---
title: "AP Environmental Science Unit 1 Practice Test"
description: "A timed AP Environmental Science Unit 1 (The Living World: Ecosystems) practice test in the AP format, drawn from 1,142 multiple-choice questions and 38 FRQs written for the unit. The standard version takes about 70 minutes."
canonical: "https://fiveable.me/ap-enviro/unit-test/1"
type: "unit-test"
subject: "AP Environmental Science"
unit: "Unit 1"
---

# AP Environmental Science Unit 1 Practice Test

## Overview

A timed AP Environmental Science Unit 1 (The Living World: Ecosystems) practice test in the AP format, drawn from 1,142 multiple-choice questions and 38 FRQs written for the unit. The standard version takes about 70 minutes.

## Test Format

- 20 Multiple Choice Questions (23 minutes)
- 1 FRQ – FRQ 1 – Design an Investigation (23 minutes)
- 1 FRQ – FRQ 2 – Analyze and Interpret Quantitative Data (23 minutes)

## Unit FRQs by Type

- [FRQ 1 – Design an Investigation](/ap-enviro/frqs/design-an-investigation?unit=1): 11 questions
- [FRQ 2 – Analyze and Interpret Quantitative Data](/ap-enviro/frqs/data-analysis?unit=1): 9 questions
- [FRQ 3 – Analyze an Environmental Problem Doing Calculations](/ap-enviro/frqs/calculations?unit=1): 18 questions

## Practice Questions

### Question 1

In a tide pool ecosystem, sea stars and sea urchins both feed on kelp. Sea stars are predators of sea urchins, but sea urchins are more efficient kelp grazers and can consume kelp faster than sea stars can consume urchins. When sea star populations decline due to disease, urchin populations initially increase. However, kelp biomass decreases so severely that both urchin and sea star populations subsequently decline. Which of the following best explains why the sea star population declines despite the removal of disease pressure?

- (A) Urchin populations increased unchecked and overgrazed kelp, depleting the resource base that sea stars indirectly depend on through their urchin prey.
- (B) The disease that initially killed sea stars mutated to affect urchins, causing urchin populations to decline and eliminating sea star food sources.
- (C) Sea stars require kelp as a direct food source and cannot survive on urchin meat alone, so kelp depletion causes sea star starvation.
- (D) Increased urchin populations produce chemical compounds that inhibit sea star reproduction, preventing population recovery even after disease declines.

**Answer: (A)** Understanding indirect resource effects requires recognizing that sea stars depend on kelp availability not directly (they don't eat it) but indirectly through their prey. When sea stars decline, urchin populations explode and overgraze kelp. The resulting kelp depletion reduces urchin population size and condition, eliminating the resource (healthy urchin prey) that sea stars require. This demonstrates how resource availability influences species interactions across multiple trophic levels—sea stars' survival depends on maintaining urchin populations, which requires adequate kelp. The removal of predation pressure paradoxically leads to resource depletion that harms the predator.

### Question 2

In a coral reef ecosystem, a symbiotic relationship exists between corals and zooxanthellae (photosynthetic algae living in coral tissues). When water temperatures increase by 3°C above normal, corals expel their zooxanthellae in a process called bleaching. Coral survival depends on rapidly reestablishing the symbiosis with zooxanthellae. Which of the following best explains why corals cannot survive long-term without zooxanthellae despite being able to feed on plankton?

- (A) Zooxanthellae provide the majority of coral energy through photosynthetic products, and plankton feeding alone cannot supply sufficient energy to meet coral metabolic demands.
- (B) Zooxanthellae produce chemical compounds that corals require for skeleton formation, and without these compounds, corals cannot build or maintain their calcium carbonate structures.
- (C) Bleached corals lose the ability to capture plankton because zooxanthellae produce enzymes necessary for plankton digestion.
- (D) Temperature increase directly damages coral tissues, making them unable to process any food source, including plankton.

**Answer: (A)** Understanding mutualistic symbiosis requires recognizing that both partners depend on resource exchange—in this case, energy resources. Corals evolved to depend primarily on energy from zooxanthellae photosynthesis rather than plankton capture alone. While corals retain the ability to feed on plankton, this mechanism cannot provide sufficient energy to sustain coral metabolism and growth. The mutualistic relationship represents a resource dependency where zooxanthellae provide the primary energy resource. Bleaching eliminates this resource, causing coral starvation despite the theoretical availability of plankton. This demonstrates how resource availability through mutualistic partnerships fundamentally influences species survival.

### Question 3

A parasitic fungus reduces oak acorn production by 60%. Blue jays that depend on acorns decline while wood-boring beetles that feed on dead and weakened oak wood increase. Which best explains these divergent population trends?

- (A) Fungal infection increases dead wood for beetles and reduces acorn supply to jays.
- (B) Beetles benefit from increased dead wood, not from generalist diet flexibility.
- (C) Fungal infection kills wood insects and lets jays thrive on increased insect prey.
- (D) Jays and beetles use different resources and do not compete directly.

**Answer: (A)** The fungus weakens trees and lowers acorn production while creating more dead wood that beetles use. Beetles therefore gain resources and increase while acorn-dependent jays decline.

### Question 4

Two herbivore species compete for limited grass resources in a savanna. The available grass biomass is 29,200 kg. Species A requires 2.5 kg of grass per individual annually, and Species B requires 3.2 kg per individual annually. If Species A has a population of 8,400 individuals and Species B has 6,200 individuals, what is the total resource deficit (in kg) when both populations attempt to meet their annual requirements?

- (A) 11,640 kg
- (B) 5,840 kg
- (C) 40,840 kg
- (D) 3,160 kg

**Answer: (A)** Total demand is Species A's 8,400 × 2.5 = 21,000 kg plus Species B's 6,200 × 3.2 = 19,840 kg, which is 40,840 kg. Subtracting the 29,200 kg of available grass gives a deficit of 11,640 kg, showing how combined demand beyond limited supply drives competition.

### Question 5

In a savanna ecosystem, lions and hyenas both hunt zebras and wildebeest. When prey populations decline due to drought, competition between these predators intensifies. Which of the following best explains why reduced prey availability increases competitive pressure between these predator species?

- (A) Scarce prey forces both predator species to hunt the same prey items more intensively, increasing direct competition for limited food resources.
- (B) Scarce prey forces both predator species to expand their territorial ranges, increasing direct competition for limited hunting territories.
- (C) Scarce prey forces both predator species to hunt the same prey items more intensively, increasing territorial defense behaviors rather than competition for food.
- (D) Scarce prey forces hyenas to hunt the same prey items as lions more intensively, increasing direct competition because hyenas are subordinate competitors.

**Answer: (A)** Understanding how resource scarcity intensifies competition requires recognizing that when resources become limiting, organisms cannot avoid competing for the same items. The correct answer demonstrates that reduced prey availability eliminates the possibility of resource partitioning, forcing both predators to compete directly for the same limited food supply, directly addressing EK ERT-1.A.3.

### Question 6

In a rocky intertidal zone, mussels and sea stars occupy the same rocks. Mussels are abundant when sea stars are few. When sea stars increase and consume many mussels, mussel numbers decline sharply. Which best describes this interaction?

- (A) Predator-prey relationship, with sea stars actively preying on mussels.
- (B) Interspecific competition where both species directly compete for the same rock space.
- (C) Mutualism in which both species gain benefits from the interaction.
- (D) Commensalism where one benefits while the other remains unaffected.

**Answer: (A)** Sea stars consume mussels, creating a predator-prey dynamic. Mussel abundance directly affects sea star populations through food availability.

### Question 7

Ecologists studied how prey availability influenced predator populations by measuring rabbit and lynx densities monthly for ten years in the same boreal forest region. Which of the following best describes the research method used in this study?

- (A) Longitudinal field study using repeated population sampling to track predator-prey dynamics over time
- (B) Single-year observational survey comparing rabbit and lynx populations at one point in time
- (C) Controlled laboratory experiment manipulating prey availability while measuring predator feeding behavior
- (D) Comparative study measuring lynx populations in regions with high rabbit density versus regions with low rabbit density at a single time point

**Answer: (A)** Identifying the research method requires recognizing that monthly measurements across ten years constitute longitudinal monitoring of natural populations. This temporal replication is essential for observing how resource availability (prey density) influences predator population responses, demonstrating understanding of LO 1.1.A (resource availability influences species interactions). The extended timeframe captures predator-prey cycles that would be invisible in short-term studies.

### Question 8

A researcher studied resource partitioning in two lizard species by recording foraging behavior, prey size and type, and microhabitat across 12 desert locations over six months. Why does sampling multiple locations strengthen the study?

- (A) Spatial replication shows partitioning is consistent across environmental variation
- (B) Increasing sample size improves population estimates but not spatial replication
- (C) Sampling different locations reveals variation in prey availability
- (D) Multiple locations do not reduce observer bias when a single researcher collects data

**Answer: (A)** Replication across locations demonstrates the pattern holds despite environmental heterogeneity. Sampling 12 sites strengthens the inference that resource partitioning reliably reduces competition rather than reflecting a local anomaly.

### Question 9

Ecologists studying how prey availability influences predator population dynamics in a grassland ecosystem established 12 study plots and counted prairie dog populations monthly while tracking coyote sightings using camera traps for 36 months. They also measured vegetation biomass quarterly to assess food availability for prairie dogs. Which of the following best describes this research method?

- (A) An observational study examining correlations between changes in prey availability and predator population responses over time
- (B) A manipulative experiment examining correlations between changes in prey availability and predator population responses across 12 plots over 36 months
- (C) An observational study establishing that changes in prey availability cause predator population responses over time
- (D) An observational study examining correlations between prey availability and predator populations at a single point in time across 12 plots

**Answer: (A)** Identifying the research method requires recognizing that ecologists measured existing populations without manipulating them. The repeated measurements across multiple variables (prairie dog density, coyote presence, vegetation biomass) over 36 months characterize an observational study designed to detect correlational patterns between resource availability and predator dynamics, directly testing how resource limitation influences species interactions.

### Question 10

Ecologists investigating how predator presence influences prey population size established 24 experimental plots in a grassland. Twelve plots were enclosed with predator-proof fencing while twelve plots remained open to predators. All plots were matched for initial vegetation and soil conditions. They counted herbivore populations monthly for 18 months and measured vegetation biomass quarterly. Which of the following best describes the experimental design?

- (A) A manipulative experiment using fenced and unfenced plots as replicates to test how predator exclusion affects herbivore population growth
- (B) An observational study comparing herbivore populations in naturally predator-free areas to areas with predators present
- (C) A manipulative experiment using fenced and unfenced plots to determine which herbivore species is the superior competitor for vegetation
- (D) A manipulative experiment testing predator exclusion effects using only fenced plots without unfenced control plots

**Answer: (A)** Identifying the experimental design requires recognizing the manipulation of predator access and the replicated treatment (fenced) and control (unfenced) plots. This design directly tests how predator presence influences prey population dynamics by comparing herbivore growth when predation is eliminated versus when it occurs naturally, demonstrating the causal relationship between predator-prey interactions and resource availability effects on population size.

## Review the Unit

- [1.1 Introduction to Ecosystems](/ap-enviro/unit-1/intro-ecosystems/study-guide/IR1y6F8EcTH2cQsPbCHQ)
- [1.2 Terrestrial Biomes](/ap-enviro/unit-1/terrestrial-biomes/study-guide/itE0pooQYg0jGiYtQnws)
- [1.3 Aquatic Biomes](/ap-enviro/unit-1/aquatic-biomes/study-guide/Ka0nsiIoWMSAbSKgVUqC)
- [1.4 The Carbon Cycle](/ap-enviro/unit-1/carbon-cycle/study-guide/DgNVtqUbzmk6j54jVo7q)
- [1.5 The Nitrogen Cycle](/ap-enviro/unit-1/nitrogen-cycle/study-guide/2pAcyAUnoJkC6dEVNgxE)
- [1.6 The Phosphorous Cycle](/ap-enviro/unit-1/phosphorus-cycle/study-guide/JujZhatUDATN9fbpaIv9)
- [1.7 The Hydrologic Cycle](/ap-enviro/unit-1/hydrologic-cycle/study-guide/Mnp6Jfh7MANP2YtOhxCb)
- [1.8 Primary Productivity](/ap-enviro/unit-1/primary-productivity/study-guide/qZAeWALqqSWPTQRTlPLB)
- [1.9 Trophic Levels](/ap-enviro/unit-1/trophic-levels/study-guide/zuTydZBp5i87EOaR0jGz)
- [1.10 Energy Flow and the 10% Rule](/ap-enviro/unit-1/energy-flow-10-percent-rule/study-guide/TRmVEr5JN1FSSPwzXICg)
- [1.11 Food Chains and Food Webs](/ap-enviro/unit-1/food-chains-food-webs/study-guide/4fCgW98LwgSPkma8myW5)

## Other Unit Tests

- [Unit 2: The Living World: Biodiversity](/ap-enviro/unit-test/2)
- [Unit 3: Populations](/ap-enviro/unit-test/3)
- [Unit 4: Earth Systems & Resources](/ap-enviro/unit-test/4)
- [Unit 5: Land & Water Use](/ap-enviro/unit-test/5)
- [Unit 6: Energy Resources & Consumption](/ap-enviro/unit-test/6)
- [Unit 7: Atmospheric Pollution](/ap-enviro/unit-test/7)
- [Unit 8: Aquatic & Terrestrial Pollution](/ap-enviro/unit-test/8)
- [Unit 9: Global Change](/ap-enviro/unit-test/9)

## About This Document

Canonical Fiveable pages are available as Markdown at the same path plus `.md`.

- [llms.txt](https://fiveable.me/llms.txt): index of Fiveable's sections and URL patterns
- [llms-full.txt](https://fiveable.me/llms-full.txt): complete subject and unit listing
- [MCP server](https://fiveable.me/mcp): call Fiveable as tools instead of fetching pages (`https://fiveable.me/api/mcp`)
- [MCP server for AP teachers](https://fiveable.me/mcp/teachers): a teacher's classes, assignments and AP-rubric grading (`https://fiveable.me/api/mcp/teacher`)