MCQs on Biosphere – Geography
Q1. The biosphere is defined as:
a) The part of Earth where life exists
b) The part of Earth where only plants exist
c) The part of Earth where only animals exist
d) The part of Earth where only humans exist
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Correct Answer: a) The part of Earth where life exists
Explanation: The biosphere is the region on, above, and below the Earth’s surface where life exists, encompassing all living organisms and their environments.
Q2. Which of the following is NOT a component of the biosphere?
a) Atmosphere
b) Hydrosphere
c) Lithosphere
d) Stratosphere
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Correct Answer: d) Stratosphere
Explanation: The biosphere is a combination of the lithosphere (land), atmosphere (air), and hydrosphere (water) where life exists. The stratosphere is a layer of Earth’s atmosphere, not a component of the biosphere.
Q3. The term “ecosystem” refers to:
a) A community of living organisms and their physical environment
b) A group of similar species living in the same area
c) The study of the Earth’s surface
d) The study of the Earth’s atmosphere
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Correct Answer: a) A community of living organisms and their physical environment
Explanation: An ecosystem is a geographical region where plants, animals, and other species interact and coexist with their physical environment, including both biotic (living) and abiotic (nonliving) components.
Q4. Which of the following is an example of a terrestrial ecosystem?
a) Ocean
b) River
c) Forest
d) Coral reef
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Correct Answer: c) Forest
Explanation: A terrestrial ecosystem is an ecosystem that exists on land) Forests are an example of terrestrial ecosystems, while oceans, rivers, and coral reefs are examples of aquatic ecosystems.
Q5. Which of the following is an example of an aquatic ecosystem?
a) Desert
b) Mountain
c) Wetland
d) Grassland
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Correct Answer: c) Wetland
Explanation: An aquatic ecosystem is an ecosystem that exists in water. Wetlands are an example of aquatic ecosystems, while deserts, mountains, and grasslands are examples of terrestrial ecosystems.
Q6. The primary source of energy for the biosphere is:
a) Wind
b) Geothermal energy
c) Solar energy
d) Fossil fuels
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Correct Answer: c) Solar energy
Explanation: The biosphere is an open system that uses photosynthesis to absorb solar energy at a rate of about 130 Terawatts per year, making solar energy the primary source of energy for the biosphere.
Q7. The process by which green plants convert sunlight into chemical energy is called:
a) Respiration
b) Photosynthesis
c) Decomposition
d) Fermentation
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Correct Answer: b) Photosynthesis
Explanation: Photosynthesis is the process by which green plants, algae, and some bacteria convert sunlight, carbon dioxide, and water into glucose (chemical energy) and oxygen.
Q8. Which of the following gases is most abundant in the Earth’s atmosphere?
a) Oxygen
b) Nitrogen
c) Carbon dioxide
d) Methane
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Correct Answer: b) Nitrogen
Explanation: Nitrogen is the most abundant gas in Earth’s atmosphere, making up about 78% of its volume. Oxygen is the second most abundant gas, accounting for about 21% of the atmosphere.
Q9. The process by which water evaporates from the Earth’s surface and returns to the atmosphere is called:
a) Transpiration
b) Condensation
c) Precipitation
d) Evaporation
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Correct Answer: d) Evaporation
Explanation: Evaporation is the process by which water changes from a liquid state to a gaseous state (water vapour) and enters the atmosphere.
Q10. The process by which water is released by plants into the atmosphere is called:
a) Transpiration
b) Condensation
c) Precipitation
d) Evaporation
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Correct Answer: a) Transpiration
Explanation: Transpiration is the process by which plants release water vapor into the atmosphere through small openings called stomata, usually found on the underside of leaves.
Q11. Which of the following is a biotic component of an ecosystem?
a) Soil
b) Water
c) Air
d) Plants
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Correct Answer: d) Plants
Explanation: Biotic components of an ecosystem are the living organisms, such as plants, animals, and microorganisms.
Q12. Which of the following is an abiotic component of an ecosystem?
a) Bacteria
b) Fungi
c) Temperature
d) Animals
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Correct Answer: c) Temperature
Explanation: Abiotic components of an ecosystem are the nonliving factors, such as temperature, soil, water, and air.
Q13. The process by which organisms break down complex organic compounds into simpler ones is called:
a) Photosynthesis
b) Respiration
c) Decomposition
d) Fermentation
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Correct Answer: c) Decomposition
Explanation: Decomposition is the process by which decomposers, such as bacteria and fungi, break down dead organic matter into simpler compounds, recycling nutrients back into the ecosystem.
Q14. The process by which nitrogen gas in the atmosphere is converted into ammonia is called:
a) Nitrogen fixation
b) Nitrification
c) Denitrification
d) Ammonification
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Correct Answer: a) Nitrogen fixation
Explanation: Nitrogen fixation is the process by which certain bacteria and archaea convert atmospheric nitrogen gas (N2) into ammonia (NH3), making it available for plants to use.
Q15. The process by which ammonia is converted into nitrite and then nitrate is called:
a) Nitrogen fixation
b) Nitrification
c) Denitrification
d) Ammonification
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Correct Answer: b) Nitrification
Explanation: Nitrification is a two-step process in which ammonia (NH3) is first converted into nitrite (NO2-) by ammonia-oxidizing bacteria, and then nitrite is converted into nitrate (NO3-) by nitrite-oxidizing bacteria.
Q16. The process by which nitrate is converted back into nitrogen gas is called:
a) Nitrogen fixation
b) Nitrification
c) Denitrification
d) Ammonification
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Correct Answer: c) Denitrification
Explanation: Denitrification is the process by which certain bacteria convert nitrate (NO3-) back into nitrogen gas (N2), returning it to the atmosphere and completing the nitrogen cycle.
Q17. Which of the following is a major cause of biodiversity loss?
a) Habitat destruction
b) Overexploitation
c) Pollution
d) All of the above
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Correct Answer: d) All of the above
Explanation: Biodiversity loss can be caused by habitat destruction, overexploitation of resources, pollution, climate change, and other factors.
Q18. The term “keystone species” refers to:
a) A species that has a disproportionately large effect on its environment relative to its abundance
b) A species that is found only in a specific geographic area
c) A species that is at the top of the food chain
d) A species that is at risk of extinction
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Correct Answer: a) A species that has a disproportionately large effect on its environment relative to its abundance
Explanation: A keystone species is a species that plays a critical role in maintaining the structure and function of an ecosystem, despite its relatively low abundance. The removal of a keystone species can lead to significant changes in the ecosystem, such as the loss of other species or a shift in the ecosystem’s overall structure.
Q19. Which of the following is an example of a renewable resource?
a) Coal
b) Oil
c) Solar energy
d) Natural gas
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Correct Answer: c) Solar energy
Explanation: Renewable resources are natural resources that can be replenished over time, either through natural processes or human intervention. Solar energy is a renewable resource because it is derived from the sun, which is a virtually inexhaustible source of energy. Coal, oil, and natural gas are non-renewable resources because they are finite and cannot be replenished on a human timescale.
Q20. The concept of sustainable development aims to:
a) Maximize economic growth at all costs
b) Preserve the environment for future generations
c) Balance economic growth with environmental protection
d) Focus solely on environmental protection
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Correct Answer: c) Balance economic growth with environmental protection
Explanation: Sustainable development is a concept that seeks to balance economic growth and development with the need to protect and preserve the environment for future generations. This approach recognizes the importance of meeting the needs of the present without compromising the ability of future generations to meet their own needs.