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Evolution and Biodiversity

Major Threats to Biodiversity Practice Questions

20 free Major Threats to Biodiversity practice questions for the Zoology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.

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Question 1 of 20 Medium

Which of the following is considered the greatest direct threat to global biodiversity?

  1. A Overpopulation of predators
  2. B Habitat destruction
  3. C Natural selection
  4. D Genetic recombination

Correct answer: Habitat destruction

Habitat destruction leads to loss of living space, food resources, and breeding grounds. It is the primary driver of species decline and extinction worldwide.

Question 2 of 20 Medium

Deforestation mainly threatens biodiversity by:

  1. A Steadily increasing overall soil fertility
  2. B Reducing habitat complexity
  3. C Enhancing species migration
  4. D Promoting speciation

Correct answer: Reducing habitat complexity

Deforestation simplifies habitats and removes niches needed by many species. This leads to population declines and loss of biodiversity.

Question 3 of 20 Medium

Invasive species threaten native biodiversity primarily because they:

  1. A Have low reproductive rates
  2. B Lack natural predators in the new habitat
  3. C Improve overall ecosystem productivity and health
  4. D Increase genetic diversity of natives

Correct answer: Lack natural predators in the new habitat

Invasive species often escape their natural predators and competitors. This allows them to spread rapidly and outcompete native species.

Question 4 of 20 Medium

Habitat fragmentation negatively affects biodiversity by:

  1. A Increasing overall gene flow
  2. B Reducing edge effects
  3. C Isolating populations
  4. D Creating new habitats

Correct answer: Isolating populations

Fragmentation divides populations into smaller, isolated groups. This reduces gene flow and increases the risk of inbreeding and extinction.

Question 5 of 20 Medium

Climate change threatens biodiversity mainly through:

  1. A Maintaining stable long-term temperature patterns
  2. B Altering habitats and species ranges
  3. C Reduction in mutation rates
  4. D Elimination of natural selection

Correct answer: Altering habitats and species ranges

Climate change alters temperature, rainfall, and seasonal cycles. These changes force species to shift ranges or face extinction.

Question 6 of 20 Medium

Which ecosystem is most vulnerable to rising global temperatures?

  1. A Grasslands
  2. B Coral reefs
  3. C Temperate forests
  4. D Deserts

Correct answer: Coral reefs

Coral reefs are highly sensitive to temperature changes. Rising sea temperatures cause coral bleaching and widespread reef mortality.

Question 7 of 20 Medium

The introduction of exotic predators to island ecosystems often results in:

  1. A Rapid adaptation of native species
  2. B Increased species richness
  3. C Extinction of native species
  4. D Stabilization of ecosystems

Correct answer: Extinction of native species

Island species often lack defenses against new predators. Introduced predators can quickly drive native species to extinction.

Question 8 of 20 Medium

Which human activity most directly accelerates habitat loss?

  1. A Urban and agricultural expansion
  2. B Sudden large-scale natural disasters
  3. C Seasonal migration
  4. D Ecological succession

Correct answer: Urban and agricultural expansion

Urban expansion and agricultural development convert natural habitats into human-dominated landscapes. This reduces available space for wildlife.

Question 9 of 20 Medium

Biological invasions reduce biodiversity mainly by:

  1. A Enhancing mutualism
  2. B Increasing speciation
  3. C Outcompeting native species
  4. D Promoting ecological balance

Correct answer: Outcompeting native species

Invasive species often outcompete native species for resources. This leads to population declines and loss of native biodiversity.

Question 10 of 20 Medium

Which of the following best explains range shifts in species due to climate change?

  1. A Species shift toward favorable conditions
  2. B Species lose all of their genetic variation entirely
  3. C Species stop reproducing
  4. D Species become invasive everywhere

Correct answer: Species shift toward favorable conditions

As climates change, species migrate to areas with suitable temperatures and resources. These shifts are an adaptive response to environmental change.

Question 11 of 20 Medium

Overexploitation interacts with habitat destruction by:

  1. A Reducing human impact
  2. B Speeding population recovery
  3. C Increasing extinction risk
  4. D Enhancing ecosystem resilience

Correct answer: Increasing extinction risk

When habitats are degraded, species become more vulnerable to overuse. Combined pressures greatly increase extinction risk.

Question 12 of 20 Medium

Which of the following is an example of an invasive species impact?

  1. A Cross-pollination of crops by managed honeybees
  2. B Native plants displaced by alien weeds
  3. C Seasonal migration of birds
  4. D Natural forest regeneration

Correct answer: Native plants displaced by alien weeds

Alien weeds often spread aggressively and displace native plant species. This reduces plant diversity and alters ecosystems.

Question 13 of 20 Medium

Climate-induced phenological changes refer to:

  1. A Permanent changes in population genetic structure
  2. B Shifts in timing of biological events
  3. C Loss of entire habitats
  4. D Increase in mutation rates

Correct answer: Shifts in timing of biological events

Phenological changes include altered timing of flowering, breeding, or migration. Climate change disrupts these biological schedules.

Question 14 of 20 Medium

Which species are most vulnerable to habitat destruction?

  1. A Generalist species
  2. B Cosmopolitan species
  3. C Endemic species
  4. D Invasive species

Correct answer: Endemic species

Endemic species have restricted geographic ranges. Habitat loss in those regions can quickly lead to extinction.

Question 15 of 20 Medium

Ocean acidification threatens biodiversity mainly by:

  1. A Increased fish reproduction and larval survival
  2. B Reduced calcium carbonate availability
  3. C Stabilizing marine food webs
  4. D Enhancing coral growth

Correct answer: Reduced calcium carbonate availability

Increased CO₂ lowers ocean pH, reducing calcium carbonate availability. This affects shell-forming organisms and coral reefs.

Question 16 of 20 Medium

Which factor makes invasive species difficult to control?

  1. A Slow growth rate
  2. B High ecological specialization
  3. C Rapid reproduction and spread
  4. D Dependence on native predators

Correct answer: Rapid reproduction and spread

Invasive species often reproduce rapidly and spread aggressively. This makes their management and eradication difficult.

Question 17 of 20 Medium

Loss of keystone species due to habitat destruction can lead to:

  1. A Minor ecological changes
  2. B Trophic cascades
  3. C Increased ecosystem stability
  4. D Enhanced biodiversity

Correct answer: Trophic cascades

Keystone species have a disproportionate effect on ecosystems. Their loss can trigger trophic cascades and major ecosystem disruption.

Question 18 of 20 Medium

Why does climate change increase extinction risk for polar species?

  1. A Expansion of suitable habitats poleward
  2. B Loss of ice-dependent habitats
  3. C Excessive rainfall
  4. D Increased genetic diversity

Correct answer: Loss of ice-dependent habitats

Polar species depend on ice-covered habitats. Melting ice reduces feeding and breeding grounds, increasing extinction risk.

Question 19 of 20 Medium

Which threat often acts synergistically with climate change to reduce biodiversity?

  1. A Habitat fragmentation
  2. B Directional natural selection
  3. C Genetic drift
  4. D Speciation

Correct answer: Habitat fragmentation

Fragmented habitats limit species movement needed to track climate shifts. This synergy greatly increases biodiversity loss.

Question 20 of 20 Medium

The combined effect of habitat loss, invasive species, and climate change results in:

  1. A Accelerated evolutionary adaptation in all species
  2. B Global biodiversity decline
  3. C Increased ecosystem resilience
  4. D Uniform species distribution

Correct answer: Global biodiversity decline

Multiple threats acting together intensify pressures on species and ecosystems. This leads to widespread global biodiversity decline.

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