Question 1

Which of the following best describes the main structural components of the extracellular matrix (ECM) in animal cells and their respective functions?

Accepted Answer

Collagen fibers resist tension (pulling forces), and proteoglycans resist compression (pushing forces).

Question 2

A patient with a genetic disorder has weak cartilage that cannot withstand compression. Which ECM component is most likely defective?

Accepted Answer

Proteoglycans

Question 3

In plant cells, what is the primary function of the middle lamella, and what is it mainly composed of?

Accepted Answer

It glues adjacent cells together and is composed of pectins.

Question 4

Which type of cell junction would be most affected in a patient whose epithelial cells allow excessive leakage of water between cells?

Accepted Answer

Tight junctions

Question 5

Desmosomes are especially important in tissues that experience mechanical stress, such as skin and heart muscle. What is the main reason for this?

Accepted Answer

They connect the cytoskeletons of adjacent cells, providing strong adhesion.

Question 6

Which of the following best explains how gap junctions contribute to the coordinated contraction of heart muscle cells?

Accepted Answer

They allow ions and small molecules to pass directly between cells, enabling rapid electrical signaling.

Question 7

Plasmodesmata in plant cells are functionally similar to which structure in animal cells?

Accepted Answer

Gap junctions

Question 8

A hormone is released into the bloodstream and affects cells in distant organs. Which type of signaling is this, and what is a key feature of the hormone?

Accepted Answer

Endocrine signaling; the hormone is stable enough to travel long distances.

Question 9

Steroid hormones can pass through the plasma membrane and bind to intracellular receptors. What is the most direct result of this binding?

Accepted Answer

Direct change in gene expression in the nucleus.

Question 10

Which of the following best describes the process of signal transduction for a lipid-insoluble signaling molecule?

Accepted Answer

The signal molecule binds to a membrane receptor, which then triggers a cascade of intracellular events.

Question 11

Which of the following is a key feature of G-protein-coupled receptor (GPCR) signaling?

Accepted Answer

GPCRs activate G proteins, which then produce second messengers to amplify the signal.

Question 12

Enzyme-linked receptors, such as receptor tyrosine kinases, typically trigger which of the following intracellular events?

Accepted Answer

Phosphorylation cascades that amplify the signal.

Question 13

Which of the following best explains the concept of signal amplification in cell signaling pathways?

Accepted Answer

A single signaling molecule can trigger the activation of many intracellular molecules, leading to a large cellular response.

Question 14

Which of the following scenarios best illustrates the concept of crosstalk in cell signaling?

Accepted Answer

Two different signaling pathways interact, modifying each other's effects.

Question 15

A mutation prevents the formation of intermediate filaments in epithelial cells. Which cell junction would be most directly affected?

Accepted Answer

Desmosomes

Question 16

Which of the following best describes the difference between the symplast and apoplast in plant tissues?

Accepted Answer

The symplast is the shared cytoplasm connected by plasmodesmata, while the apoplast is the extracellular space.

Question 17

Which of the following equations best represents the amplification of a signal in a phosphorylation cascade?

Accepted Answer

$$	ext{1 Activated Kinase} ightarrow 	ext{10 Activated Kinases}$$

Question 18

Which of the following is NOT a function of the extracellular matrix (ECM) in animal cells?

Accepted Answer

Facilitating cell–cell communication via gap junctions

Question 19

A researcher observes that a certain signaling molecule binds to a receptor on the cell surface, but does not enter the cell. Which of the following is most likely true about this signaling molecule?

Accepted Answer

It is lipid-insoluble and requires a membrane receptor for signal transduction.

Cell–Cell Interactions: Structure, Adhesion, and Communication

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