Why species loss destabilises an ecosystem — NEET & JEE Questions

Question 1 · difficulty L1 · recall

What does the rivet popper hypothesis illustrate about biodiversity loss?

• A. Species loss can progressively weaken ecosystem function
• B. Every species can be removed because ecological roles are completely interchangeable
• C. Species loss always improves stability
• D. Only large animals affect ecosystems

Question 2 · difficulty L2 · understanding

Which feature is generally associated with a more stable ecosystem?

• A. Large year-to-year fluctuations in productivity despite otherwise unchanged conditions
• B. Lower variation in productivity between years
• C. Complete absence of consumers
• D. No response to environmental change

Question 3 · difficulty L2 · understanding

Why can loss of biodiversity reduce ecosystem stability?

• A. Fewer species can reduce functional redundancy and resilience to disturbance
• B. Every species performs exactly the same role
• C. Species richness is unrelated to ecosystem processes
• D. Removing species always increases productivity

Question 4 · difficulty L2 · understanding

Paul Ehrlich's rivet-popper hypothesis compares species in an ecosystem to

• A. rivets in an airplane whose progressive loss can eventually cause system failure
• B. fuel molecules that are never structurally important
• C. identical passengers with no effect on the aircraft
• D. genes in a single chromosome only

Question 5 · difficulty L3 · application

A plant community loses several pollinator species, and seed production then falls in many plants. What does this best demonstrate?

• A. Pollinators are unrelated to plant reproduction
• B. Only plants are affected by biodiversity loss
• C. Species loss can propagate through ecological interactions
• D. Ecosystem species function independently, so losses cannot affect interacting partners

Question 6 · difficulty L3 · application

An ecosystem loses several pollinator species that served overlapping plant species. Which outcome is plausible?

• A. Pollination can become less reliable, especially under environmental change
• B. Plant reproduction must improve
• C. No ecosystem process can change
• D. All plants become wind-pollinated immediately

Question 7 · difficulty L3 · application

Long-term grassland experiments show that more diverse plots can have more stable productivity through time. What does this support?

• A. Biodiversity can contribute to ecosystem stability
• B. Species richness always lowers productivity
• C. Stability is independent of community composition
• D. Only abiotic factors matter

Question 8 · difficulty L3 · application

Why might losing a top predator destabilise a food web more than losing a species with a highly redundant role?

• A. The predator may exert strong cascading effects across trophic levels
• B. All species have exactly equal ecological effects
• C. Top predators never influence prey abundance
• D. Redundant species are always keystone species

Question 9 · difficulty L4 · application

A diverse community contains several species that perform similar nutrient-cycling functions but respond differently to drought. Why can this increase stability?

• A. If drought suppresses some species, others may continue the function
• B. All species must respond identically
• C. Redundancy eliminates natural selection
• D. Drought cannot affect ecosystem processes

Question 10 · difficulty L4 · application

Which observation would most strongly support the claim that species loss can destabilise an ecosystem?

• A. Progressive species removals are followed by greater fluctuations in productivity and poorer recovery after disturbance
• B. Species removals have no measurable effects across all functions and conditions
• C. Productivity becomes perfectly constant after every removal
• D. No interactions occur among species