Environmental Issues(12th Grade > Biology ) Questions and Answers
Explanation:-
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.
Explanation:-
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.
Explanation:-
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.
Explanation:-
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.
Explanation:-
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.
Explanation:-
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.
Explanation:-
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.
Explanation:-
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.
Explanation:-
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.
Explanation:-
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.