AP Environmental Science — Unit 3: Populations
Practice questions, answers, and key terms for Unit 3, aligned to the College Board CED.
Exam weighting: Unit 3 is 10-15% of the AP Environmental Science exam.
What AP Environmental Science Unit 3 covers
The College Board Course and Exam Description breaks Unit 3 into 9 topics:
- 3.1 Generalist and Specialist Species
- 3.2 K-Selected and r-Selected Species
- 3.3 Survivorship Curves
- 3.4 Carrying Capacity
- 3.5 Population Growth and Resource Availability
- 3.6 Age Structure Diagrams
- 3.7 Total Fertility Rate
- 3.8 Human Population Dynamics
- 3.9 Demographic Transition
AP Environmental Science Unit 3 practice questions
What is a specialist species?
A species with a narrow niche adapted to specific conditions. It thrives in stable habitats but is vulnerable to change.
A forest is fragmented by a new highway, rapidly changing habitat structure. Which type of species is more likely to survive — generalist or specialist?
Generalist species, because they exploit varied resources and tolerate change. Specialists, tied to specific resources, fare worse.
Which set of traits best describes a K-selected species?
Large body size, few offspring, high parental care, and long lifespan. Also late maturity and strong competition in stable environments.
Compare r-selected and K-selected species in terms of offspring number and parental investment.
r-selected: many offspring, minimal parental investment per offspring. K-selected: few offspring, significant energy invested per offspring.
Why are K-selected species typically more threatened by invasive species than r-selected species?
They reproduce slowly and have low biotic potential, so they can't recover quickly. Declines caused by invasive competitors or predators aren't replaced fast.
What is biotic potential?
The maximum reproductive rate of a population under ideal, unlimited conditions. Actual growth falls short because resources are limited.
What does a Type I survivorship curve indicate about a population?
Most individuals survive to old age, with mortality concentrated late in life. It's typical of K-selected species with high parental care.
Match survivorship curve types to reproductive strategies: which curves correspond to K-selected vs. r-selected species?
K-selected species follow Type I or II curves; r-selected follow Type III. Curve shape maps directly onto reproductive strategy.
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Key terms in Unit 3
These 12 terms show up in the Unit 3 cards. Each one links to its definition in the AP Environmental Science key-term reference.
Drill all of Unit 3 with spaced repetition
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