Question 1

Which of the following best describes the difference between paracrine signaling and endocrine signaling in multicellular organisms?

Accepted Answer

Paracrine signaling acts on nearby cells by releasing local mediators, while endocrine signaling involves hormones traveling through the bloodstream to distant target cells.

Question 2

A researcher discovers a mutation in a cell that prevents the activation of G protein coupled receptors (GPCRs). Which of the following processes would most likely be directly affected?

Accepted Answer

The production of the second messenger cAMP in response to extracellular signals.

Question 3

Which of the following best explains why only certain cells in the body respond to a specific hormone?

Accepted Answer

Only cells that have the specific receptor for the hormone are able to respond to the signal.

Question 4

During the process of apoptosis in the nematode C. elegans, which of the following is a key event?

Accepted Answer

Activation of caspase proteins that lead to controlled cell death.

Question 5

If a human somatic cell is in G1 phase and has a diploid number of $$2n = 46$$, how many chromosomes and chromatids will be present in the cell after DNA replication (S phase) is complete?

Accepted Answer

46 chromosomes and 92 chromatids

Question 6

Which cytoskeletal component is primarily responsible for the formation of the cleavage furrow during cytokinesis in animal cells?

Accepted Answer

Actin filaments (microfilaments)

Question 7

A cell is observed to have a single, circular chromosome and divides by binary fission. Which of the following statements is most accurate?

Accepted Answer

This cell is likely a prokaryotic cell, and does not undergo mitosis or meiosis.

Question 8

Which of the following events is unique to meiosis I and does NOT occur during mitosis?

Accepted Answer

Pairing and crossing over of homologous chromosomes

Question 9

During which phase of meiosis does independent assortment of chromosomes occur, and how does this process contribute to genetic variation?

Accepted Answer

Metaphase I; by randomly aligning homologous chromosome pairs at the metaphase plate

Question 10

A plant with genotype YyRr (yellow, round seeds) is crossed with a plant with genotype yyrr (green, wrinkled seeds). According to Mendel's laws, what is the expected phenotypic ratio among the offspring?

Accepted Answer

1 yellow round : 1 yellow wrinkled : 1 green round : 1 green wrinkled

Question 11

In a monohybrid cross between two heterozygous pea plants (Pp x Pp), what is the expected genotypic ratio among the F2 offspring?

Accepted Answer

1 PP : 2 Pp : 1 pp

Question 12

A woman with genotype AaBb (for two independently assorting genes) has children with a man who is aabb. What is the probability that their child will have the genotype AaBb?

Accepted Answer

$$0.25$$

Question 13

Which of the following best describes the function of a phosphatase enzyme in cell signaling?

Accepted Answer

It removes phosphate groups from proteins, often deactivating them.

Question 14

A cell is unable to pass the G1 checkpoint in the cell cycle. Which of the following is the most likely consequence?

Accepted Answer

The cell will remain in G0 phase and not divide.

Question 15

Which of the following is true regarding homologous chromosomes?

Accepted Answer

They carry the same genes in the same order, but may have different alleles.

Question 16

A cell biologist observes that a plant cell is forming a cell plate during cytokinesis. What is the significance of this observation?

Accepted Answer

The cell is undergoing cytokinesis typical of plant cells, where vesicles coalesce at the center to form a new cell wall.

Question 17

Which of the following best describes the role of cAMP as a second messenger in cell signaling?

Accepted Answer

cAMP is produced from ATP by the enzyme adenylyl cyclase and activates protein kinase A.

Question 18

If a testcross between an individual with an unknown genotype and a homozygous recessive individual produces a 1:1 phenotypic ratio, what is the genotype of the unknown individual?

Accepted Answer

Heterozygous

Question 19

Which of the following best explains why cancer cells can divide uncontrollably?

Accepted Answer

They ignore cell cycle checkpoints and continue dividing even when DNA is damaged.

Question 20

A geneticist is studying a trait that follows Mendel's law of independent assortment. If two heterozygous individuals (AaBb) are crossed, what is the probability that an offspring will be homozygous recessive for both genes (aabb)?

Accepted Answer

$$\frac{1}{16}$$

Cell Communication, Cell Cycle, Meiosis, and Mendelian Genetics: Study Guide for Chapters 11-14

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