Question 1

Which of the following best describes facilitated diffusion across a cell membrane?

Accepted Answer

Movement of molecules down their concentration gradient via specific membrane proteins, without energy input.

Question 2

A red blood cell is placed in a hypertonic solution. What will happen to the cell?

Accepted Answer

It will shrink as water leaves the cell.

Question 3

Which of the following molecules can most easily cross a cell membrane via simple diffusion?

Accepted Answer

Oxygen ($$\mathrm{O_2$})$$

Question 4

Which equation best represents the relationship between the rate of facilitated diffusion ($$J) $$and substrate concentration ($$[S]) $$when all transporters are saturated?

Accepted Answer

$$J = J_{max}$$

Question 5

Which of the following is NOT a function of channel proteins in the cell membrane?

Accepted Answer

Actively pumping solutes against their concentration gradient using ATP.

Question 6

A cell uses the sodium-potassium pump to maintain ion gradients. Which type of transport is this?

Accepted Answer

Primary active transport

Question 7

Which of the following statements about osmosis is correct?

Accepted Answer

Osmosis is the movement of water across a semipermeable membrane from an area of low solute concentration to high solute concentration.

Question 8

Which scenario best describes indirect (secondary) active transport?

Accepted Answer

A glucose molecule is transported into the cell using a pre-established sodium ion gradient.

Question 9

A competitive inhibitor affects enzyme kinetics by:

Accepted Answer

Increasing the $$K_m$$ value, requiring a higher substrate concentration to reach half-maximal velocity.

Question 10

Which of the following is a difference between carrier proteins and channel proteins?

Accepted Answer

Carrier proteins transport molecules by changing shape, while channel proteins form open pores for passive movement.

Question 11

Which of the following would most likely increase the rate of simple diffusion of a nonpolar molecule across a cell membrane?

Accepted Answer

Increasing the concentration gradient of the molecule.

Question 12

Which of the following best explains why facilitated diffusion reaches a maximum rate ($$V_{max}) as $$substrate concentration increases?

Accepted Answer

All available transport proteins become saturated and cannot transport additional molecules faster.

Question 13

Which of the following is a polar molecule that cannot cross the cell membrane via simple diffusion?

Accepted Answer

Water ($$\mathrm{H_2O})$$

Question 14

Which of the following is true about symporters?

Accepted Answer

They transport two different solutes in the same direction across the membrane.

Question 15

A cell is placed in an isotonic solution. What will happen to the cell?

Accepted Answer

It will remain the same size.

Question 16

Which of the following is a correct statement about primary active transport?

Accepted Answer

It uses ATP directly to move molecules against their concentration gradient.

Question 17

Which of the following would NOT be considered a nonpolar molecule capable of simple diffusion?

Accepted Answer

Calcium ion ($$\mathrm{Ca$$^{2+}$$})$$

Question 18

Which of the following best describes the role of ATP in active transport?

Accepted Answer

ATP is hydrolyzed to provide energy for moving molecules against their concentration gradient.

Question 19

Which of the following is true about the movement of ions through gated channel proteins?

Accepted Answer

Ions move down their concentration gradient when the channel is open.

Question 20

Which of the following is a correct example of direct active transport?

Accepted Answer

The sodium-potassium pump hydrolyzes ATP to move $$\mathrm{Na^+}$$ and $$\mathrm{K^+}$$ ions against their gradients.

Membrane Transport Mechanisms in Cell Biology

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