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AP Biology Unit 8 — Ecology

One-page sprint review

Ten pages on animal behavior, energy flow, population growth, community ecology, biodiversity, and ecosystem disruption — the capstone unit that ties together every prior unit.

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Exam Weight
10–15%
MCQs
6–9
FRQ Appearance
Very Frequent
Sprint Time
~2 hours

Quick Glance — all topics in this unit

Priority, exam format, and the trap that most often costs the point. Transcribed from page 1 so this content is searchable.

TopicPriorityFormatKey trap / must-know
8.1 Behavioral Responses★★MCQTaxis = directed movement; kinesis = undirected speed change. Photoperiodism ≠ phototropism.
8.2 Energy Flow & Cycles★★★MCQ, Calc, FRQFood web arrows point FROM prey TO predator. ~10% rule: only ~10% transferred per level.
8.3–8.4 Population Ecology★★★MCQ, Calc, DataLogistic growth: max rate at N = K/2, NOT K. Density-dependent vs density-independent.
8.5 Community Ecology★★★MCQ, FRQMutualism (+/+) ≠ commensalism (+/0). Competitive exclusion → niche partitioning.
8.6 Biodiversity★★★MCQ, FRQKeystone species: disproportionate impact relative to abundance. Removal → community collapse.
8.7 Disruptions★★★MCQ, FRQBiomagnification increases up trophic levels. Eutrophication: N + P → algae → O2 crash.

Topic-by-topic visual review

Nine pages, one topic each. Open the PDF for print quality, or scroll to study on screen.

Cover: Unit 8 overview — the capstone unit. Ties Unit 1–7 concepts into ecosystem-scale questions.
Cover  ·  Unit 8 overview — the capstone unit. Ties Unit 1–7 concepts into ecosystem-scale questions.
8.1 Animal Behavior: Innate vs learned behaviors, fixed action patterns, taxis vs kinesis movement.
8.1 Animal Behavior  ·  Innate vs learned behaviors, fixed action patterns, taxis vs kinesis movement.
8.2 Energy Flow & Trophic Pyramids: 10% energy transfer rule, food chains vs food webs, biomass vs energy pyramids.
8.2 Energy Flow & Trophic Pyramids  ·  10% energy transfer rule, food chains vs food webs, biomass vs energy pyramids.
8.2 Biogeochemical Cycles: Carbon, nitrogen, phosphorus, water cycles and human impacts on each.
8.2 Biogeochemical Cycles  ·  Carbon, nitrogen, phosphorus, water cycles and human impacts on each.
8.3 Population Growth: Exponential vs logistic growth curves, carrying capacity, K-selected vs r-selected species.
8.3 Population Growth  ·  Exponential vs logistic growth curves, carrying capacity, K-selected vs r-selected species.
8.5 Community Interactions: Predation, competition, symbiosis (mutualism, commensalism, parasitism) with examples.
8.5 Community Interactions  ·  Predation, competition, symbiosis (mutualism, commensalism, parasitism) with examples.
8.5 Niche & Competitive Exclusion: Realized vs fundamental niche, competitive exclusion principle, niche partitioning.
8.5 Niche & Competitive Exclusion  ·  Realized vs fundamental niche, competitive exclusion principle, niche partitioning.
8.6 Biodiversity & Keystone Species: Species richness vs evenness, keystone species impact, ecosystem services.
8.6 Biodiversity & Keystone Species  ·  Species richness vs evenness, keystone species impact, ecosystem services.
8.7 Disruptions & Climate Change: Invasive species, habitat fragmentation, biomagnification, eutrophication, climate change effects.
8.7 Disruptions & Climate Change  ·  Invasive species, habitat fragmentation, biomagnification, eutrophication, climate change effects.
Final Review — Traps + Checklist: Top Unit 8 ecology traps and the pre-exam checklist for the capstone unit.
Final Review — Traps + Checklist  ·  Top Unit 8 ecology traps and the pre-exam checklist for the capstone unit.

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