Environmental Science MCQ – Asked in Previous Years, WBCS Mains

Answer – D. Both A. and B.
Explanation-
▪ Biomes are large ecological areas characterized by distinctive plant and animal communities. They represent major habitats and are shaped by climate, topography, and other environmental factors.

▪ Biomes encompass a wide range of ecosystems, including forests, grasslands, deserts, tundra, aquatic ecosystems, and more. Each biome is associated with specific plant communities and supports various animal communities that are adapted to the prevailing conditions and form interconnected ecological networks.

Answer – A. Man and Biosphere.
Explanation-
▪ MAB stands for “Man and Biosphere.” It refers to the Man and Biosphere Program, an interdisciplinary initiative launched by UNESCO (United Nations Educational, Scientific and Cultural Organization) in 1971.

▪ The MAB program aims to promote the sustainable use and conservation of biological diversity, taking into account the social, economic, and environmental aspects of human interaction with natural systems. It encourages research, capacity building, and the establishment of biosphere reserves as model areas for sustainable development.

Answer – A. leaf surface
Explanation-
▪ Loss of water through transpiration is highest from the leaf surface of plants. Transpiration is the process by which water evaporates from the stomata, small openings on the surface of leaves. Leaves have a large surface area covered with stomata, which allows for efficient exchange of gases but also leads to water loss. Transpiration plays a vital role in plant physiology, facilitating nutrient uptake, cooling of the plant, and maintenance of turgidity. However, excessive water loss can result in water stress for the plant.

Answer – C. 20 Km.
Explanation-
▪ The tropopause is the boundary between the troposphere (the lowest layer of the Earth’s atmosphere) and the layer above known as the stratosphere. The maximum width of the tropopause is approximately 20 kilometers (km).

▪ This width can vary based on factors such as latitude, season, and weather patterns. Above the tropopause, the temperature generally stops decreasing with height, and the stratosphere begins where the ozone layer is located.

Answer – A. 80 Km.
Explanation-
▪ The thermosphere is the fourth layer of Earth’s atmosphere, and it extends from 80 kilometers to 600 kilometers above the Earth’s surface. The thermosphere is the hottest layer of the atmosphere, and its temperature can reach up to 2,000 degrees Celsius. The thermosphere is also where the aurora borealis (northern lights) and the aurora australis (southern lights) are produced.

Answer – B. Pseudomonas.
Explanation-
▪ Pseudomonas putida, a species renowned for its ability to degrade aromatic compounds such as hydrocarbons, is extensively employed in bioremediation and oil spill decontamination processes.

▪ Rhizobium meliloti, on the other hand, is a soil bacterium that plays a crucial role in fixing atmospheric nitrogen. Lastly, Bacillus thuringiensis, another soil bacterium, finds application in biological pest control methods.

Answer – B. SO₂
Explanation-
▪ Stone cancer is a phenomenon in which the discoloration of stones/marbles occurs due to acid rain. Acid rain is formed when sulfur dioxide and nitrogen oxides react with water vapor in the atmosphere. These pollutants are released into the air by power plants, factories, and vehicles. When acid rain falls on rocks and buildings, it can cause them to corrode and discolor.

▪ The Taj Mahal in India is a famous example of a building that has been affected by stone cancer. The marble of the Taj Mahal has turned yellow and black due to the acid rain that falls in the area.

▪ Other gases that can contribute to stone cancer include NO2 (nitrogen dioxide), HCl (hydrogen chloride), and HF (hydrogen fluoride). However, SO2 is the most common gas involved in stone cancer.

Answer – A. 20°C.
Explanation-
▪ The temperature of water for measuring Biochemical Oxygen Demand (BOD) should be maintained at 20°C. BOD is a measure of the amount of dissolved oxygen consumed by microorganisms during the decomposition of organic matter in water. It is an important indicator of water quality and the presence of organic pollution.

▪ Standardized BOD tests are conducted at a controlled temperature of 20°C to ensure consistency and comparability of results. The test involves measuring the decrease in dissolved oxygen over a specific period, usually 5 days.

Answer – B. 1984.
Explanation-
▪ Silent Valley National Park, located in Kerala, India, became a national park in the year 1984. The park is known for its rich biodiversity and unique tropical rainforest ecosystem. It is home to various species of plants, animals, and birds, including many endangered and endemic species. Silent Valley National Park is recognized for its ecological significance and is protected to preserve its pristine natural environment.

Answer – A. Rajendra Singh.
Explanation-
▪ Rajendra Singh is associated with rainwater harvesting. He is an Indian water conservationist and environmentalist who is often referred to as “Waterman of India.” Rajendra Singh has played a significant role in promoting community-based water management and rainwater harvesting techniques in India, particularly in the arid regions of Rajasthan. His efforts have focused on reviving traditional water management systems, constructing check dams, and promoting water conservation practices to address water scarcity issues.