Nature’s Treasures Part 3: MCQs (Q51–Q75)
Part III — Questions 51–75
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Which gas contributes most to the greenhouse effect among the following?
A. Oxygen
B. Nitrogen
C. Carbon dioxide
D. Argon
Correct Answer: C — Carbon dioxide
Explanation:
A: Oxygen does not significantly trap heat.
B: Nitrogen is inert for greenhouse effect.
C: Correct — CO₂ is a major greenhouse gas increasing global warming.
D: Argon is a noble gas with minimal greenhouse role. -
Which of the following is NOT a function of forests?
A. Source of medicinal plants
B. Control of climate and rainfall patterns
C. Production of coal in short time
D. Habitat for many species
Correct Answer: C — Production of coal in short time
Explanation:
A: Forests are sources of many medicinal plants.
B: Forests influence climate and rainfall through transpiration.
C: Correct — coal forms over millions of years, not quickly by forests.
D: Forests provide habitats — true. -
Which of the following is a step to prevent soil erosion on agricultural land?
A. Clear cutting near rivers
B. Overgrazing by livestock
C. Terracing on slopes
D. Removing all vegetation
Correct Answer: C — Terracing on slopes
Explanation:
A: Clear cutting increases erosion.
B: Overgrazing damages plant cover and worsens erosion.
C: Correct — terracing reduces slope steepness and run-off.
D: Removing vegetation exposes soil to erosion. -
Which of the following is obtained from coal?
A. Oxygen
B. Electricity (when coal is burned in power plants)
C. Freshwater
D. Rubber
Correct Answer: B — Electricity (when coal is burned in power plants)
Explanation:
A: Burning coal consumes oxygen but doesn’t produce it.
B: Correct — coal combustion generates heat used to produce electricity.
C: Coal isn’t a source of freshwater.
D: Rubber is plant-derived or synthetic; unrelated. -
Which of the following is an effect of excessive use of chemical fertilizers?
A. Increased soil fertility forever
B. Soil and water pollution
C. Immediate increase in wildlife population
D. Better taste of all crops always
Correct Answer: B — Soil and water pollution
Explanation:
A: Over time, excessive chemicals can reduce soil health, so not forever.
B: Correct — runoff causes eutrophication and contaminates groundwater.
C: Chemicals often harm wildlife rather than boost their numbers.
D: Chemical use does not guarantee improved taste. -
What is the main reason for extinction of many species?
A. Increase in forest cover
B. Habitat destruction and human activities
C. Creation of national parks
D. Planting more trees
Correct Answer: B — Habitat destruction and human activities
Explanation:
A: Increased forest cover usually helps species.
B: Correct — loss of habitat, pollution and hunting drive extinctions.
C: Parks help conserve species.
D: Planting trees generally aids biodiversity. -
Which of the following statements is true about recycling?
A. Recycling increases waste volume
B. Recycling converts waste materials into reusable products
C. Recycling always uses more energy than producing new items
D. Recycling only works for organic waste
Correct Answer: B — Recycling converts waste materials into reusable products
Explanation:
A: Recycling reduces the amount sent to landfills.
B: Correct — it transforms waste into new materials, conserving resources.
C: Often recycling uses less energy than producing from raw materials.
D: Many materials (paper, glass, metal, plastic) can be recycled; not only organic waste. -
Which of these processes adds salts and minerals to soil making it poor for farming?
A. Leaching (washing away nutrients)
B. Salinization
C. Mulching
D. Composting
Correct Answer: B — Salinization
Explanation:
A: Leaching removes nutrients, not add salts.
B: Correct — salinization is accumulation of salts in soil, harming crops.
C: Mulching helps retain moisture and improves soil.
D: Composting adds organic matter and nutrients, improving soil. -
Which of the following is a fuel that is gaseous at room temperature?
A. Coal
B. Natural gas (methane)
C. Wood
D. Petroleum (liquid form)
Correct Answer: B — Natural gas (methane)
Explanation:
A: Coal is solid.
B: Correct — natural gas (mainly methane) is gaseous at room temperature.
C: Wood is solid biomass.
D: Petroleum is typically liquid (crude oil) at room temperature. -
Which of the following ____ helps farmers conserve soil moisture and prevent erosion?
A. Over-irrigation
B. Mulching (covering soil with organic matter)
C. Removing crop residues
D. Burning fields after harvest
Correct Answer: B — Mulching (covering soil with organic matter)
Explanation:
A: Over-irrigation can lead to erosion and salinity problems.
B: Correct — mulch reduces evaporation, protects soil, and adds organic matter.
C: Leaving residues helps protect soil; removing them increases erosion.
D: Burning destroys organic matter and harms the soil. -
Which of the following is a method to minimize waste at the source?
A. Buy excessive packaging items
B. Use reusable containers and buy in bulk
C. Throw recyclable waste in the trash
D. Use many single-use items daily
Correct Answer: B — Use reusable containers and buy in bulk
Explanation:
A: More packaging increases waste.
B: Correct — reusable containers and bulk buying reduce packaging waste.
C: That wastes recyclables.
D: Single-use items increase waste generation. -
Which of these is the main raw material for making bricks?
A. Sand only
B. Clay (soil rich in fine particles)
C. Metal ore
D. Wood
Correct Answer: B — Clay (soil rich in fine particles)
Explanation:
A: Sand may be used in mortar but bricks are primarily made of clay.
B: Correct — clay is moulded and fired to make bricks.
C: Metal ore is not used for bricks.
D: Wood is not a brick material. -
Which of these practices helps protect wildlife?
A. Cutting trees in protected areas
B. Introducing invasive species
C. Creating wildlife corridors
D. Polluting wetlands
Correct Answer: C — Creating wildlife corridors
Explanation:
A: Cutting trees harms wildlife habitats.
B: Invasive species often harm native wildlife.
C: Correct — corridors connect habitat patches allowing safe movement of animals.
D: Polluting wetlands destroys habitats and species. -
Which of the following is produced by plants and used by humans as fibre?
A. Coal
B. Cotton
C. Iron
D. Sand
Correct Answer: B — Cotton
Explanation:
A: Coal is a fossil fuel, not a fibre.
B: Correct — cotton is plant fibre used in textiles.
C: Iron is a metal, not a fibre.
D: Sand is mineral, not fibre. -
Which is the largest reservoir of freshwater on Earth (in frozen form)?
A. Rivers
B. Lakes
C. Glaciers and polar ice caps
D. Groundwater
Correct Answer: C — Glaciers and polar ice caps
Explanation:
A: Rivers contain a small fraction of freshwater.
B: Lakes hold more than rivers but less than ice.
C: Correct — most freshwater is locked in glaciers and ice caps.
D: Groundwater is a major store but less than polar ice. -
Which of the following is NOT a renewable source of energy?
A. Biomass (wood, crop waste)
B. Solar energy
C. Coal
D. Wind energy
Correct Answer: C — Coal
Explanation:
A: Biomass can be renewable if managed sustainably.
B: Solar is renewable.
C: Correct — coal is a non-renewable fossil fuel.
D: Wind is renewable. -
Which of the following organisms break down dead organic matter and return nutrients to soil?
A. Predator animals
B. Decomposers (bacteria and fungi)
C. Producer plants
D. Pollinators
Correct Answer: B — Decomposers (bacteria and fungi)
Explanation:
A: Predators consume live prey, not primarily decomposing matter.
B: Correct — decomposers break down dead matter into nutrients (humus).
C: Producers make food via photosynthesis but don’t decompose dead matter.
D: Pollinators help plant reproduction, not decomposition. -
Which practice helps reduce soil salinity in irrigated fields?
A. Poor drainage and over-irrigation
B. Proper drainage and controlled irrigation
C. Using only saline water for irrigation
D. Planting salt-loving invasive species everywhere
Correct Answer: B — Proper drainage and controlled irrigation
Explanation:
A: These worsen salinity.
B: Correct — managing water prevents salt buildup and leaching salts away.
C: Saline water increases salinity.
D: Invasive species can harm native ecosystems and are not a general solution. -
What is the main harmful effect of oil spills in oceans?
A. Increased fish populations
B. Killing marine life and polluting habitats
C. Conversion of oil into food for fishes immediately
D. Adding oxygen to water
Correct Answer: B — Killing marine life and polluting habitats
Explanation:
A: Oil spills harm, not boost, fish populations.
B: Correct — oil coats animals, damages gills and habitats, and poisons food chains.
C: Oil is toxic and not a food source.
D: Oil reduces oxygen transfer and harms water quality. -
Which of the following materials is commonly reused to make new paper?
A. Metal cans
B. Waste paper
C. Plastic bottles
D. Glass bottles
Correct Answer: B — Waste paper
Explanation:
A: Metal cans are recycled into metal products.
B: Correct — used paper is recycled into new paper sheets.
C: Plastic is recyclable but not for paper.
D: Glass is recyclable separately. -
Which of these human actions increases flood risk in towns and cities?
A. Maintaining parks and wetlands
B. Building permeable pavements
C. Paving over natural drains and wetlands
D. Planting trees in urban areas
Correct Answer: C — Paving over natural drains and wetlands
Explanation:
A: Parks and wetlands absorb water, reducing floods.
B: Permeable pavements allow infiltration.
C: Correct — paving prevents infiltration and increases run-off and flood risk.
D: Urban trees reduce run-off and improve drainage. -
Which of the following is true about national parks?
A. They allow unrestricted hunting
B. They are areas set aside for industrial development
C. They protect plants and animals and their habitats
D. They are for building new cities
Correct Answer: C — They protect plants and animals and their habitats
Explanation:
A: Hunting is generally prohibited in national parks.
B: Industrial development is restricted in national parks.
C: Correct — parks conserve biodiversity and ecosystems.
D: Building cities would harm the park’s purpose. -
Which of the following resources is most directly affected by oil drilling and extraction?
A. Wind energy
B. Marine and terrestrial habitats (through spills and land use change)
C. Solar radiation
D. Air oxygen levels instantly increased
Correct Answer: B — Marine and terrestrial habitats (through spills and land use change)
Explanation:
A: Wind energy is unrelated to oil extraction impacts.
B: Correct — oil activities can damage habitats via spills and infrastructure.
C: Solar radiation is unaffected by drilling.
D: Oil extraction does not increase air oxygen. -
Which of the following is a product of photosynthesis that is essential for animals?
A. Carbon dioxide
B. Water
C. Oxygen
D. Nitrogen
Correct Answer: C — Oxygen
Explanation:
A: CO₂ is consumed by plants during photosynthesis.
B: Water is used in photosynthesis but not the primary product animals need.
C: Correct — oxygen produced by plants is essential for animals’ respiration.
D: Nitrogen is not produced by photosynthesis. -
Which of the following is a consequence of overfishing?
A. Increase in fish population balance
B. Decline of fish species and disruption of food chains
C. Improvement of marine biodiversity
D. Cleaner oceans always
Correct Answer: B — Decline of fish species and disruption of food chains
Explanation:
A: Overfishing reduces populations, not balance.
B: Correct — removing too many fish disrupts ecological balance and can cause declines.
C: It reduces, not improves, biodiversity.
D: Overfishing does not clean oceans; it harms them.