Question 1

Which of the following best describes the main function of the extracellular matrix (ECM) in animal cells?

Accepted Answer

It acts as a fiber composite that provides structural support and helps cells attach to one another.

Question 2

A researcher is studying a bacterial species with a thick peptidoglycan layer and no outer membrane. Which type of cell wall does this bacterium have?

Accepted Answer

Gram-positive cell wall

Question 3

Which of the following is a key difference between the cell walls of bacteria and archaea?

Accepted Answer

Bacterial cell walls contain peptidoglycan, while archaeal cell walls do not.

Question 4

In plants, what is the main function of pectin found in the primary cell wall?

Accepted Answer

To keep the cell wall moist and flexible

Question 5

Which of the following best explains why tight junctions are important in epithelial tissues?

Accepted Answer

They form a watertight seal that prevents leakage of materials between cells.

Question 6

A mutation disrupts the function of integrins in an animal cell. Which process would be most directly affected?

Accepted Answer

Attachment of the cytoskeleton to the extracellular matrix

Question 7

Which of the following is a correct sequence of events in G-protein-coupled receptor (GPCR) signal transduction?

Accepted Answer

Signal binds receptor → G protein exchanges GDP for GTP → G protein activates enzyme → Second messenger produced

Question 8

Which of the following best describes the role of second messengers in cell signaling?

Accepted Answer

They amplify the signal received by the receptor and can activate protein kinases.

Question 9

A plant cell is exposed to drought conditions and secretes abscisic acid. What is the most likely cellular response?

Accepted Answer

Guard cells respond by closing pores to reduce water loss.

Question 10

Which of the following statements about desmosomes is correct?

Accepted Answer

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

Question 11

Which of the following best explains the concept of 'crosstalk' in cell signaling?

Accepted Answer

It describes the integration and interaction of multiple signaling pathways within a cell.

Question 12

Which of the following is a real-world example of quorum sensing in bacteria?

Accepted Answer

Bacteria forming a biofilm on teeth as population density increases

Question 13

Which of the following best describes the difference between plasmodesmata in plant cells and gap junctions in animal cells?

Accepted Answer

Plasmodesmata connect the cytoplasm and smooth ER of adjacent plant cells, while gap junctions form protein channels between animal cells.

Question 14

A hormone is classified as lipid-soluble. Which of the following is most likely true about its signaling pathway?

Accepted Answer

It diffuses through the plasma membrane and binds to a receptor in the cytoplasm.

Question 15

Which of the following equations correctly represents the activation of a G protein by GTP?

Accepted Answer

$$	ext{G protein} + 	ext{GTP} ightarrow 	ext{Active G protein-GTP complex}$$

Question 16

Which of the following best describes the function of receptor tyrosine kinases (RTKs) in cell signaling?

Accepted Answer

They are enzyme-linked receptors that trigger a phosphorylation cascade inside the cell.

Question 17

Which of the following is a correct description of the middle lamella in plant cells?

Accepted Answer

It is a gelatinous layer rich in pectins that glues adjacent plant cells together.

Question 18

A scientist observes that a certain animal tissue is able to stretch and return to its original shape. Which ECM protein is most likely responsible for this property?

Accepted Answer

Elastin

Question 19

Which of the following best explains why signal deactivation is important in cell signaling pathways?

Accepted Answer

It ensures that the cell remains sensitive to new signals and can rapidly adjust its response.

Cell–Cell Interactions: Structure, Communication, and Signaling

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