$$ATP \rightarrow ADP + Pi + \text{energy}$$

Question 1

Which of the following best explains why the surface area-to-volume ratio is critical for cell function?

Accepted Answer

It affects the cell's ability to efficiently exchange materials with its environment.

Question 2

According to the fluid mosaic model, which statement is TRUE about the plasma membrane?

Accepted Answer

Proteins and lipids are embedded in the membrane and can move laterally within the layer.

Question 3

How does the degree of saturation in phospholipid fatty acid tails affect membrane fluidity?

Accepted Answer

Unsaturated fatty acids increase membrane fluidity by preventing tight packing.

Question 4

A cell is placed in a solution with a higher solute concentration than its cytoplasm. What will happen to the cell due to osmosis?

Accepted Answer

Water will move out of the cell, causing it to shrink.

Question 5

Which equation correctly represents the hydrolysis of ATP during active transport?

Accepted Answer

$$ATP ightarrow ADP + Pi + 	ext{energy}$$

Question 6

Which of the following molecules is MOST likely to diffuse directly through the hydrophobic interior of a cell membrane?

Accepted Answer

Propane

Question 7

Facilitated diffusion differs from simple diffusion in that:

Accepted Answer

It uses membrane proteins to transport polar molecules down their concentration gradient.

Question 8

Why do patients with diabetes mellitus often have glucose in their urine?

Accepted Answer

Their blood glucose levels exceed the capacity of kidney carrier proteins to reabsorb glucose.

Question 9

Which of the following best describes osmosis?

Accepted Answer

Movement of water molecules across a semipermeable membrane toward higher solute concentration.

Question 10

What is the main function of the sodium-potassium pump in animal cells?

Accepted Answer

To use ATP to move $$3\ Na^+$$ out and $$2\ K^+ in$$, both against their concentration gradients.

Question 11

Which process involves the cell taking in large particulate matter by engulfing it?

Accepted Answer

Phagocytosis

Question 12

Which of the following is TRUE about channel proteins in the cell membrane?

Accepted Answer

They form hydrophilic tunnels that allow specific molecules to pass through.

Question 13

Which type of cell signaling involves the signaling molecule traveling through the bloodstream to reach distant target cells?

Accepted Answer

Endocrine signaling

Question 14

Which statement best describes the difference between diffusion and osmosis?

Accepted Answer

Diffusion is the movement of solutes down their concentration gradient, while osmosis is the movement of water toward higher solute concentration.

Question 15

Which of the following is a consequence of increasing cholesterol content in the plasma membrane?

Accepted Answer

Membrane fluidity increases by disrupting interactions between phospholipids.

Question 16

A nonpolar signaling molecule such as cortisol will most likely:

Accepted Answer

Pass through the plasma membrane and bind to a cytoplasmic receptor.

Question 17

Which of the following is NOT a type of bulk transport?

Accepted Answer

Facilitated diffusion

Question 18

Which formula best represents the relationship between supply and demand for cell transport?

Accepted Answer

$$	ext{Surface Area} \geq 	ext{Volume}$$

Question 19

Which of the following is a reason why channel proteins can be gated?

Accepted Answer

To allow the cell to control diffusion in response to chemical, electrical, or mechanical stimuli.

Question 20

Which of the following statements about cell walls is correct?

Accepted Answer

Cell walls provide physical restriction, helping plant, fungal, and prokaryotic cells survive osmotic stress.

Cell Membranes and Communication: Structure, Transport, and Signaling

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