Unit 4: Cell Communication and Cell Cycle

AP Biology — 24 practice questions with detailed explanations. Use the links below to open each full question page (ideal for search indexing and deep study).

Unit summary

This unit covers core ideas tested on the AP exam. Each listed item links to a standalone page with the full stem, answer choices where applicable, a step-by-step explanation, and the correct answer. Difficulty labels help you prioritize review.

Questions in this unit

In a G-protein-coupled receptor (GPCR) pathway, a ligand binds to the receptor and activates a G protein, which then activates adenylyl cyclase. What is the most likely direct role of cyclic AMP (cAMP) in this pathway?hard · mcq · 1 pt
A eukaryotic cell has a haploid number of n = 12. What is the total number of sister chromatids present in a single cell at the end of the S phase?easy · mcq · 1 pt
A neurotransmitter is released from a neuron and diffuses across the synaptic cleft to bind receptors on an adjacent muscle cell. This is an example of which type of cell signaling?hard · mcq · 1 pt
When blood glucose levels increase, beta cells of the pancreas release insulin, which stimulates body cells to take up glucose. As glucose levels fall, insulin secretion decreases. This regulation is an example of:hard · mcq · 1 pt
During which phase of mitosis do the sister chromatids physically separate and begin moving toward opposite poles of the cell?hard · mcq · 1 pt
A cell in the G2 phase of the cell cycle is found to have incompletely replicated DNA. Which of the following outcomes is most likely?hard · mcq · 1 pt
A researcher introduces a mutation that causes a receptor tyrosine kinase (RTK) to dimerize and autophosphorylate even in the absence of its ligand. What is the most likely consequence for the cell?hard · mcq · 1 pt
A liver cell responds to epinephrine by breaking down glycogen. A single molecule of epinephrine can ultimately result in the breakdown of millions of glycogen molecules. Which mechanism best accounts for this observation?medium · mcq · 1 pt
During mitosis, a cell undergoes a series of coordinated events to ensure accurate chromosome segregation. Which of the following is a critical checkpoint that regulates this process?hard · mcq · 1 pt
A researcher is studying the role of feedback loops in regulating the cell cycle. Based on the data, which of the following is a characteristic of feedback loops in the cell cycle?medium · mcq · 1 pt
A cell is experiencing stress due to a lack of essential nutrients. Based on the data, which of the following is a primary mechanism by which the cell responds to this stress?easy · mcq · 1 pt
In a study on the effects of caffeine on cell signaling pathways, researchers find that caffeine inhibits the activity of protein kinase A (PKA). Based on this information, which of the following is a likely explanation for caffeine's effect?hard · mcq · 1 pt
A researcher discovers a new compound that inhibits the G1/S checkpoint in the cell cycle. Based on this information, which of the following would be a likely effect on the cell?medium · mcq · 1 pt
Based on the data, which of the following best describes the relationship between the G2 phase and the mitotic spindle formation?hard · mcq · 1 pt
Which of the following types of signaling pathway is most effective in controlling cell growth in response to environmental stimuli?medium · mcq · 1 pt
The primary reason a cell would undergo meiosis is toeasy · mcq · 1 pt
Which of the following is a characteristic of a feedforward loop in the context of cell cycle regulation?hard · mcq · 1 pt
The primary reason a cell would undergo quiescence is tomedium · mcq · 1 pt
Which of the following types of cell cycle regulation is most effective in ensuring that cells do not divide in the presence of DNA damage?hard · mcq · 1 pt
Based on the data, which of the following best describes the relationship between cyclin-dependent kinases and the cell cycle?medium · mcq · 1 pt
The primary reason a cell would undergo mitosis is toeasy · mcq · 1 pt
Which of the following types of feedback loop would be most effective in controlling cell growth in response to nutrient availability?hard · mcq · 1 pt
Based on the data, which of the following best describes the relationship between cell growth and the G1 phase of the cell cycle?medium · mcq · 1 pt
Which of the following is a primary reason a signal transduction pathway is a good example of an amplification system?easy · mcq · 1 pt

Sample prompts

Short previews of topics covered (not full question text).

In a G-protein-coupled receptor (GPCR) pathway, a ligand binds to the receptor a…
A eukaryotic cell has a haploid number of n = 12. What is the total number of si…
A neurotransmitter is released from a neuron and diffuses across the synaptic cl…
When blood glucose levels increase, beta cells of the pancreas release insulin, …
During which phase of mitosis do the sister chromatids physically separate and b…
A cell in the G2 phase of the cell cycle is found to have incompletely replicate…
A researcher introduces a mutation that causes a receptor tyrosine kinase (RTK) …
A liver cell responds to epinephrine by breaking down glycogen. A single molecul…
During mitosis, a cell undergoes a series of coordinated events to ensure accura…
A researcher is studying the role of feedback loops in regulating the cell cycle…
A cell is experiencing stress due to a lack of essential nutrients. Based on the…
In a study on the effects of caffeine on cell signaling pathways, researchers fi…