RBSE Class 12 Biology Important Questions Chapter 16 Environmental Issues

Rajasthan Board RBSE Class 12 Biology Important Questions Chapter 16 Environmental Issues Important Questions and Answers.

RBSE Class 12 Biology Chapter 16 Important Question Environmental Issues

Multiple Choice Questions

Question 1. 
The natural aging of the lake is called
(a) Biomagnification 
(b) Eutrophication 
(c) BOD
(d) None of the above
Answer:
(b) Eutrophication 

Question 2.    
The Environment Act of Government of India was passed in
(a) 1976
(b) 1966
(c) 1986
(d) 1996
Answer:
(c) 1986    

Question 3.    
The agents that bring undesirable changes in the environment arc called
(a) Pollution    
(b) Fragments.
(c) Pollutants    
(d) None of the above
Answer:
(c) Pollutants    

Question 4.    
Particulate matter can be removed by,
(a) Catalytic converter
(b) Converter
(c) Radioactive converter
(d) Electrostatic converter
Answer:
(d) Electrostatic converter

Question 5.    
The petrol used in engines filled with catalytic converter should be
(a) Simple petrol    
(b) Any type of petrol
(c) Unleaded petrol    
(d) None of the above
Answer:
(c) Unleaded petrol    

Very Short Answer Type Questions

Question 1. 
What is the natural aging of a lake called?
Answer:
Eutrophication.

Question 2. 
What is increase in concentration of the toxicant of successive trophic levels called?
Answer:
Biomagnification.

Question 3. 
In which year was the Water Act passed?
Answer:
1974.

Question 4. 
What are the agents which bring about undesirable changes in the environment called? 
Answer:
Pollutants.

Question 5. 
In which year was the Environment Act passed?
Answer:
1986.

Question 6. 
What is the fine powder of recycled modified plastic called?
Answer:
Polyblend.

Question 7. 
Name the pollutant that has degraded the ozone layer.
Answer:
CFCs.

Question 8. 
Name one greenhouse gas.
Answer:
Methane.

Question 9. 
In which year was the Montreal Protocol signed?
Answer:
1987.

Question 10. 
What is the process of restoring a forest called?
Answer:
Reforestation.

Short Answer Type Questions - I

Question 1. 
What is pollution and types of it?
Answer:
The undesirable changes in the physical, chemical and biological characteristics of air, water, land and soil. Any such unwanted and undesirable changes are called pollution. The main types of pollution are air, water, soil and noise pollution.

Question 2. 
Give the names of four" greenhouse gases present in the atmosphere.    
Answer:
Carbon-di-oxide (CO₂), Methane (CH₄), Nitrous oxide (N₂O) and Chlorofluorocarbons (CFCs) are the four green house gases present in the atmosphere.

Question 3. 
How do ultraviolet rays coming from sun affect the living organisms.    
Answer:
Harmful effect of ultraviolet rays are as follows :

• UV rays damages DNA in our body cells causing mutation,
• Causes aging of skin, damage to skin cells and various types of skin cancer.
• High exposure to UV rays causes inflammation of cornea. This is called snow blindness, cataract etc.

Question 4. 
Mention two advantages for preferring CNG over diesel as an automobile fuel. 
Answer:
Two advantages for preferring CNG over diesel as an automobile fuel are as follows :

• It burns more effectively leaving no unburnt remains behind.
• It tends to be cheaper than diesel and petrol.

Question 5. 
Public transport in Delhi uses CNG since 2002. List the advantages of this fuel policy.
Answer:
The advantage of fuel policy involving use of CNG in public transport in Delhi are as follows :

• Compressed Natural Gas (CNG) is a better fuel than petrol or diesel because it is cheaper, burns ihore efficiently, does not pollutethe environment.
• CNG can not be siphoned off by thieves as well as it can not be adulterated like petrol and diesel.

Question 6. 
List four benefits to human life by eliminating the use of CFCs.
Answer:
There are several benefits to human life by eliminating the use of CFCs :

• It prevents the global warming.
• It reduces the ozone degradation.
• It reduces the green house effect.
• It is beneficial to human health in many ways.

Question 7. 
Explain the relationship between CFCs and ozone in the atmosphere.    
Answer: 
The chlorofluorocarbons releases active chlorine (Cl, CIO). This active chlorine gets perched over atmosphere ice crystals and remains functional for a long time. Any single chlorine atom converts one lakh molecules of ozone into oxygen molecule O₂.

Short Answer Type Questions - II

Question 1. 
What is accelerated Eutrophication?
Answer:
Eutrophication is defined as the natural aging of a lake by nutrient enrichment of its water. Natural occuring eutrophication generally takes 1000 years or even more time to occur. But human activities have accelerated this natural occuring process and as a result many lakes are already extinct. It is occuring at faster, rate due to the dumping of nutrient rich and thermal waste into lakes and hence it is called Accelerated Eutrophication.

Question 2. 
An electrostatic precipitator in a thermal power plant is not able to generate high voltage of several thousands. Write the ecological implications because of it.
Answer:
If an electrostatic precipitator in a thermal power plant is not able to generate high voltage of several thousand it would not been able to release electrons, and when the air will be passed through the column inside the precipitator dust particles will not be able to get separated because there are no electrons to bind with dust particles and hence electrostatic precipitator will not be able to control air pollution.

Question 3. 
List two advantages of the use of unleaded petrol in automobiles as fuel.
Answer:
The two advantages of using unleaded petrol in automobiles as fuel are as follows :

• There will be no lead pollution in the environment.
• The catalytic converters used in the exhaust pipes to control harmful leaded petrol emissions. 

Question 4. 
Write the effective remedy found by Ahmed Khan of Bengaluru for the efficient use of plastic waste generated by big cities.
Answer:
Ahmed khan of Bengaluru developed a fine powder called polyblend of recycled modified plastic.
This mixture is mixed with the bitumen and used to lay down the roads. It enhanced the bitumen’s water repellant properties and thus helped to increase road life by many times. In this way, the problems created by plastic waste as solved and plastic manufacturers thought of producing poly blend.

Question 5. 
With the help of a flow chart, show the phenomenon of biomagnification of DDT in an aquatic food chain.
Answer:
Biological magnification is defined as the increase in concentration of toxicants at successive trophic level in a food chain for example DDT.This is because these toxicants can not be metabolised or excreted. Hence, therefore it gets accumulated in an organism and pass on to higher trophic levels in a food chain. Biomagnification of DDT in aquatic food chain : DDT accumulates in the fish eating birds and disturbs calcium metabolism, which results in thinning of egg shells. This results in decline in the population of the fish eating birds. Flow chart of biological magnification. 

Question 6. 
Justify the need for signing of Montreal Protocol by participating nations in 1987.
Answer:
Montreal protocol was signed at Montreal city of Canada in 1987 but effective from 1989 to control the emission of ozone depletion by the various ozone depleting substances like CFCs and aerosols. The balance of ozone production and degradation has been disrupted due to enhancement of ozone degradation by chlorofluorocarbons (CFCs). When CFCs are added to the stratosphere they have permanent and continuous effects on ozone levels.

Long Answer Type Questions

Question 1. 
What is air pollution? Describe the efforts made for-controlling vehicular air pollutions.
Answer:
Air pollution is defined as the presence of toxic chemicals or compounds (including those of biological origin) in the air, at levels that pose a health risk. Air pollution causes injury to all living organisms. Pollutants deleteriously affect respiratory system of humans and animals.
Various effects made for controlling vehicular air pollutions are :

• Phasing out of old vehicles.
• Use of unleaded petrol.
• Promote the use of some alternative vehicular fuel like Compressed Natural Gas (CNG).
• Promote the use of electrical vehicles termed as non polluting vehicles.
• Use of low sulphur petrol and diesel.
• Application of stringent pollution-level norms of vehicles.
• Use of catalytic convertors in vehicles.

Question 2. 
What is pollution? Describe the study and efforts made for the remedy of plastic waste.
Answer:
Pollution is defined as an undesirable change in the physical, chemical and biological characteristics of air, water, land and soil. Pollutants are agents that causes undesirable changes in the environment. The government of India has passed the environment protection act, 1986 to protect and improve the quality of our environment i. e., air, water and soil.

Efforts made for the remedy of plastic waste are as follows :

• Plastic waste is used to lay down the roads by mixing plastic waste with charcoal.
• Under Swachchh Bharat Mission government has banned the single use plastic and imposes a hefty fine on the violators.
• Technologies like incineration and gasification using the plastic waste to generate the electricity, the much needed energy source of today’s world.

Question 3. 
(i) Why and how must the ozone layer in the stratosphere be protected? Explain.
(ii) How do deforestation and greenhouse gases negatively affect our environment? Explain.
Answer:
The ozone layer present in the stratosphere must be protected in many ways for our survival:
Ozone acts as a shield and absorbs ultraviolet radiations from the sun. UV rays are extremely harmful to living organisms.

Ozone gas is continuously formed by the action of UV rays on molecular oxygen and also degraded into molecular oxygen in the stratosphere. In order to protect the ozone layer, there should be a balance between production and degradation of ozone in the stratosphere. In recent past, the balance has been disrupted due to enhancement of ozone degradation by chlorofluorocarbon (CFCs). So in this way the emission of ozone degrading substances like CFCs need to be controlled to protect the ozone layer in the stratosphere.    

Effects of Deforestation : It is the conversion of forested areas to non-forested areas. Its effects are : 

• It increases the level of CO₂ concentration in the atmosphere.
• It results into the loss of biodiversity due to habitat destruction.
• It disturbs, the hydrdogical cycle.
• It leads to soil erosion.
• In extreme cases it also causes destrification. 

Effects of Greenhouse Gases :

• The main greenhouse gases are CO₂, Methane - (CH₄) and CFCs. Their high level in the atmosphere allow the heat waves to reach earth, but prevent their escape and earth becomes warm. This increased temperature in last three decades has caused changes in precipitation patterns.
• The increased temperature also causes Eh-nino effect melting of the polar ice caps and Himalayan snow.