Environmental Science MCQ – Asked in Previous Years, WBCS Mains

Answer – B. Exhaust of automobile
Explanation-
▪ Tetraethyl lead (TEL) was previously used as an additive in gasoline to improve the octane rating and reduce engine knocking. It was primarily used in leaded gasoline, which was commonly used in automobiles.

▪ When the gasoline was burned in the engine, tetraethyl lead was released into the exhaust as a byproduct, contributing to air pollution. However, due to its harmful effects on human health and the environment, the use of tetraethyl lead in gasoline has been phased out in many countries.

Answer – D. Gasoline
Explanation-
▪ Gasoline is a conventional fossil fuel derived from petroleum and is not considered a biofuel. Biofuels, on the other hand, are fuels produced from renewable biological sources.

▪ Vegetable oil, green diesel (produced from biomass or renewable feedstocks), and biogas (produced through the anaerobic digestion of organic matter) are examples of biofuels.

▪ Gasoline, being derived from non-renewable fossil resources, does not fall under the category of biofuels.

Answer – B. Silent Valley Movement
Explanation-
▪ The Lion-tailed Macaque (Macaca silenus) is an endangered primate species found in the Western Ghats of India.

▪ The Silent Valley Movement, which took place in the 1970s, was focused on protecting the Silent Valley National Park in Kerala, India, from proposed hydroelectric dam construction.

▪ The presence of the Lion-tailed Macaque and its unique habitat within the Silent Valley National Park played a significant role in raising awareness and generating support for the conservation of the area.

Answer – A. Water Pollution
Explanation-
▪ Activated sludge plants are wastewater treatment systems that use microorganisms to break down organic matter and remove pollutants from water.

▪ The process involves introducing a mixture of wastewater and microorganisms (known as activated sludge) into a treatment tank. The microorganisms consume the organic pollutants in the wastewater, reducing its pollution levels.

▪ Through a series of treatment steps, including aeration and sedimentation, activated sludge plants effectively treat wastewater, thereby reducing water pollution before it is discharged into the environment.

Answer – A. highly productive water body rich in nutrients.
Explanation-
▪ An ‘eutrophic’ water body refers to a highly productive water body that is rich in nutrients, particularly nitrogen and phosphorus. These nutrients support the growth of abundant aquatic plant life, such as algae and other aquatic vegetation.

▪ While initially, this high productivity may seem beneficial, excessive nutrient enrichment can lead to harmful algal blooms, oxygen depletion, and overall ecological imbalance in the water body. Eutrophication is a natural or human-induced process that can result from agricultural runoff, sewage discharge, or other factors.

Answer – C. In-situ conservation
Explanation-
▪ In-situ conservation refers to the conservation of biodiversity within its natural habitat or original ecosystem. It involves the protection, management, and preservation of ecosystems, habitats, and species in their natural surroundings.

▪ In-situ conservation focuses on maintaining the ecological processes, interactions, and evolutionary dynamics that occur in natural ecosystems. Examples of in-situ conservation measures include establishing protected areas, national parks, wildlife sanctuaries, and biosphere reserves.

Answer – B. Escherichia coli
Explanation-
▪ Escherichia coli (E. coli) is a common indicator organism used to assess water pollution and the presence of fecal contamination in water bodies. E. coli is a bacterium that naturally inhabits the intestines of warm-blooded animals, including humans.

▪ Its presence in water indicates the possible presence of fecal matter and associated pathogens. Monitoring E. coli levels in water is important for assessing water quality, especially in terms of microbial contamination and the potential health risks associated with waterborne diseases.

Answer – B. London smog
Explanation-
▪ Sulphur dioxide (SO₂) smog, characterized by the presence of high levels of sulphur dioxide in the atmosphere, is commonly known as London smog. The term originated from the severe air pollution episodes that occurred in London, particularly in the 19th and mid-20th centuries.

▪ The smog, often exacerbated by the burning of coal, led to a combination of sulphur dioxide, particulate matter, and other pollutants, resulting in dense, hazardous fog-like conditions with reduced visibility and adverse health effects.

Answer – B. Respiratory problems
Explanation-
▪ Air pollution is known to cause various adverse health effects, and one of the significant impacts is respiratory problems. Inhalation of pollutants present in polluted air can lead to respiratory issues such as coughing, wheezing, asthma, bronchitis, and other respiratory tract infections.

▪ Prolonged exposure to air pollution, especially fine particulate matter (PM2.5), nitrogen dioxide (NO2), sulfur dioxide (SO2), and ozone (O3), can significantly increase the risk of respiratory diseases and exacerbate existing respiratory conditions.

Answer – A. Ocean
Explanation-
▪ The ocean constitutes the largest ecosystem on Earth. It covers more than 70% of the planet’s surface and encompasses a diverse range of habitats and ecosystems, including coral reefs, open ocean, deep-sea ecosystems, estuaries, and coastal zones.

▪ The ocean plays a crucial role in regulating the Earth’s climate, supporting biodiversity, providing food resources, and influencing weather patterns. Its vastness and ecological significance make it the largest and most important ecosystem on our planet.