Q71. Global warming is best defined as:
Environmental and Ecological Changes and Impact Assessment: RAS Prelims MCQs
168 RAS Prelims MCQs on environmental and ecological changes and impact assessment cover ecosystem concepts, pollution, climate and environmental law. Ecotones, decomposers, primary productivity, secondary pollutants, the greenhouse effect, the EIA Notification 2006, the Environment (Protection) Act 1986 and the Aravalli mining ban are asked as definitions, laws and statements.
Practice questions based on the RPSC RAS Prelims syllabus. They follow the exam pattern but are not past-paper questions.
Showing 71–80 of 168 questions
Q72. Albedo effect is crucial in global warming discussions. What happens when Arctic sea ice melts?
Explanation
The reflectivity of the Earth’s surface plays a critical role in the global climate. Bright surfaces like ice reflect most of the incoming sunlight back into space. When this ice melts and is replaced by dark ocean water, the amount of energy absorbed by the planet increases. This feedback loop accelerates the warming process, leading to even more ice loss and higher temperatures.
Q73. Identify the incorrect statement concerning greenhouse gases.
Explanation
While human activities are major sources of various greenhouse gases, many also occur naturally. For example, a potent heat-trapping gas is produced not only by industrial processes but also through biological decomposition in wetlands and the digestive systems of certain animals. Understanding both the natural and anthropogenic sources of these gases is essential for developing effective strategies to manage their atmospheric concentrations.
Q74. The melting of permafrost in the Arctic is a major concern because it threatens to release massive amounts of which potent greenhouse gas?
Explanation
In the cold regions of the north, the ground remains frozen throughout the year, trapping large amounts of ancient organic matter. As temperatures rise and this frozen layer thaws, microbes begin to break down the material. This biological process releases a powerful greenhouse gas into the atmosphere. This release is a major concern because it can trigger further warming and even more rapid melting.
Q75. How do higher global temperatures directly affect sea levels?
Explanation
Rising global temperatures cause sea levels to increase through two primary physical processes. First, the heat causes glaciers and polar ice sheets to melt, adding more liquid water to the oceans. Second, as the ocean water itself warms up, it physically expands and takes up more space. Together, these factors lead to a steady rise in the average height of the world’s seas.
Q76. Given below are two statements, one is labelled as Assertion (A) and the other as Reason (R):
Assertion (A): Carbon dioxide is the most significant anthropogenic greenhouse gas despite having a lower global warming potential than methane.
Reason (R): Carbon dioxide is present in the atmosphere in much larger concentrations and persists for a longer duration than methane.
Assertion (A): Carbon dioxide is the most significant anthropogenic greenhouse gas despite having a lower global warming potential than methane.
Reason (R): Carbon dioxide is present in the atmosphere in much larger concentrations and persists for a longer duration than methane.
Explanation
While some gases are more potent at trapping heat than others, their total impact depends on their concentration and how long they remain in the air. Carbon dioxide is released in massive quantities from burning fossil fuels and stays in the atmosphere for centuries. Therefore, even though a molecule of methane is more effective at absorbing radiation, the sheer volume of carbon dioxide makes it the primary driver.
Q77. The ozone layer is predominantly found in which layer of the Earth’s atmosphere?
Explanation
The Earth’s atmosphere is divided into several distinct layers based on temperature and composition. A specific region containing a high concentration of a three-atom oxygen molecule is located above the lowest layer where weather occurs. This protective shield sits between approximately fifteen and thirty-five kilometers above the surface. Its presence is vital for life because it filters out most of the sun’s harmful ultraviolet radiation.
Q78. What is the primary function of the stratospheric ozone layer?
Explanation
High in the atmosphere, a thin layer of gas performs a critical role in protecting all living things on Earth. It acts as a natural filter, absorbing the majority of the high-energy ultraviolet radiation from the sun. Without this shield, this radiation would reach the surface in amounts that could cause widespread damage to DNA, increase skin cancer rates, and harm many different types of ecosystems.
Q79. Chlorofluorocarbons (CFCs) cause ozone depletion primarily because:
Explanation
Certain synthetic chemicals were once commonly used in cooling systems and aerosol cans. When these stable compounds reach the upper atmosphere, they are broken down by intense sunlight. This reaction releases a highly reactive element that can destroy thousands of ozone molecules through a series of chemical cycles. This process leads to a significant thinning of the protective layer that filters ultraviolet radiation.
Q80. The "ozone hole" refers to a region of exceptionally depleted ozone primarily observed over:
Explanation
Every year, a dramatic thinning of the ozone layer occurs over a specific polar region during the late winter and spring. This phenomenon is driven by unique atmospheric conditions and the presence of man-made chemicals. The extreme cold in the area leads to the formation of special clouds that provide a surface for the chemical reactions that destroy ozone molecules, resulting in the well-known depletion zone.Answer key for these questions
| Q | Correct answer |
|---|---|
| 71 | (d) Long-term heating of climate system |
| 72 | (a) Albedo decreases, increasing absorption |
| 73 | (b) Methane is exclusively produced by industrial activities. |
| 74 | (b) Methane |
| 75 | (a) Via thermal expansion and ice melting |
| 76 | (a) Both A and R are true and R is the correct explanation of A. |
| 77 | (c) Stratosphere |
| 78 | (b) It absorbs harmful solar UV radiation |
| 79 | (d) They release ozone-destroying chlorine |
| 80 | (a) Antarctica |
Key facts from Environmental and Ecological Changes and Impact Assessment
- An ecosystem is made of interacting organisms and their physical environment; an ecotone is a zone of transition between ecosystems.
- Saprotrophs convert complex organic matter into simple substances; gross primary productivity is the rate at which producers create organic matter.
- Plants release water vapour through transpiration.
- Ground-level ozone is a secondary pollutant; CO, SO₂ and PM10 are primary pollutants.
- The greenhouse effect is the trapping of heat by atmospheric gases.
- Category B2 projects are exempt from public consultation under the EIA Notification 2006; the Supreme Court banned mining in the Aravalli range in Haryana and Rajasthan.
Frequently asked questions
How many RAS Prelims practice MCQs are there on Environmental and Ecological Changes and Impact Assessment?
This page has 168 practice MCQs on Environmental and Ecological Changes and Impact Assessment (Health, Environment and Agriculture). Each has the correct answer, and most have an explanation.
What is a secondary pollutant?
A pollutant that is not emitted directly but forms in the air from primary pollutants. Ground-level ozone is the standard example, formed when nitrogen oxides and volatile organic compounds react in sunlight.
What is an ecotone?
A zone of transition between two different ecosystems, such as the area between a forest and a grassland. It often has more species than either neighbour because it has species of both.
Which projects are exempt from public consultation under EIA 2006?
Category B2 projects, which have less environmental impact. Category A and B1 projects need public consultation as part of the clearance process, which is the main way local people are heard.