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Biology 30 · Worksheets

Populations · Set A

Ten questions of mixed difficulty, covering Populations. Print it, or work through it on screen — the answer key starts on its own page.

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Populations · Set A

Biology 30 · maddyhelps.com

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Circle the best answer for each question. Show your work in the space provided.

  1. A tapeworm living in a human intestine is an example of:

    1. a) mutualism
    2. b) commensalism
    3. c) parasitism
    4. d) competition

  2. 16% of a population shows a recessive trait. What is the frequency of the recessive allele, q?

    1. a) 0.32
    2. b) 0.16
    3. c) 0.4
    4. d) 0.84

  3. Which situation would most likely disturb Hardy–Weinberg equilibrium?

    1. a) a small, isolated population
    2. b) no mutations
    3. c) random mating
    4. d) no migration in or out

  4. A J-shaped growth curve shows:

    1. a) a population crash
    2. b) a stable population
    3. c) exponential growth
    4. d) logistic growth

  5. The largest population an environment can support over time is its:

    1. a) population density
    2. b) growth rate
    3. c) carrying capacity
    4. d) biotic potential

  6. Which is a density-dependent limiting factor?

    1. a) a flood
    2. b) a forest fire
    3. c) a late spring frost
    4. d) the spread of a disease

  7. A deer population has 60 births, 20 deaths, 10 immigrants and 30 emigrants in a year. What is the change in population size?

    1. a) −20
    2. b) +40
    3. c) +20
    4. d) +60

  8. A few birds blown to an island start a new population whose allele frequencies differ from the mainland's. This is called:

    1. a) the founder effect
    2. b) natural selection
    3. c) a bottleneck
    4. d) gene flow

  9. In a population, the frequency of the recessive allele q is 0.3. What is p?

    1. a) 0.09
    2. b) 0.7
    3. c) 0.3
    4. d) 0.49

  10. In the Hardy–Weinberg equations, what does p + q equal?

    1. a) 1
    2. b) 2
    3. c) 0
    4. d) p²

Answer key · Populations · Set A

Biology 30 · maddyhelps.com

  1. c) parasitism — The tapeworm benefits and the human is harmed, which makes it parasitism (+/−).
  2. c) 0.4 — The recessive trait only shows in homozygous individuals, so q² = 0.16. Take the square root: q = 0.4. Using 0.16 as q is the classic trap.
  3. a) a small, isolated population — Equilibrium needs a large population. In a small one, chance events — genetic drift — shift allele frequencies. The other three are conditions for equilibrium.
  4. c) exponential growth — A J-curve keeps getting steeper because growth is unlimited. An S-curve (logistic) levels off at carrying capacity.
  5. c) carrying capacity — Carrying capacity (K) is where resources run out and growth levels off. Biotic potential is how fast a population could grow with no limits at all.
  6. d) the spread of a disease — Disease spreads faster when individuals are crowded together, so its effect depends on density. Fires, frost and floods hit a population the same way whatever its size.
  7. c) +20 — ΔN = (births + immigration) − (deaths + emigration) = (60 + 10) − (20 + 30) = 70 − 50 = +20.
  8. a) the founder effect — A small group founding a new population carries only a sample of the original alleles. A bottleneck is similar, but happens when an existing population is suddenly cut down.
  9. b) 0.7 — p + q = 1, so p = 1 − 0.3 = 0.7. 0.09 is q², the frequency of the recessive genotype.
  10. a) 1 — p and q are the frequencies of the only two alleles, so together they make up the whole gene pool: p + q = 1.