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Populations and Community Dynamics — HS Environmental Science practice questions

14 multiple-choice questions and 16 flashcards on Populations and Community Dynamics, about 9% of the HS Environmental Science bank. Every one carries a written rationale.

Written and maintained by the CoStudy team · last updated 2026-10-02 · how we write and review questions

What this chapter covers

Populations and Community Dynamics is one of 11 chapters in CoStudy's HS Environmental Science bank, and it holds 14 of the bank's 150 multiple-choice questions — roughly 9% of the total. That proportion is not arbitrary: chapters follow the certifying body's published exam outline, and the number of questions in each is set by that domain's published weight, so the share of your practice time this chapter takes matches the share of the real exam it accounts for.

Studying by chapter is worth doing once you have a diagnostic score. A single overall percentage tells you whether you are close; it does not tell you which domain is dragging. Working a weak chapter in isolation, and re-testing it in isolation, is the fastest way to move a score that has stalled — and it is why the mock exams in CoStudy report by domain rather than as one number.

Free Populations and Community Dynamics practice questions

6 questions drawn from this chapter, with the full rationale shown — the controlling principle behind the right answer, and why each wrong option tempts and fails.

A logistic (S-shaped) growth curve levels off because:

  1. birth rates rise as resources shrink
  2. the population nears carrying capacity
  3. the population has no limiting factors
  4. all individuals stop reproducing

Answer: B — the population nears carrying capacity

B) Correct — Limiting factors slow growth as resources become scarce. A) Birth rates usually fall. C) Would cause exponential growth. D) Births continue but match deaths.

In predator–prey cycles, such as lynx and hares, the predator population usually:

  1. peaks before the prey population
  2. stays about the same while the prey population changes
  3. peaks shortly after the prey population peaks
  4. always outnumbers the prey

Answer: C — peaks shortly after the prey population peaks

C) Correct — More prey feeds more predators, with a lag. A) Predators need prey first. B) Predator numbers follow prey numbers. D) Prey usually outnumber predators.

Carrying capacity is:

  1. the number of offspring each female produces
  2. the largest population an area can sustain
  3. the fastest a population can grow
  4. the number of species in an area

Answer: B — the largest population an area can sustain

B) Correct — Food, water, and space set the limit. A) Is fecundity or birth rate. C) Is the maximum growth rate. D) Is species richness.

Two species that need exactly the same limited resources cannot coexist forever. This is the:

  1. 10% rule
  2. competitive exclusion principle
  3. law of the minimum
  4. tragedy of the commons

Answer: B — competitive exclusion principle

B) Correct — One species will outcompete the other or they will divide the niche. A) Describes energy transfer. C) Says growth is limited by the scarcest resource. D) Is about shared resources and human behavior.

A population grows 2% per year. Using the rule of 70, about how long until it doubles?

  1. 35 years
  2. 140 years
  3. 50 years
  4. 20 years

Answer: A — 35 years

A) Correct — Doubling time ≈ 70 ÷ growth rate (%) = 70 ÷ 2. B) Multiplies 70 × 2. C) Divides 100 by 2. D) Divides 70 by 3.5, not 2.

After a forest fire, the community regrows on existing soil. This is:

  1. primary succession
  2. eutrophication
  3. secondary succession
  4. a climax community

Answer: C — secondary succession

C) Correct — It is faster than primary succession because soil remains. A) Starts on bare rock without soil. B) Is nutrient overload in water. D) Is the late, stable stage.

Populations and Community Dynamics flashcards

1 cards from the 16 in this chapter.

Carrying capacity?

Max population size environment can sustain long-term.

Practise the full chapter

These are a sample. The full Populations and Community Dynamics chapter runs 30 items with per-chapter progress tracking, on the web and in the iOS app.

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