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)
What is happening in the pictures given above? Write down the reasons behind them.
Storm, Oceanic high tide, melting of snow cap in polar regions, flood, landslides. These occur due to increasing environmental pollution.
Now write the difference between Weather and 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)
What are the important factors on which weather and climate depend?
- Temperature of atmosphere.
- Humidity of atmosphere
- Movement of wind.
- Ocean current
Try to answer the following question:
1. When do buds appear in a mango tree?
In Spring season.
2. When do migratory birds visit our country from abroad?
During winter season.
3. When do the Husa fishes lay eggs?
In Rainy season.
4. When does Palash bloom?
In Spring season.
5. Write the name of some natural phenomena which occur in a definite time of the year.
- 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.
7. Do you know the name of any other season apart from Summer, Monsoon, Autumn and Winter?
8. Does Monsoon arrive at a definite time in every year?
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?
For three months.
What can happen if seasons stay for a longer or shorter period of time? Fill up the table below :
|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)
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 –
Midnapore, it is very hot in the month of May, monsoon comes here in June-July months, winter seasons are December and January.
What are the changes that you have experienced in the climatic conditions (temperature, rainfall etc.) in comparison with your childhood?
- 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.
What are the differences of present day climate with that of 20 years earlier?
- 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
What can be the reasons behind these changes?
- 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.
Do you know about any physical problem that arises due to these changes?
- Indigestion and other diseases regarding stomach.
- Skin problem.
- Cancer in various parts of body.
- Asthma and rise in blood pressure.
Trace out different problems (other than physical problems) of your locality due to climatic changes.
- 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.
What can be done so that the climatic change do not cause major disruptions?
- 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?
Pollution of environment.
(ii) Where does the emitted gases from various sources go?
In the atmosphere.
(Page no. 233)
Find out different news on global warming and write them down briefly.
|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.|
|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)
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.
|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)
Reasons for loss of bio-diversity of earth: Reason for loss of habitat
- 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.
What will happen if The Sundarban is wiped out to meet the requirement of wood?
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.
Let’s make a list of different animals who fall prey to the greed of the poachers.
|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)
What will happen if The number of tiger or other big carnivores decreases significantly in a forest:
The ‘food web’ and the flow energy in the different level of animal will get hampered. This will destroy ecological balance.
What will happen if some fishes were introduced in a pond which eat other small fishes.
Small fishes will become extinct. These fishes are valuable source of nutrients to our body
(Page no. 243)
What will happen if The amount of rainfall decreases in a certain region?
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.
What will happen if Industrial waste is poured into the river water?
The water will become contaminated, this can spread different diseases, the fishes and other acquatic animals will die.
(Page no. 244)
What will happen in case of large-scale exploitation of a plant that is a source of medicine
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.|
||gaseous pollutants||CO2, SO2, and CO and also oxides of nitrogen.|
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.
|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.
|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
|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.
|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.
|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.|
|Squirrel||fruits and nuts||Yes||shortage of food|
|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|
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
3. Civet Cat
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)
The ability to absorb CO2 in different plants is ……………….
iii) may be same, may be different
Corals become affected due to the increase in ……………….
iii) acidity and temperature
iii) acidity and temperature
Indiscriminate use of chemicals can bring about the destruction of ……………….
iii) animals and plants
iii) animals and plants
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
iv) all are true
Musk is obtained by killing ……………….
Hide is obtained by killing ……………….
Horns of deer are used for……………
i) decorative items
i) decorative items
Reserpine is received from ……………
The habitate of grass, moss, water-lily is ……………
i) near a pond
ii) termite hill
iii) wet dyke
iv) wet land
iv) wet land
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
ii) 30 years
The average temperature of earth had increased by 1°C in last ……………
i) 100 years
ii) 50 years
iii) 200 years
iv) 150 years
i) 100 years
More than 99% of the glacieric are present in ……………
i) North poles
ii) South poles
iii) North and South poles
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.
2. …………… is the average of weather of a particular area for a long period (years).
3. Climatic changes have an important correlation with ……………
4. CO2 is one of the important gases produced by …………… activities.
5. The biggest source of fresh water on the earth is ……………
6. More than …………… of the glaciers are present in North and South poles of earth.
7. The …………… nourishes nine big rivers of Asia.
8. …………… is the shelter for the largest clan of the world.
9. …………… is a type of marine invertebrate animal.
10. The biodiversity of our country is so rich that India is termed as a …………… Nation.
11. We get Quinine from ……………
12. Ranwolfia medicine is derived from ……………
State whether True or False : (1 mark for each question)
1. Climate is the average for small period of time.
2. Hilsa fish lay eggs in the rainy season.
3. Climatic changes does not have any relation with global warming.
4. Some glaciers are also found in Himalayas.
5. Sea level may fall due to the melting of these glaciers.
6. The coastal areas may become flooded if the sea level rises.
7. Glaciers reflect nearly 20% of the sunlight and absorbes 80 of it.
8. Coral exoskeleton is made up of sodium bicarbonate and it protects the body.
9. Dead corals and other organic materials help in forming the coral island.
10. The temperature of Indian Ocean have risen due to global warming.
11. India is the habitat of 30% of all the plants of the world.
12. Introduction of Tilapia and giant African magur in the ponds of rural Bengal posed a huge problem for the existence of indigenous fishes.
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
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)
Which animal eat the egg of the turtle in Galapagos Island?
Dogs and pigs used to eat the eggs of the turtle.
From which country Tilapia and giant Magur came?
They came from Africa.
Name three fishes which are on the verge of being extinct?
Mourala, Punti, Khalse.
The polar ice caps are melting, why?
Due to global warming.
Name some animals that live in the Coral reefs.
Fishes, molusca, echinodermata, sponge, Crustacea etc animals live in the coral reefs.
What is Global Warming?
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.
Name some gases which are present in smoke emitted from different sources.
Carbon dioxide (CO2), Methane (CH4), Nitrous Oxide (N2O). Chloro-Fluoro-Carbon. Sulpher di-oxide (SO2) and particles of dust, Carbon etc.
Name some animals which are on the verge of extinction?
Royal Bengal Tiger, Bengal Vulture. One-horned Rhinoceros. Gangetic Dolphin. Cheetah, Chimpanzee, Orangutan and Gorilla.
Long Questions & Answers : (3 marks for each question)
What is Coral? Write a short note on it.
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.
What is Food Chain?
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.
What do we get from biodiversity?
- 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.
What are the reasons of loss of biodiversity of earth?
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.
Name four Biodiversity hot spots of India.
- 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.
How is plant helpful to us?
- 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.