Set 9 | Important Environment Pollution MCQs

Correct Answer is C.

B.O.D. (Biochemical Oxygen Demand) is a measure of the amount of oxygen required by microorganisms to decompose organic matter in water. A high B.O.D. indicates that there is a large amount of organic matter present, which is often due to contamination by sewage or other organic pollutants. This organic matter consumes oxygen as it decomposes, reducing the oxygen available for aquatic life and indicating poor water quality.

• [A] Receiving minerals is incorrect because minerals do not directly contribute to high B.O.D.
• [B] Being aerated is incorrect because aeration increases oxygen levels, whereas high B.O.D. indicates oxygen depletion.
• [D] Atrophic is incorrect because “atrophic” refers to a lack of nutrients, which is not related to high B.O.D.

Correct Answer is C.

• Eutrophication refers to the over-enrichment of nutrients, such as nitrates and phosphates, in a lake or other water body, often caused by runoff from land.
• This nutrient overload leads to the rapid and dense growth of plant life, particularly algae. As these algae proliferate and eventually die, their decomposition consumes large amounts of dissolved oxygen in the water, depleting oxygen levels and harming aquatic ecosystems.
• Common sources of these nutrients include detergents, fertilizers, and sewage that are discharged into water systems.

Correct Answer is B.

• The BOD (Biochemical Oxygen Demand) is highest in the Ganga river between Kanpur and Allahabad because Kanpur releases a significant amount of pollutants into the river.
• This heavy discharge of contaminants leads to elevated BOD levels in this stretch of the river.

Correct Answer is A.

Bioremediation refers to the process of using living organisms, such as bacteria, fungi, or plants, to break down, remove, or neutralize toxic pollutants from the environment. This natural process helps clean up contaminated soil, water, or air by converting harmful substances into less toxic or non-toxic forms. It is an environmentally friendly approach to addressing pollution and restoring ecosystems.

• [B] Biocontrol of pathogens and pests refers to biological pest control, not bioremediation.
• [C] Transplantation of organs in the body is unrelated to bioremediation and pertains to medical procedures.
• [D] Diagnosis of diseases by the help of microorganisms is also unrelated and refers to medical diagnostics.

Correct Answer is C.

• The process of removing toxic pollutants from the environment using microorganisms is known as bioremediation. This technique leverages and accelerates the natural biodegradation processes that occur in nature to clean up pollution.
• However, bioremediation has limitations, as it cannot effectively treat pollutants containing heavy metals, such as cadmium and lead. These metals are challenging to break down or remove completely using microorganisms.
• To overcome some of these limitations, genetic engineering can be employed to design specialized microorganisms for bioremediation.
• For example, the “superbug” Pseudomonas putida, created through genetic engineering, has proven effective in addressing oil spills in oceans. Such advancements highlight the potential of bioremediation in tackling environmental pollution.

Correct Answer is D.

• Zinc, copper, and nickel are heavy metals that can act as water pollutants when present in excessive amounts. They often enter water bodies through industrial discharges, mining activities, or agricultural runoff, and can harm aquatic life and human health.
• On the other hand, sulphur dioxide (SO₂) is primarily an air pollutant. It is released into the atmosphere through the burning of fossil fuels and industrial processes. While sulphur dioxide can contribute to acid rain, which indirectly affects water bodies, it is not directly classified as a water pollutant. Therefore, the correct answer is [D] Sulphur Dioxide.

Correct Answer is D.

• The problem of water pollution with arsenic is most severe in West Bengal, particularly in the districts along the Ganges-Brahmaputra delta.
• Arsenic contamination in groundwater is a significant issue in this region due to natural geological processes that release arsenic from sediments into the water.
• This contamination poses serious health risks, including skin lesions, cancers, and other diseases, to the population relying on groundwater for drinking and irrigation.
• While arsenic contamination is also reported in parts of other states like Bihar, Uttar Pradesh, and Assam, West Bengal is notably the most affected.

Correct Answer is A.

• The Chernobyl accident refers to the catastrophic nuclear disaster that occurred on April 26, 1986, at the Chernobyl Nuclear Power Plant in Ukraine (then part of the Soviet Union). It is considered the worst nuclear power plant accident in history.
• The explosion and subsequent fire released large amounts of radioactive materials into the atmosphere, causing widespread environmental and health impacts. The disaster is not related to earthquakes, floods, or acid rain.

Correct Answer is B.

• The most toxic metal pollutant found in automobile exhaust is lead. Historically, lead was added to gasoline as an anti-knocking agent in the form of tetraethyl lead.
• When this leaded gasoline is burned, it releases lead particles into the air, which can settle on soil and water, causing severe environmental and health hazards.
• Lead is highly toxic, especially to children, as it can cause neurological damage, developmental issues, and other serious health problems.
• While copper and cadmium are also toxic metals, they are not typically associated with automobile exhaust in the same way as lead.
• Modern vehicles now use unleaded gasoline, significantly reducing lead emissions, but lead remains the most notorious toxic metal pollutant from automobile exhaust historically.

Correct Answer is C.

• The Damodar River is often referred to as a ‘biological desert’ due to the high levels of industrial pollution it carries.
• The river flows through the coal-rich regions of Jharkhand and West Bengal, and its water is heavily contaminated with industrial effluents, coal ash, and other pollutants from mining and industrial activities.
• This pollution severely degrades the river’s ecosystem, making it inhospitable for most aquatic life, hence the term “biological desert.”
• While rivers like the Yamuna, Periyar, and Mahanadi also face pollution issues, the Damodar River is particularly notorious for its severe industrial contamination.