Question 1

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

Accepted Answer

Movement of molecules from higher to lower concentration directly across the phospholipid bilayer without energy input.

Question 2

A bacterial cell is placed in a solution with a higher solute concentration than its cytoplasm. Which process is most likely to occur, and what is the consequence?

Accepted Answer

Osmosis of water out of the cell, leading to plasmolysis due to high osmotic pressure.

Question 3

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

It uses specific membrane proteins to move molecules down their concentration gradient.

Question 4

Aquaporins are essential for:

Accepted Answer

Facilitating rapid water transport across the cell membrane.

Question 5

Which equation best represents the relationship between osmotic pressure ($$\Pi$$), solute concentration ($$C$$), gas constant ($$R$$), and temperature ($$T$$)?

Accepted Answer

$$\Pi = CRT$$

Question 6

A cell uses active transport to move sodium ions from a region of low concentration to high concentration. Which of the following is true about this process?

Accepted Answer

It requires energy, usually in the form of ATP.

Question 7

Which scenario best illustrates passive diffusion?

Accepted Answer

Glucose moving through a carrier protein from high to low concentration without ATP.

Question 8

If a cell membrane is impermeable to solutes but permeable to water, what will happen when the cell is placed in a hypertonic solution?

Accepted Answer

Water will move out of the cell, causing plasmolysis.

Question 9

Which of the following is NOT a characteristic of active transport?

Accepted Answer

Occurs directly across the phospholipid bilayer without proteins.

Question 10

A patient is given intravenous fluids with a solute concentration lower than their blood plasma. What is the most likely effect on their red blood cells?

Accepted Answer

Water will enter the cells by osmosis, potentially causing them to swell and burst.

Question 11

Which process is most directly responsible for the rapid movement of water across cell membranes?

Accepted Answer

Aquaporins facilitating water transport.

Question 12

Which of the following would increase the rate of simple diffusion across a cell membrane?

Accepted Answer

Increasing the concentration gradient.

Question 13

A cell is exposed to a toxin that inhibits ATP production. Which transport process will be most affected?

Accepted Answer

Active transport of ions.

Question 14

Which of the following is a similarity between simple diffusion and facilitated diffusion?

Accepted Answer

Both move substances down their concentration gradient without energy input.

Question 15

A cell membrane contains both carrier proteins and channel proteins. Which process is most likely to occur through these proteins?

Accepted Answer

Facilitated diffusion.

Question 16

Which of the following best explains why bacteria can undergo plasmolysis in high osmotic pressure environments?

Accepted Answer

Water leaves the cell due to a higher external solute concentration, causing the cell membrane to shrink away from the cell wall.

Question 17

Which of the following is an example of a molecule that would most likely cross the cell membrane by simple diffusion?

Accepted Answer

Oxygen ($$O_2)$$

Question 18

A cell is placed in an isotonic solution. What will happen to the movement of water across the cell membrane?

Accepted Answer

Water will move in and out at equal rates, resulting in no net change.

Question 19

Which of the following is NOT a form of passive diffusion?

Accepted Answer

Active transport

Transport Mechanisms Across Microbial Cell Membranes

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