Question 1

Which of the following best describes the analogy between reinforced concrete and the extracellular matrix (ECM) in animal tissues?

Accepted Answer

Concrete (ground substance) resists compression, while steel rods (fibers) resist tension, similar to how proteoglycans and collagen function in the ECM.

Question 2

Which component of the plant cell wall is primarily responsible for resisting tensile (pulling) forces?

Accepted Answer

Cellulose microfibrils

Question 3

What is the main function of the middle lamella in plant tissues?

Accepted Answer

It glues adjacent plant cells together by being rich in pectins.

Question 4

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

Accepted Answer

Gap junctions

Question 5

Which of the following best describes the fibrous and ground substance components of the animal extracellular matrix (ECM)?

Accepted Answer

Fibrous component is collagen; ground substance is proteoglycans.

Question 6

Which type of cell junction in animal tissues is primarily responsible for preventing the passage of substances between adjacent cells?

Accepted Answer

Tight junctions

Question 7

A signaling molecule that is lipid-soluble will most likely bind to its receptor in which location?

Accepted Answer

In the cytoplasm of the target cell

Question 8

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

Accepted Answer

Activation of a G protein by exchange of GDP for GTP

Question 9

Second messengers in signal transduction pathways are characterized by which property?

Accepted Answer

They are small molecules that diffuse rapidly and can have multiple roles in different cells.

Question 10

Which of the following best describes the sequence of events in receptor tyrosine kinase (RTK) signaling?

Accepted Answer

Ligand binding, receptor dimerization, autophosphorylation, activation of Ras, phosphorylation cascade

Question 11

Which of the following is a possible ultimate response to a cell–cell signal?

Accepted Answer

A change in the expression of specific genes

Question 12

Why is signal deactivation important in cell signaling pathways?

Accepted Answer

It allows the cell to remain sensitive to small changes in signaling.

Question 13

A mutation prevents the removal of phosphate groups from proteins in a phosphorylation cascade. What is the most likely consequence?

Accepted Answer

The signal will remain active longer than normal.

Question 14

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

Accepted Answer

Only cells with the appropriate signal receptor will respond.

Question 15

Which of the following is true about the role of integrins in animal cells?

Accepted Answer

They connect the cytoskeleton to the extracellular matrix.

Question 16

A researcher adds a hydrophilic signaling molecule to a culture of animal cells. Where would you expect to find the receptors for this molecule?

Accepted Answer

On the cell's plasma membrane

Question 17

Which of the following best describes the function of desmosomes?

Accepted Answer

They connect the cytoskeletons of adjacent cells, providing mechanical strength.

Question 18

Which of the following is a direct result of G protein activation in a signal transduction pathway?

Accepted Answer

Production of a second messenger

Question 19

Which of the following statements about second messengers is FALSE?

Accepted Answer

They are always proteins.

Question 20

A patient has a genetic defect that prevents the formation of gap junctions in heart muscle cells. Which of the following symptoms would you most likely expect?

Accepted Answer

Impaired electrical signaling between heart cells, leading to arrhythmias

Cell–Cell Interactions: Structure, Communication, and Signal Transduction

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