AP Biology Unit 4 Practice Test: Cell Communication and Cell Cycle
Practise AP Biology Unit 4 with tests on signal transduction, cell cycle checkpoints, mitosis, and apoptosis. AP-style MCQ and FRQ with detailed explanations.
What Unit 4 Covers in AP Biology
Unit 4 bridges molecular biology and organismal physiology by examining how cells receive, process, and respond to signals — and how cell division is regulated. AP Biology tests these concepts with diagram-based MCQs and complex FRQs that require step-by-step mechanistic explanations.
Core Topics in Unit 4
Signal Transduction Pathways
Signal transduction involves three stages: reception (ligand binds receptor), transduction (signal cascade amplifies the message), and response (cellular outcome). Key receptors include G-protein-coupled receptors, receptor tyrosine kinases, and intracellular receptors. AP FRQs frequently ask you to explain a cascade step-by-step or predict the effect of disrupting a component.
Types of Cell Communication
Cells communicate over varying distances: autocrine signalling (self), paracrine signalling (local neighbours), and endocrine signalling (distant, via bloodstream). AP questions test your ability to categorise communication types and connect them to biological examples such as hormones, neurotransmitters, and local mediators.
Feedback Loops
Negative feedback maintains homeostasis; positive feedback amplifies a response toward a completion point. Blood glucose regulation and the clotting cascade are classic AP Biology examples of each.
Mitosis Phases and the Cell Cycle
Know the stages of the cell cycle: G1, S, G2 (interphase) and the mitotic phases (prophase, metaphase, anaphase, telophase, cytokinesis). AP questions often present cell cycle diagrams and ask you to identify phases or predict outcomes of checkpoint failures.
Cell Cycle Checkpoints and Apoptosis
Checkpoints (G1, G2, spindle assembly) monitor DNA integrity and cell readiness. Proto-oncogenes, tumour suppressor genes, and apoptosis connect cell cycle regulation to cancer biology — a recurring AP FRQ context.
AP Science Practice Skills for Unit 4
- Data analysis: Interpreting cell cycle diagrams, mitotic index calculations, and signalling pathway charts
- Experimental design: Designing investigations to test the effects of signalling molecule inhibitors
- Scientific argumentation: Explaining how a mutation in a checkpoint gene leads to uncontrolled cell division
How GradePerfect Tests Unit 4
Our AP-style Unit 4 test presents signal cascade diagrams, cell cycle graphs, and FRQ prompts requiring detailed mechanistic explanations — exactly the reasoning skills AP Biology rewards.