Part 3 – Importance of Biodiversity (25 MCQs)

Q1. Which of the following is NOT an importance of biodiversity?

a) Provides ecosystem services
b) Maintains ecological balance
c) Leads to habitat destruction
d) Source of food, medicine, and resources

Answer: c) Leads to habitat destruction

Explanation:

(a) Correct → Biodiversity ensures services.
(b) Correct → Maintains ecosystem balance.
(c) Correct answer → Habitat destruction reduces biodiversity, not its importance.
(d) Correct → Food, medicine come from biodiversity.

Q2. The Amazon rainforest is estimated to contribute about ______ of total oxygen in Earth’s atmosphere.

a) 10%
b) 20%
c) 30%
d) 40%

Answer: b) 20%

Explanation:

(a) Incorrect → Lower than actual.
(b) Correct → Amazon rainforest contributes ~20%.
(c) Incorrect → Too high.
(d) Incorrect → Not correct.

Q3. Which of the following is an ecosystem service provided by biodiversity?

a) Pollination
b) Carbon fixation
c) Climate regulation
d) All of the above

Answer: d) All of the above

Explanation:

(a) Partial → Pollination is one service.
(b) Partial → Carbon fixation = major service.
(c) Partial → Climate regulation via forests/oceans.
(d) Correct → All are biodiversity services.

Q4. Biodiversity contributes to human welfare because:

a) Provides food resources
b) Provides medicinal resources
c) Maintains ecological stability
d) All of these

Answer: d) All of these

Explanation:

(a) Correct → Source of cereals, pulses, fruits.
(b) Correct → ~25% drugs are plant-derived.
(c) Correct → Ensures balance and productivity.
(d) Correct → All are true.

Q5. Which of the following drugs is obtained from Rauwolfia plant?

a) Reserpine
b) Morphine
c) Quinine
d) Penicillin

Answer: a) Reserpine

Explanation:

(a) Correct → Rauwolfia serpentina = Reserpine.
(b) Incorrect → Morphine from Papaver (opium).
(c) Incorrect → Quinine from Cinchona bark.
(d) Incorrect → Penicillin from fungus Penicillium.

Q6. Which hypothesis compares species in an ecosystem to rivets in an airplane?

a) Red Queen Hypothesis
b) Rivet Popper Hypothesis
c) Competitive Exclusion Principle
d) Gaia Hypothesis

Answer: b) Rivet Popper Hypothesis

Explanation:

(a) Incorrect → Red Queen relates to evolution.
(b) Correct → Ehrlich’s Rivet Popper Hypothesis.
(c) Incorrect → Exclusion principle = ecology.
(d) Incorrect → Gaia = Earth as self-regulating.

Q7. Rivet Popper Hypothesis suggests that:

a) Loss of each species destabilizes ecosystem gradually
b) All species are equally redundant
c) Loss of one species never affects the ecosystem
d) Species richness is unimportant

Answer: a) Loss of each species destabilizes ecosystem gradually

Explanation:

(a) Correct → Like rivets in an airplane, gradual loss weakens system.
(b) Incorrect → Not all species are redundant.
(c) Incorrect → Species loss does affect ecosystem.
(d) Incorrect → Richness is very important.

Q8. Which scientist proposed the Rivet Popper Hypothesis?

a) Robert May
b) Paul Ehrlich
c) E.O. Wilson
d) Alexander von Humboldt

Answer: b) Paul Ehrlich

Explanation:

(a) Incorrect → Robert May = species estimate.
(b) Correct → Rivet Hypothesis by Paul Ehrlich.
(c) Incorrect → Wilson = biodiversity conservation.
(d) Incorrect → Humboldt = species–area.

Q9. Which of the following is an ethical reason for conserving biodiversity?

a) Future human benefits
b) Because other species have the right to exist
c) For medicines and food
d) For ecosystem services

Answer: b) Because other species have the right to exist

Explanation:

(a) Incorrect → This is utilitarian.
(b) Correct → Ethical reason = existence value.
(c) Incorrect → Economic reason.
(d) Incorrect → Ecological reason.

Q10. Biodiversity provides genetic resources for:

a) Plant breeding
b) Genetic engineering
c) Biotechnology
d) All of these

Answer: d) All of these

Explanation:

(a) Correct → Genes from wild plants used for crop improvement.
(b) Correct → Genes manipulated in genetic engineering.
(c) Correct → Biotechnology uses biodiversity.
(d) Correct → All are true.

Q11. Which of the following is NOT a direct benefit of biodiversity?

a) Food and fodder
b) Medicines
c) Fuelwood
d) Oxygen generation

Answer: d) Oxygen generation

Explanation:

(a) Correct → Food is a direct benefit.
(b) Correct → Medicines = direct benefit.
(c) Correct → Fuelwood = direct benefit.
(d) Correct answer → Oxygen generation is indirect service.

Q12. Which of the following is a consumptive use value of biodiversity?

a) Ecotourism
b) Timber
c) Recreation
d) Spiritual enrichment

Answer: b) Timber

Explanation:

(a) Incorrect → Ecotourism = non-consumptive.
(b) Correct → Timber = directly consumed resource.
(c) Incorrect → Recreation = non-consumptive.
(d) Incorrect → Spiritual = ethical/aesthetic.

Q13. Biodiversity plays a key role in ecosystem stability because:

a) Diverse ecosystems are more resilient
b) Species interactions reduce imbalance
c) Productivity increases with species richness
d) All of the above

Answer: d) All of the above

Explanation:

(a) Correct → Diversity = resilience to stress.
(b) Correct → More interactions stabilize ecosystems.
(c) Correct → Richness supports productivity.
(d) Correct → All valid.

Q14. Which of the following is an example of aesthetic value of biodiversity?

a) National parks and sanctuaries
b) Sacred groves
c) Recreational activities like birdwatching
d) All of these

Answer: d) All of these

Explanation:

(a) Correct → Parks are valued aesthetically.
(b) Correct → Sacred groves conserved for culture.
(c) Correct → Recreation adds aesthetic value.
(d) Correct → All apply.

Q15. Approximately what percentage of global oxygen is released by phytoplankton?

a) 10%
b) 30–40%
c) 50–70%
d) 90%

Answer: c) 50–70%

Explanation:

(a) Incorrect → Too low.
(b) Incorrect → Still lower than actual.
(c) Correct → Phytoplankton produce 50–70% of O₂.
(d) Incorrect → 90% is an overestimate.

Q16. Which of the following is NOT an ecosystem service of biodiversity?

a) Climate regulation
b) Nutrient cycling
c) Industrialization
d) Soil formation

Answer: c) Industrialization

Explanation:

(a) Correct → Biodiversity regulates climate.
(b) Correct → Nutrient cycling is a service.
(c) Correct answer → Industrialization is human-driven.
(d) Correct → Soil formation is ecosystem service.

Q17. Which crop was improved by resistance genes taken from wild relatives in India?

a) Rice
b) Wheat
c) Maize
d) Sugarcane

Answer: a) Rice

Explanation:

(a) Correct → Wild rice genes used for pest resistance.
(b) Incorrect → Wheat also improved but not cited in NCERT.
(c) Incorrect → Not maize.
(d) Incorrect → Not sugarcane.

Q18. Which of the following is an example of pollination service by biodiversity?

a) Honey bee pollinating crops
b) Bat pollinating flowers
c) Wind dispersing pollen
d) Both a and b

Answer: d) Both a and b

Explanation:

(a) Correct → Honey bee pollination is vital.
(b) Correct → Bats pollinate night-blooming plants.
(c) Incorrect → Wind pollination is abiotic.
(d) Correct → Both a & b are biotic services.

Q19. Biodiversity increases ecosystem productivity because:

a) More species = more ecological niches filled
b) All species perform the same role
c) Less interaction among species
d) Competition reduces resources

Answer: a) More species = more ecological niches filled

Explanation:

(a) Correct → Functional complementarity boosts productivity.
(b) Incorrect → Species are not redundant.
(c) Incorrect → Interactions are important.
(d) Incorrect → Competition alone doesn’t explain productivity.

Q20. Which of the following is an example of indirect use value of biodiversity?

a) Fruits
b) Firewood
c) Climate regulation by forests
d) Medicinal plants

Answer: c) Climate regulation by forests

Explanation:

(a) Incorrect → Fruits = direct consumptive.
(b) Incorrect → Firewood = direct consumptive.
(c) Correct → Regulation = indirect service.
(d) Incorrect → Medicines = direct benefit.

Q21. The role of biodiversity in controlling pests is called:

a) Biological control
b) Genetic engineering
c) Bioremediation
d) Biomagnification

Answer: a) Biological control

Explanation:

(a) Correct → Predators, parasites keep pests in check.
(b) Incorrect → Engineering modifies genes.
(c) Incorrect → Remediation cleans environment.
(d) Incorrect → Biomagnification is toxin accumulation.

Q22. Which of the following values of biodiversity relates to recreational benefits?

a) Direct consumptive
b) Indirect use
c) Ethical value
d) Aesthetic value

Answer: d) Aesthetic value

Explanation:

(a) Incorrect → Consumptive = food, fuel.
(b) Incorrect → Indirect = climate, nutrient cycling.
(c) Incorrect → Ethical = species right to exist.
(d) Correct → Recreation = aesthetic.

Q23. Which of the following ecosystem services is most directly linked to biodiversity?

a) Soil erosion
b) Pollination
c) Mining
d) Urbanization

Answer: b) Pollination

Explanation:

(a) Incorrect → Erosion is damage, not service.
(b) Correct → Pollination is direct service of biodiversity.
(c) Incorrect → Mining = destructive.
(d) Incorrect → Urbanization reduces biodiversity.

Q24. Which of the following is an option value of biodiversity?

a) Ecotourism
b) Future potential uses like new medicines
c) Ethical obligation to conserve
d) Oxygen production

Answer: b) Future potential uses like new medicines

Explanation:

(a) Incorrect → Ecotourism = aesthetic.
(b) Correct → Option value = potential future use.
(c) Incorrect → Ethical value = right to exist.
(d) Incorrect → Oxygen production = ecosystem service.

Q25. Which of the following explains biodiversity’s role in ecosystem stability?

a) Monocultures are more productive
b) More diversity = less resilience
c) More diversity = more stable ecosystem
d) Stability is unrelated to diversity

Answer: c) More diversity = more stable ecosystem

Explanation:

(a) Incorrect → Monocultures are unstable.
(b) Incorrect → Diversity increases resilience.
(c) Correct → Higher diversity → greater stability.
(d) Incorrect → Stability strongly depends on diversity.

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Part 3 – Importance of Biodiversity (25 MCQs)