Question 1

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

Accepted Answer

Paracrine signaling involves local mediators affecting nearby cells, 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 activation of adenylyl cyclase and subsequent production of cAMP as a second messenger.

Question 3

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

Accepted Answer

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

Question 4

Which of the following correctly describes the role of a phosphatase in cell signaling?

Accepted Answer

A phosphatase removes phosphate groups from proteins, often deactivating them.

Question 5

During the process of apoptosis in C. elegans, which of the following events occurs?

Accepted Answer

The cell is systematically dismantled and its components are packaged into vesicles for removal.

Question 6

A human somatic cell has a diploid number of $$2n = 46. $$After DNA replication during the S phase, how many chromatids and chromosomes are present in the cell?

Accepted Answer

46 chromosomes and 92 chromatids

Question 7

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

Accepted Answer

Actin filaments (microfilaments)

Question 8

A cell is observed to have a visible cell plate forming at its center during cytokinesis. What type of cell is this, and what is the significance of the cell plate?

Accepted Answer

Plant cell; the cell plate will develop into a new cell wall separating the two daughter cells.

Question 9

Which checkpoint in the cell cycle is primarily responsible for ensuring that all chromosomes are properly attached to the spindle before allowing the cell to proceed to anaphase?

Accepted Answer

M checkpoint

Question 10

Which of the following statements about homologous chromosomes is correct?

Accepted Answer

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

Question 11

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 random alignment of homologous chromosome pairs at the metaphase plate

Question 12

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

Accepted Answer

Pairing of homologous chromosomes and crossing over

Question 13

A plant with genotype YyRr (heterozygous for both seed color and shape) is self-crossed. According to Mendel's laws, what is the expected phenotypic ratio in the F2 generation for seed color and shape?

Accepted Answer

9:3:3:1

Question 14

In a testcross between an individual with genotype Aa and an individual with genotype aa, what is the expected phenotypic ratio among the offspring?

Accepted Answer

1:1

Question 15

A true-breeding purple-flowered pea plant (PP) is crossed with a true-breeding white-flowered pea plant (pp). What will be the genotype and phenotype of the F1 generation?

Accepted Answer

All Pp; all purple flowers

Question 16

If two heterozygous individuals (Aa) are crossed, what is the probability that their offspring will be homozygous recessive (aa)? Use the multiplication rule.

Accepted Answer

$$0.25$$

Question 17

Which of the following best describes the difference between genotype and phenotype?

Accepted Answer

Genotype refers to the genetic makeup of an organism, while phenotype refers to its observable traits.

Question 18

A cell is exposed to a signal that causes Ca$$^{2+}$$ ions to be released from the endoplasmic reticulum (ER) into the cytosol. Which second messenger is directly involved in this process, and how is it produced?

Accepted Answer

IP$$_3$$, produced from PIP$$_2 by $$phospholipase C

Question 19

A patient is diagnosed with cancer due to a mutation that disables the G1 checkpoint in the cell cycle. Which of the following best explains how this mutation contributes to cancer development?

Accepted Answer

Cells proceed through the cell cycle without proper regulation, allowing damaged DNA to be passed on.

Question 20

A woman with genotype AaBb (heterozygous for two genes) has children with a man who is aabb. What is the probability that their child will be AaBb? (Assume independent assortment.)

Accepted Answer

$$0.25$$

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

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