Lesson 6.3.2a

6.3.2a Population size and interactions Quiz: OCR Biology, Unit 9

20 questions

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Lesson 6.3.2a, Population size and interactions: 20 multiple choice questions for the OCR Biology (H020), Unit 9: Ecosystems, written with Revision Ninja.

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The 20 questions

  1. What term defines the maximum stable population size an ecosystem can support?

    • Biotic potential
    • Climax community
    • Environmental resistance
    • Carrying capacity
  2. Which of these is a density-dependent factor affecting population size?

    • Disease
    • Volcanic eruption
    • Severe frost
    • Tsunami
  3. Which of these is a density-independent factor affecting population size?

    • Disease
    • Predation
    • Volcanic eruption
    • Interspecific competition
  4. What term describes competition between individuals of the same species?

    • Interspecific competition
    • Intraspecific competition
    • Competitive exclusion
    • Resource partitioning
  5. What term describes competition between individuals of different species?

    • Intraspecific competition
    • Interspecific competition
    • Competitive exclusion
    • Mutualism
  6. How do predator populations typically respond following a rise in prey numbers?

    • Remain completely constant
    • Rise after delay
    • Rise instantly
    • Fall immediately
  7. Which principle states that two species with identical niches cannot coexist indefinitely?

    • Carrying capacity
    • Competitive exclusion
    • Resource partitioning
    • Successional displacement
  8. In the logistic growth model, at what population size is the growth rate highest when the carrying capacity is 1000?

    • 500
    • 750
    • 250
    • 1000
  9. Following a sharp increase in predator numbers, what immediately happens to prey numbers?

    • They double
    • They decrease
    • They remain constant
    • They increase
  10. What happens to carrying capacity when a limiting nutrient is added to an ecosystem?

    • It remains unchanged
    • It increases
    • It drops to zero
    • It decreases
  11. What is the outcome when two species occupy exactly the same ecological niche?

    • Both species coexist
    • One species excluded
    • Increased biodiversity
    • Mutualistic symbiosis
  12. A population of 400 lives in an environment with a carrying capacity of 500. What percentage of carrying capacity is this?

    • 20%
    • 400%
    • 125%
    • 80%
  13. Which of these is a density-independent factor affecting an insect population?

    • Parasitism of individuals
    • Predation by birds
    • Severe frost
    • Competition for food
  14. Which term describes an interspecific interaction where both organisms benefit?

    • Predation
    • Parasitism
    • Mutualism
    • Commensalism
  15. In a predator-prey system, what increases directly after prey numbers rise?

    • Predator mortality rate
    • Prey birth rate
    • Interspecific competition
    • Predator birth rate
  16. What term describes the maximum stable population size an ecosystem can support?

    • Environmental resistance
    • Economic yield
    • Carrying capacity
    • Biotic potential
  17. A population of 200 has a birth rate of 0.3 per individual per year and a death rate of 0.1 per individual per year. What is the expected change in one year?

    • +20
    • +40
    • -40
    • +60
  18. What causes the time lag in predator population peaks behind prey peaks?

    • Rapid prey adaptation
    • Instantaneous birth rates
    • Time needed to reproduce
    • Immediate migration of predators
  19. A population of 800 has a carrying capacity of 1000 and a logistic intrinsic growth rate r = 0.2 per year. Using dN/dt = rN(1 - N/K), what is the expected change in one year?

    • 32
    • 160
    • 200
    • 8
  20. What allows two competing species to coexist long-term in the same habitat?

    • Identical niches
    • Intraspecific competition
    • Competitive exclusion
    • Niche differentiation

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