer:
Lipid.

11. Vitamins A D E and K are …………..
Answer:
Fat-soluble.

12. B-complex and C vitamins are ………….. vitamins.
Answer:
water-soluble.

13. Vitamin ………….. helps to maintain the structure of eye skin bones and teeth.
Answer:
A

14. Vitamin …………… maintains the structure of bones and joints.
Answer:
D

15. Deficeincy of iron causes ……………
Answer:
Anaemia.

16. …………… controls mental abilities and mental growth.
Answer:
Iodine.

17. Deficiency of …………… causes increase in blood sugar level.
Answer:
zinc.

18. The …………… part of food comes out of the body as stool.
Answer:
undigested.

19. Excessive water loss from the body causes ……………
Answer:
dehydration.

20. Deficiency of proteins lipids and carbohydrates in the diet casues …………..
Answer:
Marasmus.

21. Protein malnutrition results in a disease called …………..
Answer:
Kwashiorkar.

22. The kitchen of plant is …………..
Answer:
leaf.

State whether True or False : (1 mark for each question)

1. High blood pressure is related with iodine.
Answer:
false

2. Iodine controls mental abilities and mental growth.
Answer:
true

3. Sodium maintains water level in body.
Answer:
true

4. Source of iodine is vegetables.
Answer:
false

5. Iron helps in transporting oxygen in tissues.
Answer:
true

6. Plant source of lipid is fish oil..
Answer:
false

7. Keratin is present in hair and nail.
Answer:
true

8. Collagen is present in tendon and ligament.
Answer:
true

9. Protein is the main food component of ground nut butter coconut.
Answer:
false

10. Deficiency of vitamin causes ulcer at the corner of lips.
Answer:
true

11. Due tr deficiency of iodine symptom of high blood pressure is seen.
Answer:
false

12. For deficiency of vitamin A.one can not read blackboard from the last bench.
Answer:
true

13. Processed foods are richest in nutritional value.
Answer:
false

14. The foods obtained directly from mature are called natural foods.
Answer:
true

15. About 75% of earth’s surface is covered by water.
Answer:
true

Match the column A with column B

Column A	Column B
a) Aquatic plants absorb water	i) 60% water by mass
b) High fever occurs in	ii) is the cause of blindness
c) Human body has	iii) which can not be digested
d) Natural foods are richest	iv) from plants or animals or from water
e) Deficiency of Vitamin A	v) with their whole body
f) We get phytochemicals	vi) Malaria or Pneumonia
g) Stool has fibres	vii)root and other parts
h) Plant absorb water through	viii) in nutritional value
i) Deficiency of iodine	ix) from tomato                        ‘
j) Animals get minerals              .	x) causes goitre

Answer:
a) Aquatic plants absorb water with their whole body.
b) High fever occurs in Malaria or Pneumonia.
c) Human body has 60% water by mass.
d) Natural foods are richest in nutritional value.
e) Deficiency of Vitamin A is the cause of blindness.
f) We get phytochemicals from tomato.
g) Stool has fibres which can not be digested.
h) Plant absorb water through root and other parts.
i) Deficiency of iodine causes goitre.
j) Animals get minerals from plants or animals or from water.

Very Short Questions & Answers : (1 mark for each question)

Question 1.
What is needed to do daily work?
Answer:
Energy is needed to do daily work.

Question 2.
What is the source of energy in our body?
Answer:
Healthy and balanced diet is the source of energy in our body.

Question 3.
Which is ‘energy giving food’?
Answer:
Carbohydrates are energy giving food.

Question 4.
Which is ‘body building food’?
Answer:
Protein is body building food’.

Question 5.
What are protective foods?
Answer:
Vitamins and minerals are protective foods.

Question 6.
Name some plant sources which supply carbohydrate.
Answer:
Rice, wheat, potato, beet, pulses etc. are some sources which supply carbohydrate

Question 7.
Name some animal sources which supply carbohydrate?
Answer:
Honey, milk, meat, liver etc. are some animal sources which supply carbohydrate.

Question 8.
Which disease occurs due to unavailability of glucose in cells?
Answer:
Diabetes Mellitus occurs due to unavailability of glucose in cells.

Question 9.
What are the functions of muscles of our hands?
Answer:
Muscles of hand help to lift, push, pull things.

Question 10.
What are the functions of muscles of our legs?
Answer:
Muscles of leg help in walking, running, climbing jumping etc.

Question 11.
What is the function of Heart?
Answer:
Circulation of blood in our body.

Question 12.
What is the function of Lungs?
Answer:
It helps in respiration.

Question 13.
What is the function of Intestine?
Answer:
Digestion of food is the function of Intestine.

Question 14.
Name the protein present in hair and nail?
Answer:
Keratin is present in hair and nail.

Question 15.
Name the proteins present in muscle?
Answer:
Actin, Myosin.

Question 16.
Name the protein present in Red Blood Corpuscle?
Answer:
Haemoglobin.

Question 17.
Which proteins are in blood plasma?
Answer:
Globulin. Fibrinogen.

Question 18.
Collagen protein is present in which body parts?
Answer:
Bone. Tendon, Ligament.

Question 19.
Nans some plant sources which supply protein.
Answer:
Pea, kindney bean, seeds of jackfruit, millet, corn, garlic, clove, turmeric etc.

Question 20.
Name some animal sources which supply protein.
Answer:
Ghana, Paneer, Crab, milk, meat, fish, eggs etc.

Question 21.
Name some plant sources of lipid.
Answer:
Coconut, jackfruit, vegetable cooking oil, whole wheat grain etc.

Question 22.
Name some animal sources of lipid.
Answer:
Fish oil, milk, curd, meat, ghee, butter, egg yolk, meat, cheese etc.

Question 23.
Beri-Beri causes due to lack of which vitamin?
Answer:
Vitamin B.

Question 24.
Which vitamin deficiency disease was common in Europe nearly 500 years ago?
Answer:
Scurvy.

Question 25.
Which vitamin deficiency casues scurvy?
Answer:
Vitamin C.

Question 26.
Which vitamin helps in blood clotting?
Answer:
Vitamin K.

Question 27.
Which plant sources supply vitamins?
Answer:
Ripe mango, pumpkin, fig, tomato, spinach, cabbage and other green leafy vegetables.

Question 28.
Which animal sources supply vitamins?
Answer:
Meat, ghee, eggs, milk, fish, etc.

Question 29.
Name some sources of vitamin B complex.
Answer:
Cereals, cabbage, leaves of raddish, small fishes, chili, milk etc,

Question 30.
Name some essential minerals which our body requires.
Answer:
Iron, Calcium, Magnesium, Sodium, Iodine, Zinc etc.

Question 31.
Which parts of the plant produce food?
Answer:
Food is produced in leaves and other green parts.

Question 32.
What is the right amount of water that one drink daily?
Answer:
A healthy adult shout eat 50 ml/kg body weight to meet the daily requirement.

Short Questions & Answers : (2 marks for each question)

Question 1.
What is food? Why is food essential?
Answer:
The source of our energy and disease resistant component is food.
All living beings need energy to remain alive and active. The food we eat provides us with energy as well as those things that our body needs to stay alive and healthy.

Question 2.
What are the main components of food?
Answer:
The main components of food are –

• Carbohydrate
• Protein
• Lipid
• Vitamin
• Water
• Mineral
• Food fibre
• Phytochemical.

Question 3.
Define macronutrients and micronutrients.
Answer:
Carbohydrates, fats and proteins make up to bulk of our food. They are called macronutrients.
Vitamins and minerals though crucial for health, are needed in small quantities. They are called micronutrients.

Question 4.
Why Food fibres and water are also important components of our food?
Answer:
Food fibres from the roughage part of our food. They help in the movement of bowel in the intestine. Water helps our body to absorb nutrients from the food. It also helps in removing wastes from the body.

Question 5.
Mianly how many types of carbohydrate are there in our food?
Answer:
Carbohydrate which we get from our food to keep us strong is mainly of two types— glucose and starch.

Question 6.
How is energy produced in our body?
Answer:
Energy is produced in the cells of the healthy body by breakdown of glucose. That energy is required for different works.

Question 7.
‘Sometimes intake of milk causes problem’, — What is the reason behind it?
Answer:
Some children or aged persons suffer from different problem after intake of milk or milk products. Indigestion of leactose, a milk carbohydrates, leads to this type of problem.

Question 8.
What leads to obesity? In which body parts lipid is stored in huge amount in an obese person?
Answer:
Eating more of energy-rich food than required by the body causes I ipid deposition in the body and leads to abesity. Lipid containing body parts are neek, upper arm, chest, abdomen and thigh, in an obese person.

Question 9.
How is lipid important? What problem will arise if lipid is stored more than necessary?
Answer:
Lipid acts as sources of energy in the human body and protects the body from external injury. It also reduces heat emission from human body. If more than necessary lipid is stored, the condition can create different problems in heart, blood vessel and liver.

Question 10.
How many types of vitamins are there?
Answer:
Vitamins are of two types—

• Fat-soluble vitamin—A, D, E and K.
• Water-soluble vitamin—B complex and C.

Question 11.
Name some natural pigments which are present in food from plant sources. How are they helpful to us?
Answer: Some coloured pigments present in plant sources are caroteinoids, flavonoids. They stop fast ageing of human body, keeps healthy functioning of heart, strengthen bones. They also check cancer.

Question 12.
What is balanced diet?
Answer:
The diet which contains all the essential nutrients in just the right proportion is called a balanced diet. It varies from person to person depending upon sex. age, group of profession.

Question 13.
What are the symptoms of malnutrition in the child?
Answer:

• Decay of bone in body.
• Muscle is distinct from outside.
• Skin is wrinkled here and there.
• Hands and legs are thin.

Question 14.
Below write the names of different dificiency diseases.
1. Iron dificiency = —
2. Iodine deficiency = —
3. Vitamin D deficiency = —
4. Vitamin B complex deficiency = —
5. Vitamin A dificiency = —
6. Deficiency of protein and energy = —
Answer:
1. Anaemia
2. Goitre, mental retardation, squint
3. Ricket
4. Beriberi
5. Blindness
6. Marusmus, Kwashiorkar.

Question 15.
Why artificial food should not be taken in huge quentity?
Answer:
Artificial food is highly priced by the nutrient level in near by nil. Over consumption of these foods leads to problem of heart, liver, kidney, bones or brain.

Question 16.
What are the symptoms of low blood pressure?
Answer:
Hyponatremia ossures when sodium levels in the blood are too low. Symptoms include lethargy, confusion, and fatigue.

Long Questions & Answers : (3 marks for each question)

Question 1.
Why the diseases Mamasmus and Kwashiorkar occur?
Answer:
The disease caused by malnutrition is called Marusmus. Deficiency of protein and energy in diet lead to this disease. This is predominant in children below one year. Kwashiorkar disease develops in children of 1-4 years old due to deficiency of protein. Children . suffering from Kwashiorkar show stunted growth, large potlike belly, mental retardation swollen face and dark skin.

Question 2.
What can be the reason of obesity? What are the effects of obesity?
Answer:
Obesity occurs due to excessive intake of junk food like pizzas, potato wafers, noodles, icecream and soft drinks which contain excessive lipid. Viewing of TV instead of playing outdoor games, is another cause of obesity. Obese persons are prone to heart disease and high blood pressure (hypertension), ft leads to arthritis, diabetes and anaemia. Obesity also causes discomfort and breathlessness.

Question 3.
When malnutrition occurs?
Answer:
The chance of malnutrition increases if deficiency of energy producing food components are found in diet. Energy producing food components are carbohydrate, protein and lipid. Deficiencv of other food components (vitamin and mineral) also lead to many problems. Worms can be a reason for malnutrition.

Question 4.
Discuss role of water and light in production of food in plants.
Answer:
Plant absorbs water through root and other parts, sends the absorbed water to leaves. Plant absorbs a small amount of light energy from sunlight. Plants begin the process Photosynthesis with the help of light energy and green pigment chlorophyll. Food is produced in leaves and other green parts by water, sunlight and carbon dioxide absorbed from air.

Question 5.
Describe the importance of water in our body.
Answer:
Water is needed for the following functions :

• It maintains our body temperature.
• It is needed in the excretion of wastes.
• It acts as a medium for biochemical reactions in our body.
• It helps in the transportation of nutrients within the body.
• It is an essential part of digestive juices and blood.

Question 6.
What is fibre? How is food fibre helpful?
Answer:
Fibre is a type of Carbohydrate of the nature of cellulose or protein. These may or may not be dissolved in water. The food fibres are formed of cellulose. Since we cannot digest cellulose, human body cannot yield energy from food fibres, it also does not provide us any nutrients.

They simply add bulk to our food and help to get rid of undigested food. Therefore, food fibre help in proper digestion of food as well as in easy and regular movement of bowel. This prevents constipation, colon cancer, obesity high blood pressure and reduces acidity in the stomach.

Question 7.
What will happen if glucose does not enter into cell from blood?
Answer:
Glucose then circulates through blood till it excretes out from the body through kidney. Different organs (heart, kidney, eye, leg) malfunction due to unavailability of glucose in cells. This condition is termed as Diabetes Mellitus. This disease is very common in India. Proper diet and regular exercise can help to prevent this disease.

Question 8.
Why are minerals necessary? Mention some of its function.
Answer:
Minerals are necessary for proper growth of body and to maintain good health, like vitamins, minerals does not supply energy to our body. Some functions are —

• Calcium — maintains muscle contraction, helps in blood coagulation.
• Sodium — maintains water level in body.
• Iron — helps in transport of oxygen, needed for the formation of red blood cells.
• Iodine — controls mental abilities and mental growth.
• Zinc — maintains brain functioning and blood sugar level.
• Calcium, Phosphorus, Magnesium — develop bones and teeth.

Question 9.
Name some minerals necessary for our body. How do plants and animals obtain these minerals?
Answer:
Some minerals necessary for our body are — Iron, Calcium, Magnesium, Sodium, Potassium, Zinc etc.
The minerals are obtained from living organisms as well as non-living compounds.

• Plants collect minerals from soil or ground water under soil.
• Animals get minerals from plant foods, animal foods or water.

Question 10.
What would happen if body looses excessive water? What precautions should be taken then?
Answer:
Excessive water loss from the body causes dehydration. Due to dehydration blood becomes thicker, causing severe pain and cramps. In order to make up the loss of water and minerals from the body, we should drink a solution prepared by adding one teaspoonful of sugar and a pinch of salt to 200 ml of water. This solution is called Oral Rehydration Solution (ORS).

Question 11.
What is starch? How is glucose important to our body?
Answer:
Starch is a complex carbohydrate. In the process of digestion, starch, is broken down into the smallest units (Glucose). This glucose is transported to peripheral regions through blood. Here the absorbed oxygen helps in production of energy from glucose in body. This energy helps in different performances.

Question 12.
Describe the importance of protein in our body. What will happen if there is excess protein in our body?
Answer:
Different kinds of proteins play important roles in producing energy, formation of tissue or parts of body, healing wounds, transport of respiratory gases, contraction of muscles. Protein has important role in providing immunity. Plasma proteins help in coagulation of blood oozing out continuously from any wounded region. Excess protein in body can lead to arthritis, renal stone and other problems.

Question 13.
Which vitamins (A, D, E, K) are needed in the following cases?
Answer:

Problems	Vitamin
1. Short sight at night	A
2. Curved bones and curved vertebral column	D
3. blood doesn’t easily coagulate in wounded areas	K
4. Damage of red blood cells, heart, brain activity hampered	E

Question 14.
Symptoms are given write down the names of water-soluble vitamin necessary.
Answer:

Symptoms	Vitamin
1. Cracked lips	B-complex
2. Nails and lower part of eye becomes pale	B-complex
3. Loosening and falling of tooth	C
4. Nervous disorder	B-complex
5. Loose motion, Demensia	B-complex

 

Detailed explanations in West Bengal Board Class 7 Science Book Solutions Chapter 6 Morphological Diversity and Functions of Living Components of Environment offer valuable context and analysis.

WBBSE Class 7 Science Chapter 6 Question Answer – Morphological Diversity and Functions of Living Components of Environment

(Page no. 182)

1. Write neatly in the table below, the names of plant food that you ate today and yesterday, Then mention in the table which food is obtained from which part of a plant.
Answer:

SI. No.	Names of the food	Which part of the plant
1.	Rice	Seed/fruit
2.	Roti	Seed/fruit
3.	Dal	Seed
4.	Brinjal	Fruit
5.	Spinach	Leaf

2. Give it a thought: are all foods that you get from under the soil really roots from plants? Write in the table below:
Answer:

SI. No.	Names of the food	Root/Stem
1.	Carrot	Root
2.	Beet	Root
3.	Potato	Modified stem
4.	Ginger	Modified stem
5.	Radish	Root

(Page no. 185)

1. Write down the nature of roots of the following plants and complete the chart :
Answer:

SI. No.	Plant Name	Root type
1.	Indian periwinkle	Tap root
2.	Four O’clock plant	Tap root
3.	Paddy	Fibrous root
4.	Mango	Taproot
5.	Cyanodon	Fibrous root
6.	Water hyacinth	Fibrous root

(Page no. 189)

1. Now try to tell that which plant parts of these following plants are used to climb up.

Plants	Organ
1. Gourd	(a) Root from nodes
2. Pea	(b) Tendrils from branches
3. Blu-pea flower	(c) Tendrils from leaf
	(d) Stem.

Answer:
1. b and c, 2 – d, 3 – a

Known objects	Stem	Not stem	Shape
Datashak	✓	X	thin, long
Cabbage	✓	X	round
Drumstick	X	✓	thin
Potato	✓	X	round
Colocasia	V	X	round or big and long

(Page no. 190)

SI. No.	Name	Type	Morphology	Function
1.	Spine of Bael	Modified aerial aerial stem stem modified into spine	long, sharp spine like	Self protection
2.	Offset of water hyacinth	Modified sub­aerial stem floating over water	soft and long like tube	to float on water
3.	Tuber of potato	Modified underground stem	round in shap	to store food
4.	Stem tendril of pumpkin	Modified aerial stem Creeper like	very thin and soft	to climb over support

(Page no. 192)

Specimen Leaf Name	Shape of that expanded portion of leaf
1. Jhanleaf	small and slender
2. Bamboo leaf	long and slender
3. Hibiscus leaf	Broad in the middle gradually becomes slender towards tip
4. Lotus leaf	Flat and round in shape
5. Chhatim leaf	Flat and short

(Page no. 194)

Leaf parts	Function
1. Lamina	(a) Produce food
2. Petiole	(b) Conduction of water and food
3. leaf base	(c) Holds lamina
	(d) Causes gaseous exchange
	(e) Keep branches attached to the stern

Answer:
1. a and d, 2. b and c, 3. e

(Page no. 195)

Leaf name	Work
1. Tendril of pea	(a) Helps in propagation
2. Spine of opentis	(b) Storage of food
3. Leaf of Aloevera	(c) Absorbs nitrogen from insects body
4. Leaf of Bryophyllum	(d) Helps to climb
5. Leaf of pitcher plant	(e) Prevents excess transpiration

Answer:
1 – d,  2 – e, 3 – b, 4 – a, 5 – c

(Page no. 195)

Plants with simple leaf	Plants with compound leaf
1. Mango	1. Tamarind
2. Banyan	2. Gulmohor
3. Jammun	3. Simul

Class 7 Science Chapter 6 Question Answer West Bengal Board – Morphological Diversity and Functions of Living Components of Environment

Fill in the blanks : (1 mark for each question)

1. ………………. protects the soft root tip from friction with soil particle when it enter the soil.
Answer:
Root cap.

2. Rice, Bryophyllum, grasses have ………………. root.
Answer:
adventitious.

3. An angle formed between leaf and stem, is called ……………….
Answer:
axil.

4. The potato which we eat is actually a ………………. where the plant stores its food for
future use.
Answer: modified shoot.

5. The part which attaches stem and leaf is called ……………….
Answer:
leaf base.

6. The flat expanded part of leaf is called ……………….
Answer:
lamina.

7. Animals differ in the sensitivity of their ………………. organs.
Answer:
olfactory.

8. ………………. mosquitoes spread malaria.
Answer:
Anopheles

9. Cell membranes are called ………………. membrane.
Answer:
selectively permeable

10. Concentrated salt solution is ………………. with respect to the RBC.
Answer:
hypertonic.

11. The stem of a sapling develops from the ………………. of an embryo.
Answer:
Plumule.

12. The roots of a sapling develops from the ………………. of an embryo.
Answer:
radicle

13. Mango is called ………………. fruit.
Answer:
simple

14. Custard apple is called ………………. fruit.
Answer:
aggregate

15. Jackfruit is a ………………. fruit.
Answer:
compound

B State whether True or False : (1 mark for each question)

1. Volatile compounds of human sweat can be recognized by Anopheles mosquito.
Answer:
true

2. Diffusion is faster at lower temperature.
Answer:
false

3. Excess use of insecticide reduces beneficial insects like honey bee.
Answer:
true

4. Seeds develop from the ovule after fertilization.
Answer:
true

5. A flower consists of three parts.
Answer:
false

6. Application of insecticide is a problem of pollination
Answer:
true

7. Deforestation of trees like shimul destroy the shelters of pollinating vectors like bats.
Answer:
true

8. Bats appear when fruits arc cut.
Answer:
false

9. Anopheles moscuitoes recognize the volatile compounds responsible for the sweet smell of fruits.
Answer:
false

10. The spreading of molecules is much faster in gas than in a solution.
Answer:
true

11. Tuberculosis bacteria can only reside in lungs of human.
Answer:
false

12. No bacteria can spoil honey easily.
Answer:
true

Match the column A with column B

Column A	Column B
a) In germination of pumpkin seeds b) In germination of mango seed c) Heat helps to keep our life d) Deforestation is a e) Excess use of insecticide f) Mango is a g) Jackfruit is the example of h) The part which attaches stem and leaf	i) compound fruit ii) is a problem of pollination iii) the cotyledons break the seed coat iv) is called a leaf base v) the cotyledons donot come out of the soil vi) simple fruit vii) problem of pollination viii) process going

Answer:
a) In germination of pumpkin seeds the cotyledons break the seed coat.
b) In germination of mango seed the cotyledons donot come out of the soil.
c) Heat helps to keep our life process going.
d) Deforestation is a problem of pollination.
e) Excess use of insecticide is a problem of pollination.
f) Mango is a simple fruit.
g) Jackfruit is the example of compound fruit.
h) The part which attaches stem and leaf is called a leaf base.

Very Short Questions and Answers : (1 mark for each question)

Question 1.
How does the water goes to leaves of a tree?
Answer:
By xylem tissue.

Question 2.
How does the prepared food goes to the lower most parts of plants?
Answer:
By phloem tissue.

Question 3.
Where does plants store the excess food?
Answer:
In fruits, sometimses in modified shoots.

Question 4.
Which part of plant holds branches, leaves, flowers and fruits?
Answer:
Stem.

Question 5.
How does a plant protect itself from herbivorous animals?
Answer:
By spine.

Question 6.
On bright sunlight, absorbed water from soil, evaporates through leaf. Which part of plant can prevent it?
Answer:
Stomata of plant.

Question 7.
How do Bamboo, Banana and palm propagate and keep their existance on Earth inspite of not producing flowers and seeds?
Answer:
By Vegetative Propagation.

Question 8.
Puinshak, laushak can produce food without leaves. Which other part can they use to do the same purpose?
Answer:
They use stem or other green parts of plant which has cholorophyll.

Question 9.
Find out the occasions at home when wood is required.
Answer:
As fuel, to make door, windows, furniture.

Question 10.
Do you know how paper is prepared?
Answer:
From bamboo, grass etc. paper is processed in factory.

Question 11.
Which transport vehicles need wood to construct?
Answer:
Hand cart, bullock cart, small vehicles.

Question 12.
How do plants help in your household cooking?
Answer:
By supplying fuel, vegetables, spices.

Question 13.
Which stem do you use as food?
Answer:
Patatc ginger etc.

Question 14.
Name the part of plant to make jute bag or your dress.
Answer:
Stem of jute, seed cover of cotton.

Question 15.
From which plant part we can use to make gum, mosquito repellent, tyre of cycle and varnish?
Answer:
Excrete of plant that secretes from stem.

Question 16.
Name some medicines which can be obtained from stem?
Answer:
quinine, resarpin, cincona.

Question 17.
Which provide shelter to birds, squirel, bat, monkeys at night?
Answer:
Trunks of big trees.

Question 18.
Name some insects which live on plant.
Answer:
Caterpillar, silkworm, cricket.

Question 19.
Why woods are attacked by insects?
Answer:
Insects get their necessary foods.

Question 20.
Who emits essential oxygen? Who absorbs your exhaled CO₂?
Answer:
Leaves of plant.

Question 21.
Why do you feel cold under a canopy in summer?
Answer:
Due to transpiration of plant.

Question 22.
Who absorbs polluted air of vehicles and cleans the nature?
Answer:
Green plant and trees.

Question 23.
How can be said the age of a plant from its stem?
Answer:
Number of rounds inside a stem is counted to know the age of plant.

Question 24.
Name some helpful insects which use leaves as food.
Answer:
Silkworm.

Question 25.
Name some harmful insects which use leaves as food.
Answer:
Pine Bark Beette, aphid, ants.

Question 26.
Which leaves are consumed by elephant, deer, cow and goat?’
Answer:
Grass, peepal leaf, Banyan leaf etc.

Question 27.
Which leaf ribs are used in our daily house hold clearing?
Answer:
Coconut, date palm.

Question 28.
Which leaf juice or extract is used as medicine?
Answer:
Tulshi, Basaka, Pudina, Kalmegh.

Question 29.
Which leaves of plants man uses for his livelihood?
Answer:
Tobacco leaf, Sal leaf. Tea leaf.

Question 30.
Which leaves are used for fuel?
Answer:
Dried sal leaf, mango leaf, jack fruit leaf.

Question 31.
Which leaves are used to make wall or shed?
Answer:
Coconut leaf, Hogla leaf

Question 32.
Name some leaves which are used for decoration?
Answer:
Mango leaf. Tamarisk leaf.

Question 33.
Which flower shows sepals or petals similar in shape and size?
Answer:
Hibiscus, Dhatura.

Question 34.
Parts of calyx corolla are not similar in which flower?
Answer:
ApArajita, Balsam.

Question 35.
Which flowers show all the four whorls?
Answer:
Hibiscus, Dhatura.

Question 36.
Which flower shows the absence of one or more whorls?
Answer:
Cucurbits.

Question 37.
Does the colour of petals can change (with change in attitude, season, day time)?
Answer:
Lotus and land-lily remains white after blooming in morning as the sunrise they become pink.

Question 38.
Why the petals of a flower are red in somewhere, yellow in somewhere, purple in somewhere or blue in some place else?
Answer:
Due to presence of different coloured pigments.

Question 39.
How does a plant benefit from the scent of petals?
Answer:
The scant attracts insects, birds and animals which help in pollination.

Question 40.
Name the plants which are nocturnal and which bloom in day.
Answer:
Sandhyamalati, Juhi and Jasmine are nocturnal; Rose, Merrigold, Sunflower bloom in day time.

Question 41.
Can you name some animals which can consume pollens?
Answer:
Ant, bee, birds.

Question 42.
What are the problems do encounter if we inhale pollen?
Answer:
Breathing problem, allergy.

Question 43.
How can man use flower colours?
Answer:
To make different coloured dye.

Question 44.
What is the relation of sunlight with blooming?
Ansswer:
The heat and light of sunlight helps in blooming.

Question 45.
Which part of flower forms fruit?
Answer:
Ovum.

Short Questions & Answers : (2 marks for each question)

Question 1.
What are the function of stem?
Answer:

• Keeps the plant firm
• Carrier of food
• Preparing food in green parts of stem
• Holds the branches
• Spreading branches
• Bear flower and bud
• Bear fruit
• Co-ordinates with all parts of plant.

Question 2.
Leaves are green but why are the petals coloured?
Answer:
Leaves had chlorophyll which are green in colour. It is needed to produce food. But petals are coloured to attract insects and birds which helps in pollination.

Question 3.
What is diffusion?
Answer:
The phenomenon, in which molecules of a substance spread through a gas or a solution from a region of higher concentration to a lower one is called diffusion.

Question 4.
From where does the seed develop? From which part of the flower?
Answer:
Seed develop from the ovule after fertilization. A seed is formed as a result of fertilization of an egg with a male gamete within the embryo sac of an ovule of Gynoecium of a flower.

Question 5.
Give example to prove that animals differ in the sensitivity of their olfactory organs.
Answer:
Small flies Drosophila appear when fruits are cut, as flies can recognize the volatile compounds responsible for the sweet smell of fruits. On the other hand, volatile compounds in human sweat can be recognized by Anopheles mosquitoes which spread malaria fly towards us for sucking blood.

Question 6.
What is osmosis?
Answer:
Osmosis is the diffusion of water molecules across a semi-permeable membrane from more dilute solution (with a lower solute concentration) to a less dilute solution (with a higher solute concentration).

Question 7.
What is Pheromone?
Answer:
Numerous volatile organic compounds play a vital role in reproduction of various animals including insects, tiger, elephant, deer etc. These compounds are called ‘pharomones’.

Long Questions & Answers : (3 marks for each question)

Question 1.
Write down the functions of different parts of seed.
Answer:

• Seed Coat : The outer covering of the seed is known as seed coat. Seed coat protects the inner part of a seed.
• Embryo: the embryo may be defined as the young or miniature plant, enclosed within the seed-coat. It develops from the fertilized egg.
• Cotyledons : The cotyledons, are also known as seed leaves, they store food material for the embryo.
• Radicle : The part of the axis which projects out of the cotyledons is called the radicle. Radicle gives rise to the primary root.
• Plumule : It develops from the embroyonic axis and gives rise to the primary root.

Question 2.
Describe the different parts of a root.
Answer:

• Root cap zone : The cap like part at the tip of root is root cap. It protects the soft root tip from friction with soil particle when it enter the soil. This region is called root cap zone.
• Growth zone : The part adjacent to root cap region does not have any hair. This part helps the root to increase in length and enters the soil. This is the growth zone of root.
• Root hair zone : The part just above growth zone has many hairy appendages, it is the root hair zone. Plant absorbs water and soluble minerals from soil with the help of these root hairs.
• Permanent zone : The hard part present above root hair region is the permanent zone. It firmly keeps the plant in position in soil.

Question 3.
Define – Node, Internode, Axil.
Answer:

• Node: The place of origin of branches on stem is called Node.
• Internode: The place between two nodes is called Internode.
• Axil: An angle is formed, between leaf and stem, it is called Axil.

Question 4.
What are the different types of leaves?
Answer:
There are two types of leaves —

• Simple leaf: The margin of the leaf whose blade/lamina is entire i.e. it is not lobbed, such types of leaf is called Simple leaf. Example — ‘Peepul’ plant have only one leaf blade.
• Compound leaf: In some plants the leaf is directed in many parts upto its midrib. This type of leaf is called Compound leaf. Example — The leaf of tamarind plant.

Question 5.
How many parts are there in a flower?
Answer:
A flower consists of four part. Each of these parts is called a whorl. They are —

• Calyx
• Corolla
• Androecium
• Gynoecium

Calyx: This is the outermost whorl and floral leaves of this whorl are called sepals. Sepals enclose the bud and protect the inner whorls. Calyx is inverted bell shaped and green in colour.

Corolla: It is the second whorl of floral leaves which are called petals. Petals fuse together and make different shapes in different flowers. Any flower colour is the colour of its petals. Their shape, size, smell and colours are different in different flowers.

Androecium: Androecium is the third whorl and male reproductive organ of a flower. It has a slender thread like part called stamen and a kidney-shaped sac are called Anther at tip. The yellow powdery mass in sac are called Pollen Graind.

Gynoecium: Gynoecium is the innermost whorl of the flower. It is the female reproductive organ of the flower. Ovary, style and stigma together form Carpel. All the Carpel of a flower together form Gynoecium.

Question 6.
How many types of seeds are there depending upon the number of cotyledons present in a seed?
Answer:
The seeds are of two types —
(a) Monocotyledonous seed — Which have a single cotyledon in their seeds. They give rise to monocotyledonous plants like wheat, rice, maize, onion and barley.

(b) Dicotyledonous seeds — Which have two cotyledons in their seeds. They give rise to dicotyledonous plants like mango, gram, pea, castor etc.

Question 7.
How many types of pollination are there?
Answer: There are two types of pollination —

• Self Pollination : When pollen is transferred to the stigma of same flower or different flower of the same plant them it is called Self Pollination.
• Cross Pollination : When pollen is transferred to the stigma of a flower of different plant of same type, then it is called Cross Pollination.

Question 8.
List some facts that hamper pollination.
Answer:

• Excess use of insecticide reduces beneficial insects like honey bee.
• Temperature differences caused change in bloom timing, thus hampering pollinations
• Deforestation of trees like simul destroy the shelters of pollinating vectors like bats. Titus pollination gets hampered.

Question 9.
List the properties of diffusion.
Answer:

• Diffusion is faster in the gas phase than in a solution.
• Diffusion of heavier molecules is slower than that of the lighter ones.
• Diffusion is faster at higher temperatures.

Question 10.
Why do snakes frequently protrude their tongues?
Answer:
Molecules of different volatile compounds from different animal bodies spread through air, and get stuck to the tongue of the snake. The snake than withdraws the tongue and touches the palate with it. A special organ called Jacobson Organ in the palate receives the molecules of odour. This elicits sensation in its brain. From this the snake gets to know about its surroundings.

Question 11.
What is Germination? Define the two types of Germination.
Answer:
The process of forming plantlet from seed is called Germination.

• In germination of pumpkin, tamarind seeds the cotyledons break the seed coat and come out at the soil. It is called Epigeal Germination.
• In Germination of pea, grams or mango seed the cotyledons do not come out of the soil It is called Hypogeal Germination.

Question 12.
What is ORS?
Answer:
In case of loose motion, huge quantity of water comes out through liquid stool and urine. At that time, take a big glass full of water. Add three teaspoons of sugar and a pinch of salt in it. Now drink three such glasses through out the day. It will compensate up the loss of water and salt in your body. It is called Oral Rehydration Solution or ORS.

Question 13.
When sunstroke occurs? What should we do then?
Answer:
If deficiency of salt and water occur for a longtime on a summer day man can become senseless at that time, it is called sunstroke. Then the patient should be lied down, clothes should be loosned. Then he/she should drink cold water and bodies should sponged in cold water also.

Question 14.
How do salt water and sweet water fishes maintain the water and salt level in their body?
Answer:
Sweet water fishes i.e. fishes of pond or river absorbs salt from water and excrete excess water out. On the other hand saline water fish excrete scanty water, they put excess salts out to maintain water and salt balance in their body.

Detailed explanations in West Bengal Board Class 7 Science Book Solutions Chapter 7 Crisis of Environment, Plants and Conservation offer valuable context and analysis.

WBBSE Class 7 Science Chapter 7 Question Answer – Crisis of Environment, Plants and Conservation

(Page no. 227)

Question 1.
What is happening in the pictures given above? Write down the reasons behind them.
Answer:
Storm, Oceanic high tide, melting of snow cap in polar regions, flood, landslides. These occur due to increasing environmental pollution.

Question 2.
Now write the difference between Weather and Climate.
Answer:

Weather	Climate
1. Weather is a day-to-day atmospheric condition.	1. Climate is the average of weather condition for a long period (years)
2. Weather reflects changes of every day every hour even in every moment.	2. Climate reflects condition of a definite specific period of time.
3. Weather is an atmospheric condition of a small place. Weather of two nearly places can be different.	3. Climate is the weather condition of a vast region.

(Page no. 228)

Question 1.
What are the important factors on which weather and climate depend?
Answer:

• Temperature of atmosphere.
• Humidity of atmosphere
• Rainfall.
• Snowfall.
• Movement of wind.
• Ocean current

Try to answer the following question:

1. When do buds appear in a mango tree?
Answer:
In Spring season.

2. When do migratory birds visit our country from abroad?
Answer:
During winter season.

3. When do the Husa fishes lay eggs?
Answer:
In Rainy season.

4. When does Palash bloom?
Answer:
In Spring season.

5. Write the name of some natural phenomena which occur in a definite time of the year.
Answer:

• Merrigold blooms in winter season,
• Sunflower blossoms in summer season.
• Suli flower blossoms autumn season.
• Cabbage and Cauliflower vegetables grow only in winter season.

6. In which time of the year, is our country very warm.
Answer:
Summer season.

7. Do you know the name of any other season apart from Summer, Monsoon, Autumn and Winter?
Answer:
Spring.

8. Does Monsoon arrive at a definite time in every year?
Answer:
Now dueto imbalance in ecosystem as a result of environmental pollution monsoon arrive late than the expected time.

9. How long does the winter stay?
Answer:
For three months.

What can happen if seasons stay for a longer or shorter period of time? Fill up the table below :
Answer:

Name of the season	Problems due to its longer or shorter stay
1. Summer	1. Due to longer stay of summer the water bodies dry up, there is scarcity of water, draught occurs, production of crop is hampered.
2. Rainy	2. Due to heavy rain flood and landslide occur, scanty rain affects the production of rice and other crops
3. Winter	3. If winter stays shorter then the production of vegetables will be affected mainly the production of potato will be hampered.
4. Spring	4. If Spring stays shorter ecological balance will be hampered as in spring many new plants grow and it is mating season of animal world.

(Page no. 129)

Worksheet

1. What is your name? Sufal Mahoto
2. How old are you ? 55 years
3. Write the name of your locality and mention the characteristics of weather of your locality –
Answer:
Midnapore, it is very hot in the month of May, monsoon comes here in June-July months, winter seasons are December and January.

Question 4.
What are the changes that you have experienced in the climatic conditions (temperature, rainfall etc.) in comparison with your childhood?
Answer:

• Average amount of rainfall has decreased
• Temperature had exceeded than before.
• Summer has become very severe than before and it lasts longer than past.
• Winter season remains for shorter period than before.

Question 5.
What are the differences of present day climate with that of 20 years earlier?
Answer:

• Duration of winter season has decreased than before.
• Due to deforestation summer lasts longer and it had become unbearable and severe.
• Average Rainfall is less than before.
• Spring season lasts for shorter time

Question 6.
What can be the reasons behind these changes?
Answer:

• Deforestation.
• Establishment of factories in large number has polluted the atmosphere.
• Excessive use of petrol and diesel vehicles.
• Brick built houses has increased which has lead to increase in temperature.

Question 7.
Do you know about any physical problem that arises due to these changes?
Answer:

• Indigestion and other diseases regarding stomach.
• Skin problem.
• Cancer in various parts of body.
• Asthma and rise in blood pressure.

Question 8.
Trace out different problems (other than physical problems) of your locality due to climatic changes.
Answer:

• Production of food crop has decreased.
• There is scarcity of drinking water as the water of lakes and ponds has become polluted.
• Temperature has increased.
• Flood occurs frequently.

Question 9.
What can be done so that the climatic change do not cause major disruptions?
Answer:

• Afforestation.
• Use of unbaded petrol and of CNG (Compressed Natural Gas) in automobiles.
• installation of tall chimneys in factories and fitting them with filters to prevent pollution.
• Decreasing the number of vehicles on road.

(Page no. 230)

(i) What do you see from the above pictures?
Answer:
Pollution of environment.

(ii) Where does the emitted gases from various sources go?
Answer:
In the atmosphere.

(Page no. 233)

Find out different news on global warming and write them down briefly.

Topic	News
1. Melting of the glaciers.	I. It will cause swage of water in the rivers nourished by the glaciers and then the water will decrease resulting in severe water crisis.
2. Rise in sea level.	2. The coastal areas may become flooded. There will be loss of life and huge economic loss.
3. Destruction of biodiversity.	3. Many marine animals and fishery resources in the oceans and seas will be come extinct, ecological balance will be hampered.

(Page no. 235)

Make a list of the organisms that live near your school or home. If you have seen any organism in other places, then include them in the following list.

Nature of habitat	The plants that you saw (Herb/Shrub/tree)	The animals that you see (vertibrate/invertebrate)
1. Wet land	grass, water-lily, moss.	snake, frog, snail.
2. Wet dyke	moss, small bushes.	Earth-warm, Centipede, Scorpion

Nature of habitat	The plants that you saw (Herb/Shrub/tree)	The animals that you see (vertibrate/ invertibrate)
3. Dense bush near a pond	Sandhyamalati, Aakando. Dhatura	Mongoose, Rat, water bird.
4. Rathole	—	Rat
5. Hole in the thick trunk of a tree.	creepers, mosses	owl. squirrel
6. Termite Hill	grass	Termite, Ant
7. Cracks on the bricks of an old house	Peepal, planting, climbers.	bat; pigeons
8. Roof top of house	—	lizard, behive.
9. Garden	Rose plant, Jasmine, Hibiscus grass, coconut tree.	Cameleon, squirrel, crow, cuckoo, wood pecker

(Page no. 237)

Question 1.
Do we get any benefit from all these animals and plants? Let’s write them down. You can add some other plants and animals to this list.
Answer:

Name of plant	Benefits animal	Name of animal	Benefits
1. Paddy	Services as main food crop for human beings.	1. Panchax fish	serves as food for acquatic animals and birds.
2. Banyan	Gives cool shade, leaves are eaten by animals, birds builts nests.	2. Snake	Eats different harmful insects.
3. Neem	leaves have medicinal value, wood is very useful.	3. Bat	Eats different harmful worms and insects.
4. Coconut	fruit is eaten and also used to make different dishes leaves are useful to make broom, rope, wood is useful	4. Crow	Eats rotten things, dead things and helps to keep our environment clean

(Page no. 241)

Question 1.
Reasons for loss of bio-diversity of earth: Reason for loss of habitat
Answer:

• Deforestation to meet the requirement of wood.
• For increasing demand of agricultural land.
• To increase the habitat area of human being.
• Establishment of industries and factories.

Question 2.
What will happen if The Sundarban is wiped out to meet the requirement of wood?
Answer:
The Sundarbans is natural habitat of many wild lifes especially of Royal Bengal tigers. They will become extinct. We get wax and honey from this forest area that will also not be available. It is a famous tourist spot. So a great source of income from tourism will also come to and end.

Question 3.
Let’s make a list of different animals who fall prey to the greed of the poachers.
Answer:

Substance obtained by killing the animal	Animal killed for getting the  substance	Use of those parts	How can we obtain these subtances without killing the animals.
1. Teeth	Elephant	decorative items	when the animal dies.
2. Hide	Tiger, Lion, Rhinocerous	garments, bag, drum	when the animal dies naturally
3. Horns	Deer	decorative items	can be created artificially
4. Fur	Bear, Sheep	garments, shawl	can be made artificially
5. Musk	Deer	perfume	When the animal dies naturally

(Page no. 242)

Question 1.
What will happen if The number of tiger or other big carnivores decreases significantly in a forest:
Answer:
The ‘food web’ and the flow energy in the different level of animal will get hampered. This will destroy ecological balance.

Question 2.
What will happen if some fishes were introduced in a pond which eat other small fishes.
Answer:
Small fishes will become extinct. These fishes are valuable source of nutrients to our body

(Page no. 243)

Question 1.
What will happen if The amount of rainfall decreases in a certain region?
Answer:
The trees and plants of that area will dry up, agricultural production will be hampered, soil will become dry leading to soil erosion, there will scarcity of drinking water.

Question 2.
What will happen if Industrial waste is poured into the river water?
Answer:
The water will become contaminated, this can spread different diseases, the fishes and other acquatic animals will die.

(Page no. 244)

Question 1.
What will happen in case of large-scale exploitation of a plant that is a source of medicine
Answer:
Then a time will come when that plant will not be available to us any more, so the medicine will not be available as a result the disease will become uncurable.

(Page no. 245)

Wastes and Risks to Human Health :

• Contaminated water.
• Smoke from factories.
• Pesticides in fruits and vegetables.
• Unbygenic condition inside factories.
• Municipal waste causing choking hazard in street animals.
• Plastic bottles and packets daily waste in our day-to-day life.

Mention the nature and components of different wastes shown in the picture.

SI. No	Source of waste	Nature of waste (solid/liquid)	Component of waste
1.	Sewage	liquid waste from domestic activities	Kitchen waste, toilet and other household waste waters.
2.	Factories	gaseous pollutants	CO2, SO2, and CO and also oxides of nitrogen.
3.	Pesticides	solid	pesticides in veg­etables and fruit.
4.	Factories	Solid, gaseous	pieces of glass, plastic, chemicals
5.	Rural and Urban areas	Solid, liquid, gas	rotten things bottle, plastic
6.	Dumping ground of waste.	Solid, liquid	plastic bags, glass, bottles, plastic, rotten things:

(Page no. 246)

Make a list of different wastes from different sources and trace their nature.
Answer:

Source	Name of the waste product	Nature of waste product
1. School	torn paper, broken pen, pencil, polythene.	snake, frog, snail.
2. Rice Mill	Husk of paddy, ashes	solid
3. Pond	dirty water, cleaning agent like detergent, soap.	solid; liquid
4. Agricultural	chemical fertilizer, pesticide, straw, husk	solid
5. Hospital	Syringe, cotton. wrapped of medicine, bottle.	solid
6. Hospital	Syringe, cotton, wrapper of medicine, bottle.	solid
7. Playground	plastic bottle, torn papers	solid
8. Bus stand	shell of ground nut, torn paper, bottles	solid
9. Houses	peel of fruit and veg­etable, torn clothes paper, bottle.	solid

(Page no. 247)

Diseases are as follows :

1. Infectious diseases spread by vectors (Mosquito fly, rat, cat, dog)-Malaria. Filaria. Dengue, Diarrhoea, Plague, Diptheria. Rabies)
2. Infectious diseases spread by used clothes of patients of hospitals – Hepatitis, Jaundice, Phenuiuonia, Malaria, Tuberculosis
3. Infectious diseases spread by different untreated compound or metals of factories – Cancer, nervous disorder, pain in bones, skin disease, lungs problem, Asthma.

Have you noticed symptoms of such disease in people known to you? Write it down.
Answer:

Where does he work	What can be the reason	What is the problem	What to do
1. Asbestos factory	Asbestos	Pulmonary problem	Should consult doctor
2. Cement factory	powder of cement	Pulmonary problem	Should consult  doctor
3. Pesticide factory	Smell of chemicals	Breathing Problem, consult Cancer	Should consult doctor
4. Alcohol factory	Alcohol	problem relating to stomach, problem of indigestion	Should consult doctor

Now find out what unhealthy habits or reasons are responsible for these diseases or risks of diseases
Answer:

Disease/Risk	Cause	Which unhealthy nature/lack of precaution is responsible	What to do
Hepatitis	Viral infection through water	Drinking polluted water	One should drink boiled water
Malaria	Bite of Mosquito	Sleeping without mosquito net	One should sleep inside mosquito net instead of only using mosquito coil
Cholera	Virus in drinking water	Drinking polluted water, coming in contact with disease person	One should boil water before drinking
Plague	Rats	Not killing rats inside shops and houses.	We should keep our house and shop clean,

(Page no. 249)

Teacher showed these pictures to the students and asked to complete the following table on role of plant in one’s life.
Answer:

What will happen if there are no plants	What will happen if plants are present
1. Environmental pollution.	1. Rainfall will occur.
2. Draught and flood occur.	2. Oxygen supply increase so the greenhouse effect will decrease.
3. Green house effect increases.	3. Supply of food remains.
4. Scarcity of food.	4. Ecological balance remains.
5. Ecological balance becomes disturbed.	5. Stops soil erosion.
6. Rainfall will decrease.	6. We gel life saving medicine.

(Page no. 250)

Describe how do the following animals depends on forest plant for food.
Answer:

Name of the animal	Food and their sources	Does they get same amount throughout the year	What will happen if sources are lost
Dear	grass, leaves	No. it decreases during summer	supply of food will be hampered
Elephant	leaves	No, decreases in summer	supply of food will be hampered
One horned Rhino	grass, small shrubs	No	may die in absence of food.
Bat	fruits	Yes	may extinct
Squirrel	fruits and nuts	Yes	shortage of food
Hornbill	Cereals	Yes	will die
Red Ponda	leaves of Bamboo	No	shortage of food
Monkey	leaves, fruit flower, root	No	supply of food will be hampered
Goat	leaves, gram	Yes	shortage of food

Answer:
1. Nectar of flower → Bee → Lizard → Eagle
2. Leaf → Deer → Tiger
3. Rotten leaves → Fish → Civet cat
4. Twig → Elephant
5. Grain → Small bird → Hawk

Now construct different food chain from the following plants and animals.
Grass. goat. small fishes. boal fish. Kingfisher. Crane. Kite. Rat. Hawk. Rice plant, Stem borer, Hen. Leopard, Zebra. Lion, Rhino, Tiger.

SI. Organisms of food chain No.	Shape of food chain
1. Grass → goat → Lion	Forest food chain
2. Rice plant → Rat → Kite	Grassland food chain
3. Stem borer → Zebra → Leopard	Forest food chain
4. Small fish → boal fish → Crane	Acquatic food chain
5. Rice plant → Hen → Hawk	Grassland food chain

(Page no. 253)

If there is any mango/banyan/peepul/simul/tamarind tree near your home, then notice that which animals are living there.

1. Insects — Grasshopper. Honey bee
2. Birds — Bulbul, owl, crow
3. Mamais — Bat, Monkey
4. Reptiles— Snake, Chameleon, Lizard

(Page no. 254)

If one plant can give shelter to all these animals then you can understand that how many animals can live in a forest. Now can you say which animals live in the following forests —

1. Coniferous forest — Snow Leopard, Elephant, Snake, Tiger.
2. Deciduous forest — Tiger, Lion, Rhinoceros, Elephant.
3. Mangrove forest — Tiger, Deer, Crocodile, Bee, Birds.
4. Grassland forest — One-horned Rhino, Deer, Zebra, Giraffe
5. Weed forests of wetland — Mongoose. Civet cat, Iguana.
6. Bushes and trees around your house — Iguana, Cat, Frog, Snake. Squirrel.

Many animals are becoming extinct on earth due to loss of plant. Name some of these animals which depend exclusively on plants.

Name of the animal	Depends on plant for food/shelter
1. Adjutant stork 2. Owl 3. Civet Cat 4. Langur	peepal Mango Tamarind Arjun, Banyan

Class 7 Science Chapter 7 Question Answer West Bengal Board – Crisis of Environment, Plants and Conservation

Multiple Choice Questions & Answers : (1 mark for each question)

Question 1.
The ability to absorb CO₂ in different plants is ……………….
i) same
ii) different
iii) may be same, may be different
Answer:
ii) different

Question 2.
Corals become affected due to the increase in ……………….
i) acidity
ii) temperature
iii) acidity and temperature
Answer:
iii) acidity and temperature

Question 3.
Indiscriminate use of chemicals can bring about the destruction of ……………….
i) animals
ii) plants
iii) animals and plants
Answer:
iii) animals and plants

Question 4.
Trees of a jungle are felled ……………….
i) to produce luxury materials
ii) for increasing agricultural land
iii) to increase the habitable areas
iv) all are true
Answer:
iv) all are true

Question 5.
Musk is obtained by killing ……………….
i) deer
ii) elephant
iii) bear
iv) sheep
Answer:
i) deer

Question 6.
Hide is obtained by killing ……………….
i) elephant
ii) bear
iii) tiger
iv) sheep
Answer:
iii) tiger

Question 7.
Horns of deer are used for……………
i) decorative items
ii) medicine
iii) perfume
iv) garments
Answer:
i) decorative items

Question 8.
Reserpine is received from ……………
i) Penicillium
ii) Rauwolfia
iii) Basil
iv) Cinchona
Answer:
ii) Rauwolfia

Question 9.
The habitate of grass, moss, water-lily is ……………
i) near a pond
ii) termite hill
iii) wet dyke
iv) wet land
Answer:
iv) wet land

Question 10.
The ice cover of Alaska Bay adjoining the North Pole has reduced by 40% in the last ……………
i) 10 years
ii) 30 years
iii) 20 years
iv) 40 years
Answer:
ii) 30 years

Question 11.
The average temperature of earth had increased by 1°C in last ……………
i) 100 years
ii) 50 years
iii) 200 years
iv) 150 years
Answer:
i) 100 years

Question 12.
More than 99% of the glacieric are present in ……………
i) North poles
ii) South poles
iii) North and South poles
Answer:
iii) North and South poles

Fill in the blanks : (1 mark for each question)

1. …………… is an atmospheric condition which changes every day, every hour even in every moment.
Answer:
Weather

2. …………… is the average of weather of a particular area for a long period (years).
Answer:
Climate

3. Climatic changes have an important correlation with ……………
Answer:
global warming.

4. CO₂ is one of the important gases produced by …………… activities.
Answer:
anthropogenic

5. The biggest source of fresh water on the earth is ……………
Answer:
glaciers

6. More than …………… of the glaciers are present in North and South poles of earth.
Answer:
99%.

7. The …………… nourishes nine big rivers of Asia.
Answer:
Himalayas

8. …………… is the shelter for the largest clan of the world.
Answer:
Sunderbans

9. …………… is a type of marine invertebrate animal.
Answer:
Coral.

10. The biodiversity of our country is so rich that India is termed as a …………… Nation.
Answer:
mega diversity.

11. We get Quinine from ……………
Answer:
Cinchona.

12. Ranwolfia medicine is derived from ……………
Answer:
Keserpine.

State whether True or False : (1 mark for each question)

1. Climate is the average for small period of time.
Answer:
Flase

2. Hilsa fish lay eggs in the rainy season.
Answer:
True.

3. Climatic changes does not have any relation with global warming.
Answer:
False.

4. Some glaciers are also found in Himalayas.
Answer:
True.

5. Sea level may fall due to the melting of these glaciers.
Answer:
False.

6. The coastal areas may become flooded if the sea level rises.
Answer:
True.

7. Glaciers reflect nearly 20% of the sunlight and absorbes 80 of it.
Answer:
False.

8. Coral exoskeleton is made up of sodium bicarbonate and it protects the body.
Answer:
False.

9. Dead corals and other organic materials help in forming the coral island.
Answer:
True.

10. The temperature of Indian Ocean have risen due to global warming.
Answer:
True.

11. India is the habitat of 30% of all the plants of the world.
Answer:
False.

12. Introduction of Tilapia and giant African magur in the ponds of rural Bengal posed a huge problem for the existence of indigenous fishes.
Answer:
True.

Match the column A With column B.

Column A	Column B
a) Coral reefs are in danger b) Glaciers reflect nearly 80% c) 2005 was the warmest year d) Weather of two nearby places c) Some gases are naturally produced f) Some glaceries are found g) In 1988 nearly 16% of corals h) Bengal vulture is i) Hepatitis is a j) The plant with greater surface area	i) in the atmosphere ii) of the world were lost forever iii) of leaf absorb more CO2 iv) due to global warming v) viral infection vi) on the verge of extinction vii) of sunlight viii) can be different ix) in the Himalayas x) in the last century

Answer:
a) Coral reefs are in danger due to global wanning.
b) Glaciers reflect nearly 80% of sunlight.
c) 2005 was the warmest year in the last century.
d) Weather of two nearby places can be different.
e) Some gases are naturally produced in the atmosphere.
f) Some glaceries are found in the Himalayas.
g) In 1988 nearly 16% of corals of the world were lost forever.
h) Bengal vulture is on the verge of extinction,
i) Hepatitis is a viral infection.
j) The plant with greater surface area of leaf absorb more CO₂

Very Short Questions & Answers : (1 mark for each question)

Question 1.
Which animal eat the egg of the turtle in Galapagos Island?
Answer:
Dogs and pigs used to eat the eggs of the turtle.

Question 2.
From which country Tilapia and giant Magur came?
Answer:
They came from Africa.

Question 3.
Name three fishes which are on the verge of being extinct?
Answer:
Mourala, Punti, Khalse.

Question 4.
The polar ice caps are melting, why?
Answer:
Due to global warming.

Question 5.
Name some animals that live in the Coral reefs.
Answer:
Fishes, molusca, echinodermata, sponge, Crustacea etc animals live in the coral reefs.

Question 6.
What is Global Warming?
Answer:
Due to unplanned human activities the amount of carbon dioxide and other gaseous compound in the atmoshere are increasing. This gaseous substances in turn retain the excess heat on earth. As a result, the temperature of earth increases than what is normal. This is Global Warming.

Question 7.
Name some gases which are present in smoke emitted from different sources.
Answer:
Carbon dioxide (CO₂), Methane (CH₄), Nitrous Oxide (N₂O). Chloro-Fluoro-Carbon. Sulpher di-oxide (SO₂) and particles of dust, Carbon etc.

Question 8.
Name some animals which are on the verge of extinction?
Answer:
Royal Bengal Tiger, Bengal Vulture. One-horned Rhinoceros. Gangetic Dolphin. Cheetah, Chimpanzee, Orangutan and Gorilla.

Long Questions & Answers : (3 marks for each question)

Question 1.
What is Coral? Write a short note on it.
Answer:
Coral is a type of marine invertebrate animal. It be longs to the Phylum Cuidaria. They live together by forming colonies. They form an exoskeleton surrounding their body. This exoskeleton is made up Calcium Carbonate which protects the body. The exoskeletons are very colourful and have high demand in the fields of making of fancy items and jewelleries.

Question 2.
What is Food Chain?
Answer:
Green plants trap solar energy and make their food by photosynthesis. Animals cannot make their own food, so they obtain energy by eating plants or by eating animals which have eaten plants. This predator-prey relationship is called food chain.

Question 3.
What do we get from biodiversity?
Answer:

• Diversity of food crops helps us to get all kinds of nutrients necessary to our body and also helps to increase agricultural production.
• Plants and micro-organisms can absorb CO₂, and maintain O₂ – CO₂ balance in environment.
• Rooted plants increases the water retention capacity of the soil and also sustain the rainfall by returning back the excess water in the form of water vapour.
• Fungi and bacteria help in maintaining the level of nutrients present in the soil.
• Biodiversity of plants is a source of life saving medicine, wood, and other industries like silk industry, Lac industry etc.

Question 4.
What are the reasons of loss of biodiversity of earth?
Answer:
The reasons behind the loss of biodiversity of earth are as follows —

• Deforestation is done to meet the requirement of wood agricultural land and habitat area for human beings, so other organisms are losing their habitat.
• Illegal hunting or poaching is done to get teeth, hides, horns, fur and other body parts of animals. This greed is responsible for endangering the lives of different animals.
• If an organism cannot adapt with the climatic changes its existence will be in question. Animals like Emperor Penguin, Polar Foxes, Polar Bears are endangered due to melting of ice in polar region.
• Increasing environmental pollution is another reason for destruction of animals and plants.
• If some plants or animal is economically important then excessive use of them can be dangerous for their existance.

Question 5.
Name four Biodiversity hot spots of India.
Answer:

• Eastern Himalayas : Sikkim, Darjeeling, Dooars and Terai region.
• Western Ghat and Srilankas: The hilly forest region along the western coast of India.
• Indo-Burma: North-eastern states of India (e.g.: Meghalaya, Arunachal Pradesh)
• Sundaland : Andaman -Nicobar region of India.

Question 6.
How is plant helpful to us?
Answer:

• Due to plants water cycle remains on earth.
• Temperature of environment is controlled by plant.
• Velocity of storm is checked by plant.
• Environmental Pollution is prevented by plants.
• Plant stops soil erosion.
• Plants provide shelter of organisms.

Detailed explanations in West Bengal Board Class 7 Science Book Solutions Chapter 3 Atom, Molecule and Chemical Reaction offer valuable context and analysis.

WBBSE Class 7 Science Chapter 3 Question Answer – Atom, Molecule and Chemical Reaction

(Page no. 85)

Try to write the symbols from names of elements given below in the first two tables.

table 1

Name of Element	Symbol
Aluminiun	Al
Nickel	Ni
Arsenic	As
Silicon	Si
Zinc	Zn
Boron	B

table 2

Name of Element	Latin name	Symbol
Tin	Stannum	Sn
Mercury	Hydrogirum	Hg
Lead	Plumbum	Pb

Now we will learn the names and symbols of elements that originate from the names of famous scientists, the place of discovery, the native country of the discoverer or some planet.

(Page no. 87)

Now fill up the following table using the diagram for atomic structure of Helium atom as shown on the previous page.

Impact the diagrams above and fill up the following table :

(Page no. 88)

Fill up the following table with help from your teacher, if necessary.

(Page no. 89)

Discuss among yourselves and fill up the following table :

Write the valencies of radicals from the number of Sodium or Potassium atom.

(Page no. 90)

Now we shall determine the valencies of different metals and non-metals from their compounds with Chlorine. The number of Chlorine atoms which combine with an atom of an elements is the valency of that element.

(Page no. 92)

Symbols and valencies of some elements are given below. Write down the formula of the compounds by using the above procedure.

Discuss among yourselves and fill up the following table using the valencies of elements and radicals.

(Page no. 93)

Now discuss among yourselves and fill up the following table.

(Page no. 97)

Discuss among yourselves and balance the chemical equations by putting suitable numbers in the blank places (. . .) in them

Write the names and formula of products and balanced equations of the reactions by discussing among yourselves.

Discuss anong yourselves and write the formula (e) of missing product (s) in each case.

(Page no. 100)

Discuss among yourselves and write the type of reaction against each equation in the table.

Class 7 Science Chapter 3 Question Answer West Bengal Board – Atom, Molecule and Chemical Reaction

Multiple Choice Questions & Answers : (1 mark for each question)

Question 1.
Symbol of Arsenic is-
i) Ar
ii) As
iii) An
iv) Ac
Answer:
ii) As

Question 2.
Symbol of Mercury is-
i) Mc
ii) Me
iii) Mu
iv) Hg
Answer:
iv) Hg

Question 3.
Symbol of Lead-
i) Pb
ii) Ld
iii) Le
iv) Pm
Answer:
i) Pb

Question 4.
Formula of Lead Chloride is-
i) pbCl
ii) pbCl³
iii) pbCl₂
iv) pbCl₃
Answer:
iii) pbCl₂

Question 5.
Formula of Ferric Chloride is-
i) FeCl₂
ii) FeCl₃
iii) FeCl³
iv) FeCl²
Answer:
ii) FeCl₃

Question 6.
Formula of Potasiam Chloride-
i) KCl²
ii) KCl₂
iii) PCl
iv) KCl
Answer:
iv) KCl

Question 7.
Formula of Cupric Chloride-
i) CuCl₂
ii) CuCl
iii) CuCl²
iv) CuCl₃
Answer:
i) CuCl₂

Question 8.
Formula of Sodium Sulfate is-
i) NaSO
ii) NaSO₄
iii) Na₂ SO₄
iv) Na₂ SO₂
Answer:
iii) Na₂ SO₄

Question 9.
Formula of Aluminium Oxide is-
i) AlO₃
ii) Al₂ O₃
iii) Al₂ O₂
iv) AlO
Answer:
ii) Al₂ O₃

Question 10.
Formula of Silver Chloride is-
i) AgCl₃
ii) AgCl₂
iii) Ag₂ Cl
iv) AgCl
Answer:
iv) AgCl

Fill in the blanks : (1 mark for each question)

1. Formula of Magnesium Chloride is ______.
Answer:
MgCl₂

2. The atomic number of an element is 6 and mass number is 12 then the number of neutrons in nucleus would be ______.
Answer:
6.

3. In L orbit maximum _____ electrons can revolve.
Answer:
8 .

4. In compound P₂ O₅ the valency is ______.
Answer:
5.

5. Symbol of Aluminium Oxide is ______.
Answer:
Al₂ O₃.

6. Atomic weight of carbondioxide is ______.
Answer:
44.

7. In chemical equation the atomic number of both sides are ______.
Answer:
equal.

8. Symbol of Silver is ______.
Answer:
Ag.

9. Valency of Carbon is ______.
Answer:
4.

10. Mass of one electron particle is ________ of one Hydrogen atom.
Answer:
1 / 1837.

State whether True or False : (1 mark for each question)

1. Hydrogen reacts with nitrogen to produce ammonia.
Answer:
true

2. Chemical reaction is of one type.
Answer:
false

3. Ammonia is formed by the reaction of nitrogen and hydrogen.
Answer:
true

4. Mercury and oxygen are produced when mercuric oxide is heated.
Answer:
true

5. Formula of Ferric Oxide is Fe₂ O.
Answer:
false

6. Slacked lime is produced by the reaction of water with quicklime.
Answer:
true

7. Water is produced by chemical combination of oxygen and hydrogen.
Answer:
true

8. The formula of hydrogen sulfide is H₂ S₂.
Answer:
false

Short Questions & Answers : (1, 2 marks for each question)

Question 1.
What is the meaning of Greek word ‘Atom’?
Answer:
Meaning of the word ‘Atom’ is indivisible.

Question 2.
What is atom?
Answer:
The smallest particle of an element that retains the properties of the element is called an atom.

Question 3.
What is the mass number of an atom?
Answer:
The total number of protons and neutrons in the nucleus of atom is called the mass number of that atom.

Question 4.
What is Atomic Number?
Answer:
The number of Protons present in the nucleus of an aton of an element is known as the Atomic Number of the element.

Question 5.
What is Mass Number?
Answer:
The total number of Protons and Neutrons present in the nucleus of an atom of an element is known as the Mass Number of the element.

Question 6.
What is the difference between H₂ and 2H ?
Answer:
H₂ means 2 atoms of Hydrogen and 2H mears 2 molecules of Hydrogen.

Question 7.
Write the name of an element whose atom has no neutron.
Answer:
Ordinary Hydrogen atom or Protium.

Question 8.
What is the largest number of electron in K orbit?
Answer:
The largest number of electron in K orbit is 2 .

Question 9.
What is the atomic number of Helium?
Answer:
The atomic number of Helium is 2 .

Question 10.
How do the atoms exists in molecules?
Answer:
Ator exists in combined state.

Question 11.
Write the symbols of Potassium and Mercury.
Answer:
Symbol of Potassium is K and Mercury is Hg.

Question 12.
Who founded the theory of Molecules?
Answer:
Amedeo Avogadro.

Question 13.
What is total number of Natural Element?
Answer:
92.

Question 14.
What is ti.e molecular atomicity of Phosphorus.
Answer:
4.

Question 15.
What is tlit valency of Phosphate (PO₄) ?
Answer:
Valen y is 3.

Question 16.
If the orbit gues away from nucleus what would happen, will the number of electron increase 0 – decrease?
Answer:
Nurber c elect:on would increase.

Question 17.
W at is :ine charge of Nucleus?
Answer:
Pusitive.

Question 18.
A + B = Carbond 1 oxice, write the reacting element A and B of this reaction.
Answer:
A is Carbon (C) and : 3 is Oxygen (O₂)

Question 19.
Why the symbol of iron is Fe?
Answer:
The Latin nam: of iron is Ferrum. So the symbol is taken as Fe.

Question 20.
What is the total number of atoms in molccule of Ammonia?
Answer:
In Amonia (NH₃) molecule, the number of atoms are 4.

Question 21.
Which elements have zero valency?
Answer:
Non-reacting elements like inert gases (He, Ni, Ar etc.) have zero valency.

Question 22.
Name the element and the radical whcih have same valency.
Answer:
The element Sodium (Na) and radical Nitrate (NO₃) have same valency.

Question 23.
Can we say Neutron that is the main constituent of fromation of atoms of all substances?
Answer:
No, we cannot say that neutron is the main constituent.

Question 24.
What is the valency of Nitrogen in compound Ammonia?
Answer:
Valency of Nitrogen is 3 in Ammonia- (NH₃).

Question 25.
What is the charge of Electron?
Answer:
Negative.

Question 26.
When we can say an equation is balanced?
Answer:
If the number of atoms of each element on the left hand side is equal to the number of atoms of that element on the right hand side, then we can say that the equation is balanced.

Long Questions & Answers : (3 marks for each question)

Question 1.
What is symbol? Give example.
Answer:
When the name of an element is represented by a single letter or two letters of english alphabet it is called symbol of that element. By using symbol we can express briefly an atom. As example – symbol of Aluminium is Al, symbol of Mercury is Hg.

Question 2.
What is sign?
Answer:
The way of expressing briefly the molecules of elements and compounds is called sign. For example –
Carbon-di-oxide (CO₂), Sulphur-di-oxide (SO₂). Nitric Oxide (NO).

Question 3.
Explain the process of writing symbols.
Answer:
(1) For some elements the first letter of the name of the element written in capital. is used as Symbol.
Example: H – Hydrogen, O – Oxygen,
S-Sulphur, \quad N-Nitrogen.

(2) When there are two or more than two elements whose names start with the same alphabet. the elements are given a two-letter symbol. The first letter of the symbol is the first letter of the name of the element, written in small letters.
Examples –
B – Boron, Be- Beryllium, Br- Bromine

(3) The symbol of each element is written in capital letter.
Example –
Carbon -C, Oxygen -O, Nitrogen -N.
(4) The symbols of a few elements are derived from their Latin names.
Examples –
Sodium – Na (derived from latin name Natrium); Iron – Fe (latin name Ferrum).

Question 4.
What is an element?
Answer:
A element is a pure substance that is made up of identical minute particles called atoms. Elemelits cannot be split into two or more simplers substances by chemical methods. There are only about 114 elements known till date, out of which 92 are found in nature.

Question 5.
What is molecule?
Answer:
Atoms sometimes exist alone but more often they combine with other atoms of the same or different kind. A group of atoms formed by the combination of atoms is called a molecule. A molecule can exist by itself. A molecule may contain similar or dissimilar atoms.

Question 6.
How many particles are there in an atom?
Answer:
Three types of particles are present in an atom –
i) Proton,
ii) Electron,
ii) Neutron.
(-) Indicates particles called Proton. These are charged with positive electricity or positively charged particles.
(O) Indicates particles called electrons. These are negatively charged particles.
( ) Indicates particles called Neutron. They have no electricity.

Question 7.
What is nucleus? Where do the electrons revolve?
Answer:
The Protons and Neutrons are grouped at a tiny place in the center of an atom. This place is called nucleus of an atom.
Electrons revolve in differenrt paths around the nucleus. The paths around the nucleus in which electrons can revolve are called orbits.

Question 8.
What are ions?
Answer:
The atoms whcih attain positive or negative charges due to gain or loss of one or more electrons are called ions.
The positively charged ions formed by the loss of electrons from an atom are called cations. The negatively charged ions formed by the gain of electrons by an atom are called anions. As example Na^{+is a cation and Cl^{-is an anion.

Question 9.
What are radicals?
Answer:
Sometimes one or more than one atom of same or different elements assemble of to form ions. These are called radicals. These radicals participate in chemical reaction in such assembled condition.
As example – Radical Lead (Pb⁺²)., Radical Nitrate (NO₃ ^–)

Question 10.
What is Valency?
Answer:
The capacity of elements to combine with each other is called their valency.
Valency is equal to the number of electrons of an atom can donate or accept to attain the stability of a complete valence shell. The elements with valency 1,2 and 3 are respectively called monovalent, divalent and trivalent element.
Example –
Valency of Sodium(Na) is 1.
Oxygen (O) is 2.
Nitrogen (N) is 3.

Question 11.
What is variable valency?
Answer:
Various elements like Iron, Copper etc. possesses more than one valency. These elements can form different compounds by changing their valencies when they combine with different number of atoms of the same element. These elements have variable valencies. For example, iron forms two compounds with chlorine, FeCl₂ (Ferrous Chloride) and FeCl₃ ( Ferric Chloride). The valency of Iron in the two compounds is 2 and 3 respectively.

Question 12.
What is a chemical equation? Define reactants and products.
Answer:
If we express the chemical reaction in brief by using the formulae of reactants and products, then it is called a chemical equation.
The elements or compounds that take part in the chemical reaction are called the reactants.
The elements or compounds that form as a result of the chemical reaction are called the products.

Question 13.
How many types of chemical reactions are there?
Answer:
There are four types of chemical reactions –

1. Combination reaction.
2. Dissociation reaction.
3. Displacement reaction.
4. Double displacement reaction.

Question 14.
What is combination reaction? Give an example.
Ans:
The chemical reaction in which two or more elements or compounds combine to form a single new compound is called a combination reaction.
For example :-
Water is produced by combination of oxygen and Hydrogen.

Question 15.
What is dissociation reaction? Give example.
Answer:
When a single compound is dissociated into more tharrone subtance by the influence of heat or electricity then such type of reaction is called dissociation reaction.
For example –
When Potassium Chlorate is heated, oxygen is liberated.

Question 16.
What is Displacement reaction? Give example.
Answer:
Such a reaction, where one element takes its place by replacing another element of the compound is called displacement or substitution reaction.
For example – Iron displaces Copper from Copper Sulphate solution

Question 17.
What is double displacement reaction? Give example.
Answer:
The chemical reaction in which two compounds exchange their radicals is called a double displacement reaction.
For example –
If dilute hydrochloric acid (HCl) is added to a solution of Silver Nitrate, a white insoluble solid (Silver Chloride) is formed.

Question 18.
What information we can get from symbol CO₂ ?
Answer:

1. Carbondioxide is a compound.
2. It is a molecule of Carbondioxide.
3. In a molecule of Carbondioxide there is one atom of carbon and two atoms of oxygen.
4. Molecular weight of carbondioxide is 44.

Detailed explanations in West Bengal Board Class 7 Science Book Solutions Chapter 8 Environment and Public Health offer valuable context and analysis.

WBBSE Class 7 Science Chapter 8 Question Answer – Environment and Public Health

(Page no. 256)

1. Which instrument do we use to measure temperature?
Answer:
thermometer.

2. Which kind of street lamps are now being used instead of electric bulbs and tube lights?
Answer:
Fluroscent bulb

3. A special kind of metal, liquid in nature is used to make thermometer and fluroscent bulb. Name it.
Answer:
mercury.

4. Now, let us find out the other sources from which mercury can enter the human body.
Answer:

• mirror
• light
• vegetables
• water.

(Page no. 257)

1. Now, let us find out the other sources through which Arsenic and Fluoride can enter our bodies.
Answer:

• water
• pesticide
• food crops.

2. Write the effects of X-ray on different organs of human below.
Answer:

• Oesophagous – Tendency of vomiting, Diarrhoea
• Lung-Breathing trouble.
• Bone marrow-Improper formation of blood cell. Haemorrhage, Cancer.

(Page no. 260)

Besides many other physical factors increase the risks and cause many diseases. Discuss with your friends or teacher and complete the chart.
Answer:

Physical factors causing disease in the professional field	Symptoms/disease
1. Electricity	Shock, Heart problem, Nerve disorder.
2. Heat	Burn, boils, injury
3. Cold	Frost bite, fever, cough and sneezing
4. Sound	Deafness, Headache.
5. Radioactive element	Anaemia, Cancer, skin disease.

B. 1. Compounds of which metal did ancient Egyptians used to colour their potteries? (Iron/ Copper/Zinc) Copper.
2. Which gas can cause death in closed mine? (Hydrogen/Oxygen Carbon monoxide) Carbon- mono-oxide.
3. Which chemicals are used in colouring cosmetic cotton and toilet articles? (water/ Sodium chloride/Synthtic organic dies) Synthetic organic dies.
4. Which metal or metallic compounds are used in wall paints, making toys or making batteries? (Iron, Sodium, Lead) Lead.
We came to know about many components of chemical environments from the above discussion.

As per chemical nature these are-

Chemical Nature	Name of the component
1. Gas	Carbon-di-oxide, Carbon monoxide, Sulphurdioxide.
2. Metal	Mercury, Flouride.
3. Synthetic compound              ‘	Organic dies, chemicals.

Now discuss with your friends/teachers/doctors what diseases may occur in being engaged in above mentioned professions.

• Diabetes
• High blood pressure
• Pain in neck
• Insomnia
• Sugar
• Arthritis.

(Page no. 262)

Try to write down the diseases on problem related to the following professions :
Answer:

Professions	Related diseases/problems
1. Those who pick up tea leaf	decay of fingertips
2. Those who are traffic police.	breathing problem, poor eyesight, restlessness.
3. Those who are carpenter.	breathing problem, muscle cramp
4. Those who carry goods	pain in neck, anaemia
5. Rickshaw-puller	Arthritis, muscle cramp
6. Those who cook in front of oven	ache in eye, breathing problem, diz ziness
7. Those who work in cotton factory	breathing problem, anaemia
8. Those who are hospital worker	dizziness, vomiting tendency
9. Those who are worker in mines	breathing problem, dizziness, wound in skin
10. Those who are worker in construction industries.	Arthritis, cancer, wound in skin, muscle cramp, brittle bone
11. Those who work in laboratories.	ache in eye, poor eye sight, vomiting tendency, less or more hunger
12. Those who works in different factories	deafness, restlessness, cancer, heat cramp
13. Those who work in Jute factories	faint, anaemia
14. Those who are hawker	heat cramp, varicose vein of legs, less or more hunger

(Page no. 273)

Which of the following picture will you choose to control your anger and why ?

Listening Music, Do exercise, singing, Reading Books, Playing, Face to Face talking, Dancing with Music, Watering in the garden, Meditation or Yoga.

Way out of controlling anger	Why did you choose this method
Reading books.	It gives pleasure and calms down our mind.
Meditation or Yoga.	relieves mental tension and increases concentration.
Dancing with Music.	It gives joy and relieves tension.
Playing.	Increases concentration, calms mind.
Watering in the garden.	It gives pleasure and increases love for nature

(Page no. 274)

Name of the disease	How it spreads
1. Common cold	1. By air
2. Dysentery	2. By water
3. Malaria	3. By mosquito
4. Plague	4. By rats
5. Rabies, Hydrophobia	5. By dogs.

(Page no. 275)

Can you tell me how diseases spread through air? Let us write how common cold spreads.

How does common cold spread?	What precautions should a person suffering from common cold take so that the disease does not spread?
1. By sneezing	1. We should use handkerchief while sneezing.
2. By spitting or coughing	2. We should not spit or cough in front of any person.
3. Talking with affected person	3. We should keep distance or cover our mouth while talking
4. By air	4. We should not move freely in pub­lic places.

(Page no. 277)

Now discuss with your friends. Try to find out who among you suffer from the same problems.

Cause behind the problem.	Nature of the problem	How did you get rid of the problem
I. Eating eggs	rashes in body, sneezing, vomitting	take medicine
2. Dust entering the nose.	burning sensation in eyes and nose sneezing, water comes out from nose.	use handkerchief
3. Eating Prawn.	red rashes, itching sensation	take medicine
4. Inhaling pollen of flower.	sneezing, burning sensation in nose.

Measures to prevent air-borne diseases :

• When ill, at the time of sneezing/ coughing cover your mouth and nose with a handkerchief.
• Do not spit here and there.
• Do not come in close contact with affected person.

(Page no. 278)

Fill up the following table after bearing about some other air borne diseases.

(Page no. 285)

Fill up the following table after barning about some water-borne disease.

(Page no. 288)

Try to write the name of some other disease which are spread by animals.

Name of the disease	The organism that spreads the disease
1. Malaria 2.  Dengue 3.  Typhoid 4.  Plague 5. Cholera 6.  Yellow Fever 7.  Rabies 8.  Filaria (Elephantiasis)	bite of female Anopheles mosquito bite of Aedes aegypti mosquito, rod-shaped bacteria Salmonella Typhi bite of rat fliesAedes mosquito biting of dogs and foxes small worm Wuchereria

Class 7 Science Chapter 8 Question Answer West Bengal Board – Environment and Public Health

Multiple Choice Questions & Answers : (1 mark for each question)

Question 1.
Which one of the following in water-borne disease?
i) Diabetes
ii) Cholera
iii) Allergy
iv) Scurvy
Answer:
ii) Cholera.

Question 2.
Which of the following disease has been eradicated?
i) Small Pox
ii) Plague
iii) Polomyelities
iv) Kala-zar
Answer
i) Small-Pox

Question 3.
Well known effective drug for Malaria is ………….
i) Penicilin
ii) Paracitamol
iii) Quinine
iv) Cough syrup
Answer:
iii) Quinine.

Question 4.
A viral disease is …………..
i) Cancer
ii) Leukaemia
iii) Typhoid
iv) Yellow fever
Answer:
iv) Yellow fever

Question 5.
Dehydration results from …………..
i) Pneumonia
ii) Measles
iii) Rabies
iv) Cholera
Answer:
iv) Cholera.

Question 6.
Name of the British army doctor who proved that Malaria is a mosquito-borne disease is ………
i) Louis Pasteur
ii) Ronald Ross
iii) Dr. Edward Jenner
iv) Joseph Lister
Answer:
ii) Ronald Ross

Question 7.
Aedes mosquito spreads ………
i) Dengue
ii) Typhoid
iii) Malaria
iv) Kala-zar
Answer:
i) Dengue

Question 8.
Which is a beneficial fungi?
i) Neurospora
ii) Claviceps
iii) Penicuilium
iv) Rhizopus
Answer:
iii) Penicillium.

Question 9.
A harmful chemical added to chowmin and chilly chicken to impart a meaty flavour is ……………….
i) Clove
ii) Turmeric
iii) Ajinomoto
iv) Chilly
Answer:
iii) Ajinomota

Question 10.
Which seed is mixed with mustard seed—
i) Poppy seed
ii) Rapeseed
iii) Gramseed
iv) Argemone seed
Answer:
iv) Argemone seed.

Fill in the blanks : (1 mark for each question)

1. The…………. look after our mental health.
Answer:
psychologists.

2. The menance of …………. has been fully eradicated from the world by vaccination alone by the year 1977.
Answer:
small pox.

3. Tuberculosis is a …………. disease.
Answer:
communicable

4. The substances that cause allergy in our body are termed as ………….
Answer:
allergen.

5. …………. spreads from contaminated water.
Answer:
cholera.

6. Diseases which spread through water are termed as ………….
Answer:
water-borne diseases.

7. …………. is one type of malarial parasite.
Answer:
Plasmodium Vivax.

8. Mosquito is the …………. host and other vertebrate animals are the host.
Answer:
primary or definitive, secondary or intermediate.

9. …………. spread diseases like Typhoid and Diarrhoea.
Answer:
House fly.

10. Usually the …………. grow on food items rich in Carbohydrates.
Answer:
fungi.

State whether True or False : (1 mark for each question)

1. Powdered khesari dal is mixed with besan because khesari dal is very cheap.
Answer:
true

2. Lathyrism has been observed in America.
Answer:
false

3. Argemone seeds are darker than mustard seeds.
Answer:
true

4. Coloured sweets and icecreams may contain colourants that can cause cancer.
Answer:
true

5. Various dyes used during Holi can cause problems of heart.
Answer:
false

6. Sometimes immediately after eating food items like prawn and brinjal uneasiness sets in the body.
Answer:
true

7. Poultry products, raw vegetables unpasteurized milk often contain harmful mi¬crobes.
Answer:
true

8. Usually the fungi grow on food items rich in fats.
Answer:
false

9. The mosquito is a mechanical vector.
Answer:
false

10. Spoilage of various types of food is due to the microbial degradation by various microorganisms.
Answer:
true

11. House flies spread Kala-azar.
Answer:
false

12. Legs of sand flies are long and thin.
Answer:
true

Match the column A with column B

Column A	Column B
a) Lathyrism has been observed	i) attacks the poultry birds
b) Some safe colours are now being	ii) may be present in food
c) A type of influenza virus	iii) made from flowers
d) Yeast is required for	iv) spread Malaria
e) Some very dangerous types of bacteria	v) make no sound while flying
f) Aedes mosquitoes	vi) in Ethiopia, Bangladesh and India
g) Anopheles mosquitoes	vii) spread dangue
h) Culex mosquitoes	viii) making bread

Answer:
a) Lathyrism has been observed in Ethiopia, Bangladesh and India.
b) Some safe colours are now being made from flowers.
c) A type of influenza virus attacks the poultry birds.
d) Yeast is required for making bread.
e) Some very dangerous types of bacteria may be present in food.
f) Aedes mosquitoes spread dangue.
g) Anopheles mosquitoes spread Malaria.
h) Culex mosquitoes make no sound while flying.

Very Short Questions & Answers : (1 mark for each question)

Question 1.
Name some chemical which can cause harm if they enter our body.
Answer:
Arsenic and Fluoride.

Question 2.
Define the term health.
Answer:
Health means physical, mental and social healthiness, it does not only mean fitness of body.

Question 3.
Mention some steps of prevention of disease.
Answer:
Vaccination, to add nutritious ingredients from outside (Iodine, iron, Vitamin)

Question 4.
Name some diseases which spread through air.
Answer:
Common cold, Cough, Flu, Chicken Pox, Scarlet fever, Diptheria etc.

Question 5.
Name some water-borne diseases.
Answer:
Cholera, Diarrhoea, Jaundice, Typhoid, Tuberculosis and Dysentery.

Question 6.
Name the organs mosquitoes use to drink blood.
Answer:
Labium, Mandible, Maxilla, Hypopharynx and Labrum.

Question 7.
What kind of mosquitoes spread Malaria?
Answer:
Anopheles mosquitoes spread Malaria.

Question 8.
What kind of mosquitoes spread Filaria?
Answer:
Culex mosquitoes spread Filaria.

Question 9.
What kind of mosquitoes spread Dengue?
Answer:
Aedes mosquitoes spread Dengue.

Question 10.
Mention an identifying feature of Asdes mosquitoes.
Answer:
While taking rest they sit almost paralleliy to the ground.

Question 11.
Mention an identifying feature of Anopheles mosquitoes.
Answer:
While taking rest they sit making an acute angle with the surface.

Question 12.
Mention an identifying feature of Culex mosquitoes.
Answer:
While taking rest they sit paralleliy as the surface.

Question 13.
Mention a symptom of Polio.
Answer:
Unnatural fatigue in the muscles of hands and legs.

Question 14.
What is the name of pathogen of Tuberculosis?
Answer:
Bacteria is the pathogen of Tuberculosis.

Question 15.
Write a measure to prevent airborn diseases.
Answer:
When ill, at the time of sneezing/coughing one must cover his mouth and nose with a handkerchief.

Question 16.
What is the name of pathogen of common cold.
Answer:
Virus is the pathogen of common cold.

Question 17.
When Cholera appeared in form of epidemic in bengal?
Answer:
In the year 1817 Cholera appeared in form of epidemic in bengal.

Question 18.
In what type of food items bacteria grow?
Answer:
Generally Bacteria grow in food items rich in protein (e.g. meat, egg, fish, dairy products)

Question 19.
In what type of food items fungi grow?
Answer:
Usually the fungi grow on food items rich in Carbohydrate.

Question 20.
Name some Bacterial Pathogen caused disease.
Answer:
Salmonellosis. Campylobacteriosis, Food-borne toxicity, Botlism.

B Short Questions & Answers : (2 marks for each question)

Question 1.
How are fungi beneficial?
Answer:
Fungi is used to produce food like bread, cheese and alcoholic beverages. Some antibiotics are produced from fungi, penicilium and yeast is required for making bread.

Question 2.
Why House fly is called a Mechanical vector and mosquito a Biological Vector?
Answer:
House fly only does the work of carrying the germ, so it is called Mechanical Vector. On the other hand the mosquitoes allow the germ to breed inside their body, so the mosquito is a Biological Vector.

Question 3.
What are Parasites?
Answer:
Some worms infest various organs of animals. These worms are parasites. If we take raw or under cooked meat of such animals, the parasites enter our bodies causing many diseases.

Question 4.
What is Bird-flu? How it effects other birds and human beings?
Answer:
Often a type of influenza virus (H5N1) attacks the poultry birds, this is called Bird-flu. The saliva catarrhal discharge or excreta of affected birds can infect other birds too. If human beings come in contact with skin, excreta or blood of virus-infected chicken, they can catch the diseases.

Question 5.
How microbial contamination of food occurs?
Answer:
Poultry products (egg, milk), raw vegetables unpasteurized milk often contain harmful microbes. If these food items are not properly processed or if they are taken raw, various types of infections may arise.

Question 6.
What is Allergy?
Answer:
Our immune system sometimes reacts to different proteins or other substances present in food. Allergy is basically the response generated by our immune system towards foreign proteins. This may cause itching sensation, rashes on skin and uneasiness in the body.

Question 7.
what can happen if food items with harmful additives is taken for a long time?
Answer:
Prolonged use of food items containing such harmful additives can lead to serious problems of the degestive and nervous system. It can also cause kidney diseases and may even cause cancer.

Question 8.
What is radioactive substances?
Answer:
Some invisible rays are emited continuously from elements like uranium and plutonium and other compounds. These are called radioactive substances.

Long Questions & Answers : (3 marks for each question)

Question 1.
Mention some causes of mental problem.
Answer:

• Disorder by birth: malnutrition of foetus, various infection after birth prevents the growth of mind and intelligence of the child.
• Mental pressure: various violent activities, unexpected incidents some times causes mental pressure beyond tolrance.
• Many family problems.
• Conflict and being unable to take decision.
• Addiction.

Question 2.
What is the proboscis? Did it help in male mosquito in sucking blood? How it is used by the mosquito to spread diseases?
Answer:
Various mouth parts of a mosquito get transformed into a proboscis for their special food habit. The mosquito has a long tubes like proboscis. In case of female mosquitoes the proboscis is slender and pointed just like an injection needle. But the proboscis in a male mosquito is blunt, so they can suck only different plant juice like necter, juice of fruits etc.

At the time of sucking blood a female mosquito infuses to saliva into the body and that animal through proboscis. They do so for preventing the blood from getting coagulated while sucking. Through this saliva the germs from the blood of a female mosquito enter into the body of that animal.

Question 3.
Which mosquito spread Malaria? Write down its identifying features.
Answer:
Female Anopheles spread Maleria. Its identifying features are-

• Black spot on the wings.
• At the time of taking rest they sit making an acute angle with the surface
• Make sound while flying.
• Come out in the evening.
• Lay eggs in clean water.

Question 4.
Name the diseases spread by Sand Fly. How can you identify it?
Answer:
Sand Fly spreads Kala-zar and Sand Fly fever.

• Sand flies are smaller than mosquitoes in size.
• Body is very hairy.
• Legs are long and thin.
• Come out after dark.

Question 5.
Describe the identifying features of Culex Mosquito. Name the diseases Culex can spread ?
Answer:
Identifying features of Culex mosquitoes are

• No spot on the wings.
• Sit parallelly as the surface while taking rest.
• Make no sound while flying.
• Come out at night.
• Lay eggs in dirty water. Culex mostquitoes spread Filaria and Encephalitis.

Question 6.
Name the diseases Aedes mosquitoes spread. How can we identify them?
Answer:
Aedes mosquitoes spread Dengue and Chickungunia diseases. Each identifying features are —

• White and Black stripes on the abdomen and legs.
• While taking rest sit almost parallely to the ground.
• Make no sound while flying.
• They come out in day time.
• Lay eggs in clean water.

Question 7.
What are the identifying features of House Fly? Name the diseases they can spread.
Answer:
A House Fly has ……..

• Grey-coloured thorax.
• 4 long black stripes on the back.
• Whole body is covered with hair.
• They come out during day time and remain inactive at night. House Flies spread Typhoid and Diarrhoea.

Question 8.
Onchocerciasis disease is spread by a fly, name it and describe its features.
Answer:
Black Fly spreads on Onchocerciasis

• Black Fly is black in colour.
• Proboscis is small in size and like a toothed dagger.
• Body is stout
• Come out during day time in groups and are very active just before down and dusk.

Question 9.
How fly spreads diseases?
Answer:
The fly spreads diseases in three different manners.
(i) Whenever they sit on stool, urine, pus, spittle etc. then minute particles of those things get stuck to their legs and antennae. When this fly sits on food items, germs are mixed with those food stuff and infection occurs.

(ii) The fly can not take solid food. So they vomit on solid food. As a result, parts of the solid food gets liquified and the fly takes the food with the help of the proboscis. With that vomit the germs from the body of the fly get mixed with our food items and infection occurs.

(iii) House flies excrete throughout the whole day at the interval of five minutes wherever
they sit. Many germs are present in the stool of the fly. When they defecate on our food, these germs get mixed with our food.

Question 10.
Tell the difference in the ways of transmission of diseases by the flies and the mosquitoes
Answer:

Question 11.
Describe some resources to control mosquito.
Answer:

• Water in reservoirs, buckets, flower vases should be changed every 2-3 days.
• Fishes like (Guppy, Panchax, Shol, Lata, Gambusia etc.) should be allowed to grow in stagnants waters because they eat the larvae of mosquitoes.
• Kerosene, diesel, bleaching powder should be spiaiged in the drains.
• Mosquito killer spray or liquid water should be used inside house to keep it free from mosquitoes.

Question 12.
Why food stuff gets spoiled?
Answer:
Spoilage of various types of food is due to the microbial degradation of food by various micro organisms. These micro-organisms are generally bacteria and fungi. When the microbes present in a food grow, they degrade the food with their enzymes and absorb the simple compounds thus obtained into their cells.

Question 13.
Name some Bacteria which are beneficial.
Answer:
Lactobacillus Bacteria help to-make curd. We obtain many life saving drugs from several species of streptomyces Bacteria. Some special Bacteria residing in the stomach of cattle help them in digesting cellulose. Some intestinal Bacteria help human beings by producing the much-needed vitamin Bp.

Question 14.
What is pasteurization?
Answer:
In simple words, pasteurization is the process of destroying the pathogenic microbes along with to their spores in food, especially liquid food (mild and dairy products, fruit juice etc.) This method of making foods and beverage free from microbes was discovered by the french Louis Pasteur, so to honour him the method is named as Pasteurization.

Question 15.
What are the common symptoms of allergy from food?
Answer:

• Rashes on skin.
• Itching sensation all over the body.
• Swelling of lips, throat and tongue
• Uneasiness in throat respiratory problems.
• Redness in eye and face,
• Vomiting
• Abdominal cramp
• Diarrhoea.

Question 16.
When a food can be said to be adultered?
Answer:

• When something is added to food that lowers its nutritional value.
• When some cheap additive is mixed with food instead of some necessary ingredients.
• When some harmful additive is added to the food to make the food look more attractive and to bring desirable flavour.

Question 17.
What is ‘dropsy’? How dropsy affects us?
Answer:
Argemone seeds closely resemble mustard seeds are cheaper than mustard. The oil extracted from argemone seeds is deliberately mixed with mustard oil. Long term use of such idulterated mustard oil. cause a disease called ‘dropsy’. Dropsy severely damages skin and organs like liver, lungs, kidney and heart. It can even cause failure of heart and the lungs, leading to death.

Question 18.
What is Lathyrism?
Answer:
Often Khesari daal which is very cheap (seeds of Lalhyrus Sativus) mixed with Arhar daal. Continued intake of substantial amount of Khesari daal for 2-3 months can cause progressive spastic paralysis. This is Lathyrism.

Question 19.
How fungi can be beneficial?
Answer:
We take the help of fungi to produce food items like bread, cheese and alcoholic beverages. The affinity of fungi for carbohydrate-rich food help the fungi in making those food items and beverages. For example, some antibiotics are produced from the fungus penicillium yeast is required for making bread.

Detailed explanations in West Bengal Board Class 7 Science Book Solutions Chapter 2 Time and Motion offer valuable context and analysis.

WBBSE Class 7 Science Chapter 2 Question Answer – Time and Motion

(Page no. 70)

Select the correct option from below and fill in the blanks:
1. Rectilinear motion.
2. Motion in a circular path.
3. Rotational motion.
4. Combination of Rotational and Rectilinear motion.
5. Curvilinear motion
Answer:

Examples of different types motion	Name of the motion
1. The motion of the pencil tip while drawing a straight line with a ruler.	Rectilinear motion
2. Motion of the tips of clock-hand	Motion in a circular path.
3. Motion of a stone which is thrown away from the roof.	Curvilinear motion.
4. Motion of merry-go-round.	Motion in a circular path.
5. Motion of a spinning top at a fixed point.	Combination of rotational motion and rectilinear motion.
6. Motion of a clock’s pendulum.	Rectilinear motion.
7. Motion of a car along a straight road.	Rectilinear motion.
8. Motion of a cycle along a straight line.	Rectilinear motion.
9. Motion of a screw driver.	Curvilinear motion.
10. Motion of an electric fan’s blade.	Rotational motion.

Class 7 Science Chapter 2 Question Answer West Bengal Board – Time and Motion

Multiple Choice Questions & Answers : (1 mark for each question)

Question 1.
The rate of change of displacement with time is called-
i) speed
ii) retardation
iii) velocity
Answer:
iii) velocity

Question 2.
Distance travelled by a moving object-
i) can be zero
ii) cannot be zero
Answer:
ii) cannot be zero

Question 3
If the velocity of the body decreases with time, the motion is said to be
i) acceleration
ii) retardation
iii) displacement
is Answer:
ii) retardation

Question 4.
In SI system unit of retardation is-
i) MS²
ii) MS^-1
iii) MS^-2
Answer:
iii) MS^-2

Question 5.
The state of motion and rest of an object is-
i) absulute
ii) relative
Answer:
ii) relative

Question 6.
The average velocity of an object-
i) could be zero
ii) could not be zero
Answer:
ii) could not be zero

Question 7.
A rotating fan take sometime to stop when it is suitched off due to
i) interia of motion
ii) momentum
iii) air current
Answer:
i) interia of motion

Question 8.
The distance travelled by the body in a unit time interval is called
i) velocity
ii) speed
iii) acceleration
Answer:
ii) speed

Question 9.
If force is applied from outside on a moving body then its momentum
i) decrease
ii) increase
iii) does not change
Answer:
ii) increase

Question 10.
If a rubber ball is thrown on a wall it comes back, this can be explained by Newton’s-
i) First law
ii) Second law
iii) Third law
Answer:
iii) Third law

Question 11.
The action and the reaction both act on-
i) two different objects
ii) same object
Answer:
i) two different objects

Question 12.
We come to know about the rate of change of momentum when force is applied, from the Newton’s-
i) first law
ii) second law
iii) third law
Answer:
ii) second law

Question 13.
We know about definition of force from Newion’s-
i) first law
ii) second law
iii) third law
Answer:
i) first law

Question 14.
In CGS unit of force is-
i) Newton
ii) gram-weight
iii) dyne
Answer:
iii) dyne

Question 15.
The property of a body to remain at rest forever is called-
i) inertia of motion
ii) inertia of rest
iii) momentum
Answer:
ii) inertia of rest

Question 16.
Th property of inertia of a body is-
i) fundaniental
ii) not fundamental
Answer:
i) fundamental

Fill in the blanks : (1 mark for each question)

1. The tendency of a body to keep itself at rest for ever is known as _______ of rest.
Answer:
inertia.

2. Speed is a _______ quantity.
Answer:
scalar.

3. Two vector quantities with same units are _____ and ________.
Answer:
acceleration, retardation.

4. ____ is the rate of change of velocity with time.
Answer:
Acceleration.

5. Dimensional formula of retardation ______.
Answer:
LT^-2

6. To change the state of inertia we apply ______.
Answer:
force.

7. Dimensional formula of velocity _____.
Answer:
LT^-1

8. A body which changes is position with time is called a ____ object.
Answer:
moving.

9. Force = mass × ________.
Answer:
acceleration.

10. 1 Kgf = ______.
Answer:
9.8 N (Newton).

11. One newton is the force which when acts on a body of mass 1 kg produces an acceleration of _____.
Answer:
1 m/ sec^-2

12. Dimensional formula of momentum _______.
Answer:
MLT^-1

13. In SI system the gravitational unit of force is ______.
Answer:
Newton.

14. 1 Newton = 1 kg × _________.
Answer:
1 m/sec²

15. In SI system the unit of momentum is _______.
Answer:
Kilogram-meter/second.

16. The action and the reaction both act on ______ bodies.
Answer:
two different.

17. The rate of change of momentum is proportional to _______.
Answer:
force.

18. Momentum is a _____ quantity.
Answer:
Vector.

State whether True or False : (1 mark for each question)

1. If a body has zero speed it can have acceleration.
2. Acceleration is a scalar quantity.
3. Velocity is a vector quantity but speed is not.
4. In speed magnitude and direction both are to be mentioned.
5. A body may have uniform speed but it may not have uniform velocity.
6. The rate of increasing velocity is called uniform velocity.
7. Motion of the tips of clock-hand is called rotation.
8. When a moving object change its place it is called displacement.
9. If an object have zero displacement, it can have distance.
10. To express velocity we have to mention both its derection and magnitude.
11. We got defination of force from Newton’s second law.
12. In SI system unit of force is Newton.
13. Measure of force is known from Newton’s third law.
14. Action and reaction cannot suppress each other.
15. If a moving bus suddenly stops the passengers moves in front ward direction.
16. If 1 Newton force works on 1 gm mass then 1cm / sce² acceleration is produced the body.
17. Reaction remains as long as action persists.
18. If a body has less mass then it has less accleration.
19. If a vehicle suddenly starts to move it’s pas: engers lean backward direction.
20. Force applied = mass × retardation.
Answer:
1. true
2. false
3. true
4. false
5. true
6. false
7. true
8. false
9. true
10. true
11. false
12. true
13. false
14. true
15. true
16. false
17. true
18. false
19. true
20. false

Match the column A with column B.

Column A	Column B
a) Capacity of doing work	i) more work is done
b) Increase in the rate of respiration	ii) was the president of Royal Society
c) Increase in the rate of heartbeat	iii) to do work
d) When we spend more energy	iv) is called energy
e) Energy’ is the ability	v) is Newton
f) To every action there is an	vi) we apply force
g) Sir Issac Newton	vii) generates more heat
h) In SI system the unit of force	viii) increase in the rate of respiration
i) To change the state of inertia	ix) is Dyne
j) In CGS system the unit of force	x) equal and opposite reaction

Answer:
a) Capacity of doing work is called energy.
b) Increase in the rate of respiration generates more heat.
c) Increase in the rate of heartbeat increase in the rate of respiration.
d) When we spend more energy more work is done.
e) Energy is the ability to do work.
f) To every action there is an equal and opposite reaction.
g) Sir Issac Newton was the president of Royal Society.
h) In SI system the unit of force is Newton.
i) To change the state of inertia we apply force.
j) In CGS system the unit of force is Dyne.

Short Questions & Answers : (1,2 marks for each question)

Question 1.
How many types of motion are there?
Answer:
There are two types of motion.
i) Rotation and ii) Revolution.

Question 2.
What is Revolution?
Answer:
When a moving object travels in an orbit while rotating on its own axis then the motion of that object is called revolution.

Question 3.
What type of motion is seen in a moving car?
Answer:
Moving car has mixed motion.

Question 4.
Why displacement is a vector quantiny?
Answer:
Displacement has both magnitude and direction. So it is a vector quantity.

Question 5.
What type of motion has a moving electric fan?
Answer:
It has rotational motion.

Question 6.
What is the unit of speed in SI system?
Answer:
In SI system the unit of speed in meter/second.

Question 7.
Is speed vector or scalar quantity?
Answer:
Speed is vector quantity.

Question 8.
Which physical quantity has unit as meter/second² ?
Answer:
In SI system acceleration has unit as meter/second².

Question 9.
What is the unit of velocity? Is it a scalar or vector quantity?
Answer:
In CGS system unit of velocity in centimeter/sec. and in SI system unit of velocity is meter/second. Velocity is a vector quantity.

Question 10.
A body after moving in a circular part comes back to its starting point, what is its displacement?
Answer:
If a body after travelling in a circular part comes back to its starting point, the displacement is zero.

Question 11.
What we come to know from Newton’s Fast law?
Answer:
From Newton’s fast law, we come to know about- (i) Inertia and (ii) force.

Question 12.
From which law of Newton we come to know about force?
Answer:
We come to know about force from Newton’s fast law.

Question 13.
What is the unit of force in CGS system?
Answer:
In CGS system the unit of force is Dyne.

Question 14.
What is the unit of force in SI system?
Answer:
In SI system the unit of force is Newton.

Question 15.
One Newton = ? Dyne.
Answer:
One Newton = 10⁵ Dyne.

Question 16.
Name the types of Inertia.
Answer:
Inertia are of two types – i) Inertia of rest and ii) Inertia of motion.

Question 17.
Is force vector quantity or scalar quantity?
Answer:
Force is vector quantity.

Question 18.
What is’ the unit of momentum in SI system?
Answer:
In SI system the unit of momentum is Kilogram-meter/second.

Question 19.
1 gm. force = how much Dyne?
Answer:
lgf = 980 dyne.

Question 20.
What is the unit of work in SI system?
Answer:
A unit of work in SI system is Joule.

Question 21.
What is energy? How we get energy?
Answer:
The energy of a body is its capacity to do work.
We get energy from food. We get something from food which gives us ability for doing work.

Question 22.
How can we feel that energy is being spent inside our body?
Answer:
Fatigue, increase in the rate of heart beat, increase in the rate of respiration, increase in the temperature of the body etc help us to understand that energy is being spent inside our body.

Question 23.
Sometimes you may have noticed that birds glide some disatance without moving its wings. Why does the birdmove in this manner?
Answer:
A flying bird is a moving object. It tries to remain in uniform motion when there is no force on it. So, without moving its wings it goes farther distance because of inertia of motion.

Question 24.
What is inertia?
Answer:
The tendency of a body of remaining at rest or in uniform motion is known as ‘inertia’ of the body.

Question 25.
What is ‘inertia of rest’ and ‘inertia of motion’?
Answer:
The tendency of a body to keep itself at rest forever is known as ‘inertia of rest’.
The tendency of remaining in uniform motion of the body is called as ‘inertia of motion’.

Question 26.
What is force?
Answer:
What we apply to change the state of inertia is called as force.

Question 27.
Explain Newton’s Third law of motion?
Answer:
Newton’s third law of motion is – To every action, there is an equal and opposite reaction.

Question 28.
When we can say a work is done?
Answer:
Work is said to be done only when body move (i.e. there is a displacement of the body).

Long Questions & Answers : (3 marks for each question)

Question 1.
Explain the concept of Newtons first law of motion.
Answer:
If there is no external force acting on a body, then-
i) The body at rest will remain at rest forever,
ii) The moving body will go with constant speed in the same direction of its motion.

Question 2.
Explain Newton’s second law of motion.
Answer:
Newton’s second law of motion states that-
i) If we apply more force on a body of fixed mass, its change of velocity will be more in one second. If we double the force, the acceleration of the body also doubles. That is to say there is a linear relation between force and acceleration.
ii) The direction to which the froce acts, the direction of acceleration is also the same. That is the velocity of the body increases along the direction of applied force.

Question 3.
Write down the equation for the magnitude of applied force, according to Newton’s second law of motion.
Answer:
Applied force = mas of the body × change in velocity in 1 second. = mass of the body × acceleration produced (change in velocity in one second = acceleration)

F = m × a[F = force, m = mass, a = acceleration]
The unit of force in SI system is 1 Newton.
1 Newton =1 kg × 1 m / sec²

Question 4.
Who was Sir Issac Newton?
Answer:
Sir Issac Newton was an English physicist, mathematician and astronomer. He proposed the Three Laws of Motion, Spectrum of Sunlight. Universal Law of Gravitation, Binomial Theo rem. Differential calculus etc. On December, 1642. Newton was born in a peasant family of Willsthrope in England. He got BA degree from Trinity college of Cambridge University in 1669 at the age of 27 . He died in 1727.

Question 5.
Why was Sir Issac Newton famous?
Answer:
Sir Issac Newton invented laws of Motion, Spectrum of sunlight, Binomial theorem, Differential Calculus etc expanded a new era of science and mathematics. He was the president of Royal society from 1672 for next 25 years. He wrote the famous book “Principia Mathematica”.

Question 6.
When a bus suddenly starts moving from rest, the passengers in the bus leans in backward direction, explain why?
Answer:
When the bus is not in motion, the passenger with the bus are at rest. When the bus suddenly starts moving the situation change. The foot of the passengers starts moving with the bus. but the upper part of the body tries to remain at rest. So the legs move away in forward direction. the body leans in reverse direction.

Question 7.
Explain how we can find out the quantity of work done in physics.
Answer:
Word done = ( applied force) × displacement in the direction of the force) W = F × d[W = Work, F = Force, d = displacement]
If the displacement of the body is 1m in the direction of a force of 1N. Then the work done is I Joule or 1J.
& W = F × d
1J = 1N × 1M = 1N.m

Detailed explanations in West Bengal Board Class 7 Science Book Solutions Chapter 1.5 Use of Environment Friendly Energy offer valuable context and analysis.

WBBSE Class 7 Science Chapter 1.5 Question Answer – Use of Environment Friendly Energy

(Page no. 63)

Write some other uses of thermal energy in the gaps given below :
Answer:

(Page no. 64)

Mention some of other uses of electric energy to the gaps given above. Similarly fill in the gaps given below about the uses of fossil fuels known to you.
Answer:

(Page no. 65)

What are directly related to population explotion? (Fill up the blanks) :
Answer:

(Page no. 67)

Foreign countiies are using solar energy since long time back.
We have also started using solar energy extensively in our state.
Fill in the blanks if you have noticed it.

Where is solar energy used?
Answer:
Solar energy is used in homes and on streets.

What purpose is it used for?
Answer:
Solar cooker is used to prepare food and solar light is used on streets.

(Page no. 68)

Write the names of the places in our state or other states where you have seen such wind mills.
Answer:
Rajasthan and Tamil Nadu.

(Page no. 68)

Write the uses of bio-gas.
Answer:
1. For cooking
2. To lit bulbs.

Discuss the potentials of degradable organic municipal waste or weeds like water hyacinth. How can we use them?
Answer:
Energy can be obtained from wastes. It can be used to lit bulb, run fans and cook food.

Class 7 Science Chapter 1.5 Question Answer West Bengal Board –Use of Environment Friendly Energy

Fill in the blanks : (1 mark for each question)

1. We need _______ to do any kind of work.
Answer:
energy.

2. To run power tiller ______ is used.
Answer:
diesel.

3. ______ is used as Jet fuel.
Answer:
Kerosene.

4. ______ is used in motor cycle.
Answer:
Petrol.

5. ______ is used to run fan and use light.
Answer:
electrical energy.

6. ______ fuels are formed from the remains of plants and animals over a span of millions of years.
Answer:
Fossil.

7. The large portion of electrical energy is produced in our country by burning ______.
Answer:
coal.

8. _______ of years are required for the formation of energy sources like coal or petroleum under the soil of earth.
Answer:
Millions and millions.

9. Demands for the conventional forms of energy are increasing day by day due to ______.
Answer:
Population explosion.

10. Petroleum is obtained by ______ holes in the Earth crust, where the oil is found.
Answer:
drilling.

11. Due to excessive use of fossil fuel ______ is increasing.
Answer:
pollution.

12. ______ is an environment friendly energy.
Answer:
Solar energy.

13. Coal, petroleum and natural gas are _____ fuels.
Answer:
fossil

14. Solar energy can be used to generate electricity in _______ cells.
Answer:
solar.

State whether True or False: (1 mark for each question)

1. Coal and petroleum is formed from the remains of plants and animals buried under the earth.
2. Animals depend upon sun indirectly.
3. Drilling of petroleum first started in Asia continent.
4. Solar energy is being used in our country since long time back.
5. Solar panel didn’t cause any harm to our environment.
6. Solar panel lasts for 100 years.
7. There are large wind mills in Bakkhali in our state.
8. Natural gas is obtained from organic waste.
9. Remains of plants and animals are called fossils.
10. Bio-gas is produced from the various organic waste.
Answer:
1. true
2. true
3. true
4. false
5. true
6. false
7. true
8. false
9. false
10. true

Short Questions & Answers : (1, 2 marks for each question)

Question 1.
What are the uses of fossil fuels?
Answer:
Fossil fuels are used to – a) run generator. b) run power tiller. c) for running launch, aeroplane.

Question 2.
What are directly related to population explosion?
Answer:
With the growth of population – a) production of more food, b) Construction of more accomodation, c) increase of transport and d) establishment of more factories are necessary.

Question 3.
In early days how people used to go from one place to another?
Answer:
In early days people used bullock cart, horse, ass, elephant, stagecoach, boat etc or walked on foot to go from one place to another.

Question 4.
Nowadays how people travel from one place to another?
Answer:
Nowadays people use train, tram, bus, aeroplane, motorcycle, ship, launch etc to travel from one place to another.

Question 5.
What are environment-friendly forms of energies?
Answer:
Conventional forms of energies are exhausting day by day, they have also detrimental effects on our environment. Hence, we have to explore the posibilities of some new sources of energy. These energies would have less harmful effect on us. These are environment friendly forms of energies. Some such energies are – solar energy, wind energy, energy from biomass.

Question 6.
How solar energy is produced?
Answer:
The solar cell generates electricity during the day-time using the sunlight directly. The energy thus generated, is being accumulated in the batteries connected with solar pannels. It has got its use at night or during dimlight of day.

Question 7.
What are the various uses of solar energy?
Answer:
The various uses of solar energy are solar light, solar cap, solar cooker, solar bike, solar water-heater, solar signal, solar mobile charger

Question 8.
What are the advantages of using wind energy?
Answer:
The advantages are –
i) Their is no shortage of air flow.
ii) Once installed, the wind mills serve for a long time.
iii) The wind mills can be used as local generators for areas where installation of long transmission cable is not possible.

Question 9.
How energy from Bio-mass is produced?
Answer:
The excreta of animals the various organic wastes and different materials of plant and animal origin can be gathered in a large ditch. After anacrobic digestion, it produces bio-gas which can be used for different purposes.

Question 10.
Name some other eco-friendly sources of energy?
Answer:
Some other eco-friendly sources of energy are Tidal energy, Geo-thermal energy etc.

Long Questions & Answers : (3 marks for each question)

Question 1.
Mention some of the uses of heat energy.
Answer:
Heat energy is used –
a) for cooking.
b) electricity generation.
c) sterilising of knife, scissors before operation.
d) making bricks.
e) driving the steam engine.
f) burning of clay made things.
g) in smithy to make different kinds of tools.

Question 2.
Write down some uses of electrical energy.
Answer:
Electrical energy is used –
a) to operate the machine in industry.
b) for using computer.
c) for playing loudspeaker.
d) for running rail, tram.
e) to operate washing machine.
f) charging of mobile phone.
g) X-ray.

Question 3.
Is the source of underground fossil fuels in exhaustible?
Answer:
Yes, the source of under guound fossil is exhaustible. It took many millions and millons of years for the formation of the energy sources like coal or petroleum under the soil of earth. We are spending the resources in very short time comparable to the time of their formation. In this way a day will come when all the sources of coal or minerals would be exhausted.

Question 4.
Discuss the ways how the use of energy could be done as minimum as possible?
Answer:
a) The over use and wastages of energy have to be scaled down.
b) The life of coal and petroleum can be lengthened by producing less-polluting fuel in an appropriate way.
c) The gases emitted from the bed of rocks underneath or from the crevices of the hills, are generally wasted, we have to make use of such gases.
d) Instead of pumping out underground water for irrigation or drinking purposes, we can use the surface water from rivers etc.
e) If possible use of non-machanised boat for transportation or use of bicycles would be encouraged, it will save fossil-fuel.
f) Unnecessary use of energy in various types of amusements is to be curtailed down.
g) We have to ensure the awareness of everyone about the use of non-conventional sources of energy.