4.9 MC Answers and Review

6 min readdecember 10, 2021

AP Biology 🧬

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Answers and Review for Multiple Choice Practice on Cell Communication and Cell Cycle

STOP ⛔ Before you look at the answers, make sure you gave this practice quiz a try so you can assess your understanding of the concepts covered in Unit 4. Click here for the practice questions: AP Bio Unit 4 Multiple Choice Questions.

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Facts about the test: The AP Biology exam has 60 multiple choice questions and you will be given 1 hour 30 minutes to complete the section. That means it should take you around 15 minutes to complete 10 questions. The following questions were not written by College Board and although they cover information outlined in the AP Biology Course and Exam Description the formatting on the exam may be different.

1. Another name for a cell signal or stimulus molecule:
A. phosphorylation cascade
B. receptor protein
C. ligand
D. kinase
Answer: Although phosphorylation cascades, receptor proteins, and kinases play a role in cell signaling, they are not the ligand. In cell signaling, a ligand is the chemical messenger capable of binding to a receptor protein at the start of a cell signal. 
📄 Study AP Biology, Unit 4.2: Introduction to Signal Transduction

2. The cell cycle contains these three distinct phases:
A. interphase, mitosis, and cytokinesis
B. G1, S, G2
C. interphase, M-phase, G0
D. G0, G1, G2
Answer: G1, S and G2 are the three parts of interphase. Interphase, mitosis and cytokinesis are three separate parts to the cycle.
📄 Study AP Biology, Unit 4.6: Cell Cycle

3. A sample of cells sits under a microscope. If the majority of cells show DNA in the chromatin form, what stage of the cell cycle must they be in?
A. Mitosis
B. Prophase
C. G2
D. Interphase
Answer: A cell's DNA does not condense into chromosomes until the beginning of prophase-the first phase in mitosis.
📄 Study AP Biology, Unit 4.6: Cell Cycle

4. During this part of cell signaling, a message is relayed through a series of chemical changes that lead to the particular response.
A. Reception
B. Signal transduction
C. Response
D. Receptor-mediated response
Answer: Reception and response are the first and final component of a signaling pathway. Signal transduction refers to the internal cellular changes that occur to amplify and relay the signal so that the appropriate response occurs.
📄 Study AP Biology, Unit 4.4: Changes in Signal Transduction Pathways

5. In regards to the cell cycle, cells grow during:
A. G0, G1, G2
B. G1, S, and G2
C. G1 and G2 only
D. Interphase and Cytokinesis
Answer: Although G1 and G2 are commonly described as "growth phases" of the cell cycle,. The cell continues to grow during S phase as well.
📄 Study AP Biology, Unit 4.6: Cell Cycle

6. Mitosis : cytokinesis
A. division of the cytoplasm: division of the nuclei
B. animal cells: plant cells
C. division of the nuclei: division of the cytoplasm
D. haploid cell: diploid
Answer: During mitosis, the DNA is divided, during cytokinesis, the cytoplasm if split to create two identical daughter cells.
📄 Study AP Biology, Unit 4.6: Cell Cycle

7. The correct order of mitotic phases:
A. prophase, anaphase, metaphase, telophase
B. anaphase, metaphase, telophase, prophase
C. telophase, anaphase, metaphase, anaphase
D. prophase, metaphase, anaphase, telophase
Answer: This question should be quite easy! It's nice to have some confidence builders right?
📄 Study AP Biology, Unit 4.6: Cell Cycle

8. During anaphase:
A. sister chromatids separate and move to opposite poles
B. homologous chromosomes separate and move to opposite poles
C. chromosomes align vertically and exchange genetic material
D. sister chromatids align at the anaphase plate
Answer: Some of the answer options here are meant to confuse you as they have nothing to do with mitosis, but something to do with meiosis. Read answer options carefully!
📄 Study AP Biology, Unit 4.6: Cell Cycle

9. What type of changes can occur during signal transduction?
A. activation or deactivation of enzymes
B. phosphorylation by kinases
C. secondary messengers amplify the signal
D. all of the these
Answer: During signal transduction a variety of chemical changes can occur. The complexity of each pathway can include several different types of chemical changes such as activation/inactivation, phosphorylation, and use of secondary messengers like cAMP.
📄 Study AP Biology, Unit 4.4: Changes in Signal Transduction Pathways

10. How would a mutation that alters the shape of a receptor protein alter the cell signaling pathway?
A. If at least 1 receptor has not mutated, the response should stay the same
B. The ligand would enter through the plasma membrane and interact directly with the DNA
C. The ligand would most likely not bind to the receptor protein, and transduction of the signal would not happen
D. The ligand could bind to a different receptor protein and begin transduction that way
Answer: Without successful reception of the ligand, the signal cannot be relayed throughout the cell to cause a response.
📄 Study AP Biology, Unit 4.2: Introduction to Signal Transduction

11. Secondary messengers are small molecules used within signal transduction to help amplify the signal and coordinate the signaling pathway within the cytoplasm. These are two examples of secondary messengers used in many cell types:
A. ATP and kinases
B. Ca2+ and cAMP
C. cAMP and iP2
D. ADP and ATP
Answer: Ca2+, cAMP, and IP3 are common secondary messengers that help relay and amplify the signal. For example, they can activate kinases which then phosphorylate other molecules to continue conformational changes, leading to the appropriate cellular response.
📄 Study AP Biology, Unit 4.4: Changes in Signal Transduction Pathways

12. The parathyroid gland releases PTH (parathyroid hormone) into the bloodstream ins response to low blood calcium levels. PTH signals the bones to release stored calcium into the bloodstream. What type of feedback controls the regulation and secretion of PTH?
A. negative feedback loop
B. positive feedback loop
C. signal transduction loop
D. cell cycle loop
Answer: During mitosis, the DNA is divided, during cytokinesis, the cytoplasm is split to create to identical daughter cells.
📄 Study AP Biology, Unit 4.5: Homeostasis & Feedback Loops

13. In response to low blood calcium, PTH (parathyroid hormone) also interacts with cells of the intestines and the kidneys. Which conclusion about PTH and cell signaling can be made?
A. PTH secretion decreases in response to calcium levels
B. PTH secretion increases in response to calcium levels
C. Signals can only interact with one cell type
D. Signals can interact with multiple cell types
Answer: Since PTH can interact with cells of three different organs, it can be concluded that this one hormone is able to interact with a variety of target cells.
📄 Study AP Biology, Unit 4.3: Signal Transduction

14. If a drug inhibited binding of the microtubules to the kinetochore, the cell would:
A. stop at telophase
B. stop at prophase
C. stop at anaphase
D. stop at telophase
Answer: Microtubules attach to the kinetochore of the sister chromatids to coordinate their movement during mitosis. If the microtubules cannot attach, the cell would remain in prophase. During prophase, the microtubules have not yet attached to the kinetochore.
📄 Study AP Biology, Unit 4.7: Regulation of Cell Cycle

15. The cell cycle is highly regulated by checkpoints coordinated by levels of cyclins and their interaction with CDK's. During which checkpoint does the cell get the "green light" to begin Mitosis?
A. C checkpoint
B. M checkpoint
C. G1 checkpoint
D. G2 checkpoint
Answer: G2 is the final phase of interphase, just before mitosis. If DNA contains errors or chromosomes have not fully replicated, the cell will not receive the green light to divide. The G2 checkpoint ensures that the cell is prepared for mitosis without DNA mistakes.
📄 Study AP Biology, Unit 4.7: Regulation of Cell Cycle
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