Daily Static MCQs Quiz for UPSC, IAS, UPPSC/UPPCS, MPPSC. BPSC, RPSC & All State PSC Exams
Subject : Environment & Ecology
1. Hot water discharged by industries is considered as a water pollutant because:
1. Higher water temperature generally increases the level of
dissolved oxygen of water.
2. High temperature limits oxygen dispersion into deeper waters, contributing to
anaerobic conditions in deep water.
Which of the above statements is/are correct?
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Answer: (B)
Explanation:
- Elevated temperature typically decreases the level of dissolved oxygen of water. This can harm aquatic animals such as fish, amphibians and other aquatic organisms. Thermal pollution may also increase the metabolic rate of aquatic animals, as enzyme activity, resulting in these organisms consuming more food in a shorter time than if their environment were not changed. Hence statement 1 is incorrect.
- High temperature limits oxygen dispersion into deeper waters, contributing to anaerobic conditions. This can lead to increased bacteria levels when there is ample food supply. Many aquatic species will fail to reproduce at elevated temperatures. Hence statement 2 is correct.
2. Increased Snow cover on a water body can lead to:
1. Improved oxygen exchange and nutrient recycling in the
lake
2. Sudden spurt in phytoplankton population which are not dependent on
photosynthesis
3. A condition of winterkill causing large scale death of fishes and organisms
Select the correct answer using the code given below:
(a) 1 and 2 only
(b) 2 and 3 only
(c) 3 only
(d) 1, 2 and 3
Answer: (C)
Explanation: Phytoplankton floats on top surface of water bodies and require sunlight to thrive. Ice cover will reduce their breeding grounds and population.The snow cover blocks exchange of nutrients and oxygen from the atmosphere, however the same may continue within the water stream. But it is worse than before. Snow cover of ice on water body can effectively cut off light, plunging the waters into darkness. Hence photosynthesis stops but respiration continues. Thus, in shallow lakes, oxygen gets depleted, and due to lack of oxygen there is large scale death of fishes and other organisms. This condition is known as winterkill. Hence, option (c) is correct.
3. Consider the following statements regarding fine particulate matter (PM2.5):
1. They are visible to the naked eye and cause haze in the
traffic.
2. They can bypass the nose and throat and can easily enter the circulatory
system.
3. Their levels are most likely to be elevated on days with little or no wind or
air mixing.
How many statements given above are correct?
(a) Only one
(b) Only two
(c) All three
(d) None
Answer: (B)
Explanation: PM 2.5 is an atmospheric particulate matter of diameter of fewer than 2.5 micrometres, which is around 3 per cent the diameter of a human hair. It causes respiratory problems and reduces visibility. PM 2.5 particles can only be detected with the help of an electron microscope because they are so small. This prevents their dispersion in the atmosphere and increases concentration. Hence, statement 1 is incorrect.
The circulatory system, also called the cardiovascular system is an organ system that permits blood to circulate and transport nutrients (such as amino acids and electrolytes), oxygen, carbon dioxide, hormones, and blood cells to and from the cells in the body to provide nourishment. Due to their smaller size, the PM 2.5 particles can easily bypass the nose and throat and can easily enter the circulatory system. The particles can also lead to cause chronic diseases such as asthma, heart attack, bronchitis and other respiratory problems. Outdoor PM2.5 levels are most likely to be elevated on days with little or no wind or air mixing. Hence, statement 2 and 3 are correct.
4. Consider the following statements regarding Kelps:
1. Kelps are large brown algae seaweeds that can survive
freezing temperatures and long periods of darkness, and even grow under sea ice.
2. It is an important source of potash and iodine.
3. Kelp forests help protect coastlines by decreasing the power of waves during
storms and reducing coastal erosion.
How many statements given above are correct?
(a) Only one
(b) Only two
(c) All three
(d) None
Answer: (C)
Explanation: Kelps are large brown algae seaweedsthat make up the order Laminariales. There are about 30 different genera. Kelps have adapted to the severe conditions. These cool water species have special strategies to survive freezing temperatures and long periods of darkness, and even grow under sea ice. In regions with cold, nutrient-rich water, they can attain some of the highest rates of primary production of any natural ecosystem on Earth. Kelp forests also help protect coastlines by decreasing the power of waves during storms and reducing coastal erosion. Kelp forests throughout the world play an important role in coastal economies, supporting a broad range of tourism, recreational and commercial activities. Kelp is a coveted food source in many countries, full of potassium, iron, calcium, fibre and iodine. Hence, all statements are correct.
5. The primary productivity of the tropical rain forest is lower when compared to that of the temperate forests. This is because of:
(a) Low microbial activity in tropical regions
(b) Practice of slash and burn agriculture in many tropical regions
(c) Dense vegetation Cover in tropical rain forests
(d) Intense leaching of soil in tropical rain forests
Answer: (D)
Explanation: The soil is poor in nutrients and acidic due to frequent leaching by heavy rains. Frequent rains wash away the top soil leaving only certain mineral and organic remains. However, rainforests are also notable for replenishing the soil quickly with dead organic matter (e.g. leafs that fall from trees). Hence, option (d) is correct.
