Question 1

Which of the following ecosystems has the highest biodiversity on Earth?

Accepted Answer

Tropical rainforests have the highest biodiversity on Earth. Although they cover only about 7% of the Earth's land surface, they contain approximately 50% of all known species. The warm, wet climate and complex structure provide diverse habitats for millions of organisms.

Question 2

Which of the following is an example of a renewable source of energy?

Accepted Answer

Renewable energy sources are those that can be replenished naturally and are sustainable over long periods. Solar energy, wind energy, hydroelectric power, and biomass are all renewable sources. Non-renewable sources like coal, petroleum, and natural gas are finite and deplete over time.

Question 3

The process by which plants convert sunlight into chemical energy stored in glucose is called:

Accepted Answer

Photosynthesis is the biochemical process where plants, algae, and some bacteria use sunlight, water, and carbon dioxide to produce glucose (sugar) and oxygen. This process occurs primarily in the chloroplasts of plant cells and is fundamental to life on Earth as it forms the base of most food chains.

Question 4

Which of the following gases is primarily responsible for the greenhouse effect and is released through burning of fossil fuels?

Accepted Answer

Carbon dioxide (CO₂) is the primary greenhouse gas responsible for global warming. It is released when fossil fuels like coal, oil, and natural gas are burned for energy. While methane and nitrous oxide are also greenhouse gases, CO₂ is the most abundant and significant contributor to climate change.

Question 5

Which of the following gases is primarily responsible for the depletion of the ozone layer in the Earth's stratosphere?

Accepted Answer

Chlorofluorocarbons (CFCs) are the primary cause of ozone layer depletion. When CFCs reach the stratosphere, UV radiation breaks them down, releasing chlorine atoms that catalytically destroy ozone molecules. One chlorine atom can destroy up to 100,000 ozone molecules.

Question 6

Which of the following is a biodegradable waste material?

Accepted Answer

Biodegradable waste is organic material that can be decomposed by microorganisms (bacteria, fungi) into simpler substances. Paper is made from plant cellulose and can be broken down by microorganisms. Non-biodegradable materials like plastic, glass, and metals persist in the environment for hundreds of years.

Question 7

Which of the following is a biodegradable pollutant?

Accepted Answer

Sewage is a biodegradable pollutant because it consists of organic matter (human waste, food scraps, etc.) that can be decomposed by microorganisms. Biodegradable pollutants can be broken down naturally by biological processes.

Question 8

Which of the following is an example of a renewable energy source?

Accepted Answer

Solar energy is a renewable energy source because it is naturally replenished and does not deplete natural resources. The sun's energy is continuously available and can be harnessed through photovoltaic cells or solar thermal systems.

Question 9

Which of the following is the primary greenhouse gas responsible for climate change, and what is its approximate concentration in the atmosphere as of 2024?

Accepted Answer

Carbon dioxide (CO₂) is the primary anthropogenic greenhouse gas driving climate change. As of 2024, atmospheric CO₂ concentration has exceeded 420 ppm (parts per million), up from pre-industrial levels of ~280 ppm. This increase is primarily due to fossil fuel combustion and deforestation.

Question 10

What is the primary cause of acid rain in industrial regions?

Accepted Answer

Acid rain is primarily caused by sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) released from burning fossil fuels in factories and vehicles. These gases react with water vapor in the atmosphere to form sulfuric and nitric acids, which fall as acid rain.

Question 11

The layer of the atmosphere closest to the Earth's surface where weather occurs is called:

Accepted Answer

The troposphere is the lowest layer of Earth's atmosphere, extending from the surface to approximately 10-18 km altitude (varies with latitude). It contains about 80% of the atmosphere's mass and is where all weather phenomena occur, including clouds, rain, and wind. Temperature decreases with altitude in this layer.

Question 12

Which of the following is NOT a renewable energy source?

Accepted Answer

Non-renewable energy sources are finite resources that deplete over time and cannot be naturally replenished on human timescales. Coal, petroleum, and natural gas are fossil fuels formed from ancient organic matter over millions of years. Solar, wind, hydro, and geothermal energy are renewable because they are naturally replenished continuously.

Question 13

The 'carbon footprint' of a product or activity is primarily measured in terms of which unit?

Accepted Answer

Carbon footprint is measured in kilograms or tonnes of carbon dioxide equivalent (CO₂e), which includes all greenhouse gases converted to their CO₂ equivalent based on their Global Warming Potential (GWP) over a 100-year period.

Question 14

Which of the following gases is primarily responsible for the 'Greenhouse Effect' on Earth?

Accepted Answer

Carbon dioxide (CO2) is the primary greenhouse gas responsible for the greenhouse effect. It traps heat radiated from Earth's surface, preventing it from escaping into space. Other greenhouse gases include methane, nitrous oxide, and water vapour, but CO2 is considered the dominant driver of human-caused climate change.

Question 15

Which of the following is the correct definition of 'biodiversity hotspot' as per conservation biology?

Accepted Answer

A biodiversity hotspot is a biogeographic region with significant levels of biodiversity that is threatened by human activities. The term was coined by Norman Myers in 1988 and requires two criteria: high endemism (species found nowhere else) and significant habitat loss.

Question 16

The Montreal Protocol, signed in 1987, was primarily designed to address which environmental problem?

Accepted Answer

The Montreal Protocol is an international treaty designed to protect the ozone layer by phasing out the production and consumption of ozone-depleting substances (ODS), particularly chlorofluorocarbons (CFCs). It is considered one of the most successful environmental treaties.

Question 17

Which of the following ecosystems is characterized by the highest biodiversity per unit area and covers approximately 6–7% of Earth's land surface?

Accepted Answer

Tropical rainforests are the most biodiverse terrestrial ecosystems, containing approximately 50% of all species on Earth despite covering only 6–7% of land area. They are found near the equator in regions with high rainfall and warm temperatures year-round.

Question 18

The Montreal Protocol (1987) was primarily designed to address which environmental problem?

Accepted Answer

The Montreal Protocol is an international treaty designed to protect the ozone layer by phasing out ozone-depleting substances (ODS), particularly chlorofluorocarbons (CFCs). It is considered one of the most successful environmental agreements, with 99% of ozone-depleting substances phased out globally.

Question 19

Which of the following best describes the process of 'eutrophication' in aquatic ecosystems?

Accepted Answer

Eutrophication is the process by which a water body becomes overly enriched with nutrients (nitrogen and phosphorus), leading to excessive algal growth, oxygen depletion, and loss of aquatic biodiversity. It is primarily caused by agricultural runoff and sewage discharge.

Question 20

The process by which water changes from a liquid state to a gaseous state due to heat energy is called:

Accepted Answer

Evaporation is the phase transition process where liquid water transforms into water vapor (gas) when supplied with sufficient heat energy. This occurs at the water surface and is a key component of the hydrological cycle. The rate of evaporation increases with temperature, surface area, and air circulation.

SSC CGL Environment & Ecology

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Environment & Ecology — Practice Questions

60-Second Revision — Environment & Ecology