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12th Grade > Biology

ENVIRONMENTAL ISSUES MCQs

Total Questions : 38 | Page 1 of 4 pages
Question 1. Regarding the assertion and reason, choose the correct answer.
Assertion [A]: Global warming reduces pH levels in the oceans.
Reason [R]: Carbon dioxide dissolves in water to form carbonic acid.
  1.    Both A and R are true, and R explains A
  2.    Both A and R are true, but R does not explain A
  3.    A is true and R is false
  4.    Both A and R are false
 Discuss Question
Answer: Option A. -> Both A and R are true, and R explains A
:
A
Global warming mainly results from an increase in the levels of greenhouse gases such as carbon dioxide and methane in the atmosphere. Carbon dioxide dissolves in water to form carbonic acid. This would result in an apparent decrease in pH levels in the oceans, adversely affecting marine life.
Question 2. State whether true or false:
The Chipko movement was started by Amrita Devi
 in 1973 to protect trees from being cut.
  1.    True
  2.    False
  3.    A - 3, B - 1, C - 2, D - 4
  4.    A - 1, B - 3, C - 2, D - 4
 Discuss Question
Answer: Option A. -> True
:
A
In 1973, a Bishnoi woman by the name Amrita Devi showed exemplary courage by protecting trees from being cut. She sacrificed her life along with her three daughters by hugging the trees to protect them from axe men. The Government of India has recently instituted the Amrita Devi Bishnoi Wildlife Protection Award for individuals or communities from rural areas that have shown extraordinary courage and dedication in protecting wildlife. The vision of women fired the spirit of environmentalists the worldover.The movement spread rapidly across the Himalayan region in the 1970s. It spawned action in other places: Appiko Movement in Karnataka, Chilka Lake Agitation in Orissa, and Narmada Bachao Andolan.
Question 3. Regarding the assertion and reason, choose the correct option.
Assertion [A]: UV radiation causes photo-dissociation of ozone into Oand O, thus causing damage to the ozone layer.
Reason [R]: The ozone hole has been the major cause of global warming and climate change.
  1.    Both A and R are true and R is the correct explanation for A
  2.    Both A and R are true but R is not the correct explanation for A
  3.    A is true but R is false
  4.    Both A and R are false
 Discuss Question
Answer: Option D. -> Both A and R are false
:
D
UV radiation does not cause photodissociation of ozone into O2 and O.Instead, it takes part in the formation of ozone in two steps.
O2---> O + O
O2+ O ---> O3
Due to certain carelesshuman activities, the ozone layer in the stratosphere has beenthinning down in certain areas, which are beingknown as"ozone hole". The ozone hole has beenresulting in rain failure, increased incoming radiation, cancers and a reduction in crop production. Global warming and climate changes are mainly caused due to an increase in the amounts of greenhouse gases in the atmosphere.
Question 4. With regard to the assertion and reason, choose the correct option.
Assertion [A]: α, β and γ rays are emitted by disintegration of atomic nuclei of radioactive elements.
Reason [R]: Nuclear fallout contains radioactive elements. 
  1.    Both A and R are true and R is the correct explanation for A
  2.    Both A and R are true but R is not the correct explanation for A
  3.    A is true but R is false
  4.    Both the A and R are false
 Discuss Question
Answer: Option B. -> Both A and R are true but R is not the correct explanation for A
:
B
An element subject to spontaneous degeneration of its nucleus accompanied by the emission of alpha particles, betaparticlesor gamma rays is called a radioactive element. Nuclear fallout refers tothe radioactive particles that fall on to the earth as a result of a nuclear explosion. Fallout particles vary in size from thousandths of a millimeter to several millimeters. Much of this material falls directly back down close to ground where the explosion happenedwithin several minutes after the explosion, but some get dispered by winds over long distances. The fallout usually gets suspendedin the atmosphere, 6 to 7 km above the earth's surface. These radionuclides alsooften settle down by rain and get mixed with soil and water. From there, they can easily enter the food chain and finally get deposited in the human body where they cause serious health hazards.
Question 5. Human activities that lead to environmental degradation are
  1.    Burning of fossil fuels
  2.    Tools for hunting
  3.    Extensive agriculture
  4.    All of the above
 Discuss Question
Answer: Option D. -> All of the above
:
D
Human activities such as taming of fire and hunting began affecting other organisms. One such effect was an increased species extinction rate. The burning of coal or other fossil fuels also lead to air pollution. Increased agriculture leads to deforestation and the use of fertilizers in farming leads to water pollution.
Question 6. The major pollutant behind the infamous `Bhopal’ leakage was
  1.    Isocyanic acid        
  2.    Methylene
  3.    Methyl isocyanate
  4.    Hydrogen cyanide
 Discuss Question
Answer: Option C. -> Methyl isocyanate
:
C
The Bhopal Gas Tragedy, 1984, was a catastrophe that had no parallel in the world’s industrial history. In the early morning hours of December 3, 1984, a rolling wind carried a poisonous gray cloud from the Union Carbide Plant in Bhopal, Madhya Pradesh (India). Forty tons of toxic gas (Methyl isocyanate, MIC) got accidentally released from Union Carbide’s Bhopal plant, which leaked and spread throughout the city.
Question 7. Rain is called acid rain when its pH is below
  1.     7
  2.    6.5
  3.    6
  4.    5.6
 Discuss Question
Answer: Option D. -> 5.6
:
D
Acid rain is a term referring to precipitation (rain, snow, sleet, fog, cloudwater, dew etc.) mixed with acidic components. Water has a neutral pH of 7. Liquids with a pH less than 7 are acidic, and those with a pH greater than 7 are alkaline. Unpolluted rain has an acidic pH, but usually no lower than 5.7, because carbon dioxide and water in the air react together to form carbonic acid, which is a weak acid. But the presence of pollutants such as oxides of sulphur and nitrogen cause further acidification of rainwater, by forming sulphuric acid and nitric acid, which further lower the pH of rainwater, making it acidic.
Question 8. State whether true or false:
Ozone depletion can cause skin cancers and snow blindness.
  1.    True
  2.    False
  3.    To conserve species diversity
  4.    To conserve fossil fuels
 Discuss Question
Answer: Option A. -> True
:
A
Ozone depletion allows harmful UVB radiations to reach Earth's surface. It causes aging of skin, damage to skin cells and various types of skin cancers. In the human eye, the cornea absorbs UVB radiation, and a high dose of UVB causes inflammation of the cornea, resultingina condition known commonly as snow blindness.
Question 9. Identify the natural sources of radiations.
  1.    Carbon-40
  2.    Gamma rays
  3.    Nuclear power plants
  4.    X-rays
 Discuss Question
Answer: Option A. -> Carbon-40
:
A
Atomic radioactive minerals are one of the natural sources of radioactive pollution. Radioactive elements like uranium, thorium, radium, isotopes of potassium (K-40) and carbon (C-40) are naturally occurring. Cosmic rays originating from the sun arealso a natural source of radiation. Anthropogenic sources include radiations that are employed for diagnostic and therapeutic applications. X-rays are used in general radiology and CT scan. Gamma rays are used in the treatment of cancer. In all these procedures, we are exposed to varying doses of radiations.
Question 10. Assertion [A]: Eutrophication shows an increase in productivity of water.
Reason [R]: With increasing eutrophication, the diversity of phytoplankton increases.
  1.    Both A and R are true and R is the correct explanation for A
  2.    Both A and R are true but R is not the correct explanation for A
  3.    A is true but R is false
  4.    Both A and R are false
 Discuss Question
Answer: Option B. -> Both A and R are true but R is not the correct explanation for A
:
B
Eutrophication is the enrichment of an ecosystem with chemical nutrients, typically compounds containing nitrogen, phosphorus, or both. It is a natural state in many lakes and ponds which have rich supply of nutrients. Eutrophication becomes excessive however, when abnormally high amounts of nutrients from sewage, fertilisers, animal waste and detergententer streams and lakes causing excessive growth or bloomof microorganisms.With increasing eutrophication, the diversity of the phytoplankton community of a lake increases and the lake finally becomes dominated by bluegreen algae.

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