Question 1

Which of the following molecules is most likely to cross the plasma membrane of an erythrocyte via simple diffusion, according to the size, charge, and polarity rules?

Accepted Answer

O$$_2$$

Question 2

A patient with cystic fibrosis has a defective CFTR ion channel. Which process is directly impaired in their sweat glands?

Accepted Answer

Facilitated diffusion of Cl$$^-$$ ions

Question 3

Which of the following best describes the effect of increasing cholesterol content in a cell membrane?

Accepted Answer

Fluidity increases, permeability decreases

Question 4

The sodium-potassium pump moves ions against their concentration gradients. Which equation best represents the energy requirement for this process?

Accepted Answer

$$\Delta G = RT \ln \frac{[Na^+]_{out}}{[Na^+]_{in}} + RT \ln \frac{[K^+]_{in}}{[K^+]_{out}}$$

Question 5

Which of the following is NOT a characteristic of passive membrane transport?

Accepted Answer

Transport against an electrochemical gradient

Question 6

A cell is placed in a solution with a higher concentration of glucose outside than inside. Which transport mechanism will most efficiently move glucose into the cell?

Accepted Answer

Facilitated diffusion via GLUT-1

Question 7

Which of the following statements about gramicidin is correct?

Accepted Answer

It forms an ion channel that increases membrane permeability to ions

Question 8

Which process is illustrated by the engulfment of viral particles by a cell, as shown in the provided images?

Accepted Answer

Endocytosis

Question 9

Which of the following would most likely increase the permeability of a cell membrane to water?

Accepted Answer

Increasing the number of unsaturated fatty acids

Question 10

A cell actively transports Na$$^+$$ out and K$$^+ in $$using ATP. What is the ratio of Na$$^+ to K$^+$$ moved per cycle of the sodium-potassium pump?

Accepted Answer

3 Na$$^+$$ out, 2 K$$^+ in$$

Question 11

Which of the following is a real-world consequence of defective facilitated diffusion in erythrocytes?

Accepted Answer

Impaired glucose uptake

Question 12

Which equation best describes the rate of simple diffusion across a membrane?

Accepted Answer

$$J = P (C_1$ - C_2$)$$

Question 13

Which of the following is true about the permeability of the phospholipid bilayer to ions?

Accepted Answer

Ions require channel proteins for diffusion

Question 14

Which process is responsible for the uptake of extracellular fluid and small molecules by cells, as shown in the pinocytosis image?

Accepted Answer

Pinocytosis

Question 15

Which of the following best explains why large, uncharged polar molecules like glucose cannot cross the membrane by simple diffusion?

Accepted Answer

They are polar and large, violating both the size and polarity rules

Question 16

Which of the following is an example of indirect active transport?

Accepted Answer

Glucose transport coupled to Na$$^+$$ gradient

Question 17

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

It uses carrier proteins to move molecules down their concentration gradient

Question 18

Which of the following would most likely decrease the permeability of a membrane to glycerol?

Accepted Answer

Increasing cholesterol content

Question 19

Which process is illustrated by the release of secretory granules from a cell, as shown in the exocytosis image?

Accepted Answer

Exocytosis

Question 20

A cell is exposed to a toxin that blocks all ATP production. Which transport process would be most affected?

Accepted Answer

Active transport of Na$$^+$$ and K$$^+$$

Membrane Transport Mechanisms in Cell Biology

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