Detailed explanations in West Bengal Board Class 8 Science Book Solutions Chapter 5 Analysis of Natural Phenomena offer valuable context and analysis.
WBBSE Class 8 Science Chapter 5 Question Answer – Analysis of Natural Phenomena
Fill up the blanks : (See Text Book Page 172)
|Name of the disease||How transmitted||Responsible germ||Means to avoid the disease|
|1. Cholera||Uncovered food unclean environment||vibrio cholera||taking pure food & drink|
|2. Maleria||biting of mosquito||Plasmodium vivax||avoid mosquito biting|
|3. Plague||biting of rats||Yersinia pestis||avoid rat biting|
|4. AIDS||body fluid & mucous||HIV virus||consciousness|
|5. Kala Azar||carrier sand fly||Leishmania donovani||consciousness|
Write down what problems may be faced for the absence of proper food habits arid right life style.
|Food habit and life style||Problems likely to be faced|
|1. Intake of excess carbohydrate||risk of heart disease|
|2. Intake of excess carbohydrate||risk of diabetes|
|3. Staying awake at night and insufficient sleep||headache, blood pressure|
|4. Working with computer for long duration without interruption||spondylities, headache|
|5. Smoking and intake if intoxicating substances||risk of cancer|
|6. Excessive use of mobile phone||eye problem, cancer|
Class 8 Science Chapter 5 Question Answer West Bengal Board – Analysis of Natural Phenomena
Multiple Choice Questions & Answers : (1 mark for each question)
During thunder the air —
iii) attracts violently
The height of a storm cloud is generally —
i) 3-4 km.
ii) 7-8 km.
iii) 12-13 km.
iv) 17-18 km.
iii) 12-13 km.
The lighting conduction is buried at least —
ii) 10-12 P
iv) 20-22 feet deep into the ground.
i) 5-6 feet
An epidemic disease is —
i) heart disease
iv) skin disease
Mosquito-born fatal disease dengue first broke out in Kolkata in the year —
Cholera generally causes from —
i) polluted air
ii) polluted water
iv) polluted food
ii) Polluted water.
The word ‘Malaria’ means —
i) bad water
ii) bad light
iii) bad air
iv) bad soil
iii) Bad air
The carrier of Malaria disease —
The medicine of Kalazar was invented by —
ii) Jagadish chandra Bose
iii) Satyandranath Dtitta
iv) Upendranatk Brahmachari
iv) Upendranath Brahmachari
Blood appears in stool in —
Tuberculosis disease is —
Treatment of Tuberculosis is called —
Types of Hepatitis are —
The virus responsible for AIDS disease —
Another name of small Pox is —
i) Red plague
iii) white plague
iv) green plague
i) Red plague
State whether True or False :(1 mark for each question)
1) Lighting inducts the earth with negative charge.
2) Almost even, day at some part of the world lightning occurs due to thunderstorms which are at least 4,000.
3) The clouds become charged to the friction of clouds or that of the water
4) Generally clouds bring in thunderstorms and rain.
5) Clouds are formed by (lie condensation of tater deoplets.
6) The height of a storm cloud is generally 4-5 km.
7) The water droplets became charged when the clouds rise and come down at the time of storm.
8) The lower edges of tite clouds are inducted with positive charge.
9) There is potential difference between the sky and the earth.
10) If there is potential difference, then lightning may occur between two different cloud or parts of same cloud.
Fill in the blanks : (1 mark for each question)
1) The part of the train which is in contact with the electric line is called ________
2) The electrical cells used in radios or torches is called ________
3) In our country, thunderstorms and highlighting seldom occur in ________
4) In an atom (lie electron and the proton are ________ particles.
5) Atoms arc uncharged because the number of protons and electrons in atom is ________
6) If an electron is released from on atom, then the atom becomes a ________
7) In winter if plastic comb is used for combing hair, it acquires ________ charge.
8) ________ is a high-energy electric discharge and it can cause great harm.
9) The flow of electric charge is called an ________.
10) Lighting is that cell in nature which maintains the ________ of electric charge high up in the sky and on earth.
2) dry cell.
4) electrically charged
6) positive ion
9) electric current.
10) potential difference.
Very Short Questions & Answers : (1 mark for each question)
Which cells are called dry cell?
The electricals cells used in radios or torches are called dry cell.
What is pentograph?
The part of the train which is in contact with the electric line is called pentograph.
Who did experiment on electric spark?
Famous scientist Benjamin Franklin.
Which charge is inducted in the lower edges of the clouds?
Which charge is inducted the upper edges of the clouds?
What is the reason that opposite charges accumulate at different edges of the clouds?
Potential difference between the sky and the earth. ,
What is the work of lighting conductor?
Lighting conductions a device that protects houses and electrical equipments within the house.
What is an epidemic?
When hundreds of people die at the same time in every year due to out break of a fatal disease, then that disease is declared as an epidemic.
Write name of some epidemic diseases.
Some epidemic diseases are — Malaria, Aids, Influenza, Dengue etc.
Which diseases occur in spring season?
The onset of spring sees a spirit in diseases like Measles and Chicken Pox.
Which diseases are common in winter season?
Infection of the upper tracts of the respiratory organ is generally common in winter months.
When stomach infection is usually high?
Stomach infection is usually high in summer.
What is the cause of Cholera disease?
Cholera disease is generally caused from polluted water, uncovered and fly infected food and unhyginenic environment.
Name the germ of disease Cholera.
Name the germ that female anopheles mosquito carries.
Plasmodium vivax or Plasmodium falciparum.
Which mosquito carries the germ of Dengue?
A type of mosquito called Aedes Egypt carries the germ of Dengue.
Name the bacteria resposible for Plague.
Yersimia pestis is responsible for plague.
Name the type of fly which carries the bacteria from body of rat afflicted with plague.
Who invented the vaccine of plague?
In 1987, Waldemar Haffkine invented the vaccine of piague in Bombay.
Name the protozoa and the carrier fly which causes Kalazar.
The name of protozoa is Leishmania and the carrier fly is Sand fly.
Who invented the vaccine of small pox?
British scientist Edward Jenner invented the vaccine of small pox.
What is SARS?
It is an epidemic disease Severe Acute Respiratory Syndrome.
What is DOTS?
The deadly disease Tuberculosis is prevented through DOT or Directly Observed Treatment.
Name the bacterium resposible for Tuberculosis.
How many types of Hepatitis is there?
There are five types of Hepatitis A, B, C, D and E.
How A and E types of Hepatitis occur.
A and E types of infection is caused by contaminated food and water.
How B, C and D type of Hepatitis occur?
B, C and D type of Hepatitis infection occurs through the medium of the body fluid and blood of human.
Which day has been declared by WHO as World Hepatitis Day?
World Health Organisation (WHO) has declared 28th July as World Hepatitis Day.
What is the full form of AIDS and HIV?
Full form of AIDS is – Acquired Immune Deficiency Syndrome and of HIV — Human Immuno dificieancy Virus.
Name some non-infectious diseases which have assumed epidemic dimensions.
Some non-infections diseases such as diabetes, hypertension, cancer, mental illness also have assumed epidemic dimensions.
Short Questions & Answers : (2 marks for each question)
What are electrolytes? Give example.
The compounds which are able to conduct electricity in a fused state or in a solution, are called electrolytes. Examples of electrolytes are acid or alkyl solution, aqueous solution of a salt, fused Nacl etc.
What is electricity?
Electricity is a form of energy and can, thus, be converted to heat, light and even sound. Electricity is caused due to motion of electric charges, which causes electric current to be generated.
What is static electricity?
The accumulation of electrical charges on the surface of a material, usually an insulator or a non-conductor of electricity, gives rise to the concept of static electricity. This electricity is, called ‘static’ because there is no current flowing. However, static electricity can cause sparks, shocks or materials to cling to each other.
What is ion? How it can become positive or negative ion?
If in an atom number of protons and number of electrons are equal then that atom is called ion. But if the number of protons exceed the number of electrons then the atom become, a positive ion. If the number of protons is less than that of electrons, then the atom becomes a negative ion.
Write short note on Cholera.
This disease generally causes from polluted water, uncovered and fly infected food unhygienic environornent, The body is dehyadrated with bouts of vomiting. The skin becomes foggy and bluish. It is a fatal desease, so proper treatment is must for survival. Cholera is caused by a germ known as Vibrio cholerae.
Write short note on Malaria,
Malaria is a mosquito carried discease. A female anopheles mosquito carries a germ called Plasmodium vivax or Phasmodium falciparum and injects it in the blood stream of a healthy person to cause malaria. High fevers with tremors are a common symptom. Headache and enlargement of splen and liver, joint pain and body ache are other symptoms. If may be fatal if not prompty treated.
Write short note on Dengue,
A type of mosquito called Aedes egypti carries the germ of this disease. The germ is known as flavi virus. High fever, headache, joint pain and lowering of platelet count to a dangerous level causing obstruction and coagulation of blood are the common incidents. Oozing of the blood is the main symptom of the disease, by destroying the white blood corpuscles (WBC). Unless treated in time, dengue can be fatal.
Write short note on Plague.
This disease is transmited by rats to the human body. A bacterium called Yersinia pestis is responsible for this disease. The main symptoms are lung infection, blood clothing, severe pain from swelling of the lymph gland, vomiting and oozing of blood with cough.
This disease can be transmitted by various means such as sneezing, direct body contact, touching infected soil and even from bites of flying insects. A type of fly called Xenopsylla cheopis carries the bacteria from body of rat afflicted with plague.
Write short note on Tuberculosis.
Mycobacterium tuberculosis is responsible for this disease. This bacterium attacks the lungs of human beings. Tuberculosis can occur in intestine and bones. This disease is highly infectious. Infection can occur from cough and mucous an even through spits and saliva.
Symptoms of the disease are severe cough, with the letting of blood, profuse sweating and gradual loss of weight. It can be cured by DOTS or directly observed treatment, short course.
Long Questions & Answers : (3 marks for each question)
Explain how cloud forms and bring rain?
The air containing water vapour rise upward. Air from surrounding region rushes toward this place and also starts to move upward. In the upper layer of the atmosphere the temperature and pressure of air is less. The water vapour rises up into the sky and condenses. As a result the vapour converts into droplets thus cloud is formed.
A time comes when the water droplets become so heavy that they come down due to gravity. Even the winds of high speed in the upper layer of the atmosphere cannot stop the downward motion of water droplet. By this time the formation of clouds for thunderstorm has completed. Then the wind also starts to go downward. In such a situation rain and storm begin on earth.
Explain how lightning and thunder occur.
The lower portion of a cloud generally carries negative charges and the upper portion carries positive charges. Air of the atmosphere acts as an insulator and the charges do not flow. When a huge amount of charge builds up and when clouds with unlike charges come close to each other, the insulation of air breaks down and there is a heavy electric discharge between two cloud having opposite charges or between a charged cloud and the ground.
This causes a large amount of energy to be in the form of heat, light and sound. The flash of light is the lighting we see, and the large amount of heat causes expansion and vibration of air resulting in the thundering sound.
Explain how lightning causes harm and precautions we can take during lightning.
Lightning can cause great harm. It can kill human beings and animals, destroy buildings, melt metals and also cause fires. We should take the following precautions during lightning —
- We should try to take shelter inside a building, or even in a car or a truck. We should avoid taking shelter in sheds with metal roofing.
- Do not stand under a tree. As lighting tends to strike tall objects, the true has a possibility of getting struck by lightning.
- Do not run across an open field. Also, do not stand on high ground. Squat down on the low-lying ground if safe place cannot he found.
What is a lightning conductor, how it works?
Lightning conductor is a device that protects houses and electrical equipments within the house. A metallic rod is installed at the highest point of the building. At the highest point of the rod, there exist some small skewers. A wide metal plate is buried at least 5-6 feet deep into the ground. A thick wire of good conductor is connected to the metal plate and the rod.
This system protects the house from lighting. The high voltage of current produced in lightning is transferred to the earth through the easy route of the wire. Even if lightning strikes the house, no damage occurs to the house.
Define the types of epidemic
Types of epidemic are —
- Epidemic front common source : This types of epidemic is caused by any disease creating germ but not always (like poisoning of water, air, food or soil. Typical examples are Bhopal Gas Tragedy or Japanis Minamata disease).
- Epidemic from infection : Epidemic of this type is directly transmitted by one person to the other or through the medium of a living carrier of by infection front the body of living being (Measles, Small Pox, Influenza, Malaria)
- Slowly Infectious epidemic : Lung Cancer, Coronary heart Disease.