Question 1

Which of the following best describes the structure of the plasma membrane and its role in regulating the movement of substances in and out of the cell?

Accepted Answer

The plasma membrane is a fluid mosaic of phospholipids, proteins, and cholesterol, which selectively allows certain molecules to cross based on size, polarity, and charge.

Question 2

Which factor would most likely increase the fluidity of a cell’s plasma membrane?

Accepted Answer

Increasing the proportion of unsaturated fatty acids and cholesterol in the membrane.

Question 3

A red blood cell placed in a hypertonic solution will:

Accepted Answer

Lose water and shrivel.

Question 4

Which of the following molecules would most easily cross the plasma membrane by simple diffusion?

Accepted Answer

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

Question 5

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

Accepted Answer

$$\mathrm{3Na^+_{in} + 2K^+_{out} + ATP \rightarrow 3Na^+_{out} + 2K^+_{in} + ADP + P_i}$$

Question 6

Which of the following is NOT a characteristic of facilitated diffusion?

Accepted Answer

It requires ATP for transport.

Question 7

A plant cell exposed to a hypotonic solution will:

Accepted Answer

Become turgid.

Question 8

Which of the following best describes receptor-mediated endocytosis?

Accepted Answer

The cell uses specific receptors to bind and internalize particular molecules via coated vesicles.

Question 9

Which of the following statements about exocytosis is correct?

Accepted Answer

Exocytosis involves the fusion of vesicles with the plasma membrane to release large molecules outside the cell.

Question 10

Which of the following best explains why individuals with fewer LDL receptors are at higher risk for cardiovascular disease?

Accepted Answer

They have reduced ability to remove LDL cholesterol from the bloodstream, leading to accumulation in blood vessels.

Question 11

Which of the following is a real-world example of active transport?

Accepted Answer

Glucose moving into a liver cell against its concentration gradient using ATP.

Question 12

Which of the following best describes the difference between phagocytosis and pinocytosis?

Accepted Answer

Phagocytosis is the uptake of solid particles, while pinocytosis is the uptake of liquid droplets.

Question 13

Which of the following best explains the effect of eating a salty meal on blood osmolarity?

Accepted Answer

Your blood becomes hypertonic, causing water to move from tissues into the bloodstream.

Question 14

Which of the following is true about the lining of a membrane protein pore that transports $$\mathrm{Na^+}$$ ions?

Accepted Answer

The inside of the pore is hydrophilic to allow passage of charged ions, while the outside is hydrophobic to interact with membrane lipids.

Question 15

Which of the following best describes the difference between simple diffusion and facilitated diffusion as shown in the graph?

Accepted Answer

Simple diffusion rate increases linearly with concentration, while facilitated diffusion rate plateaus due to protein saturation.

Question 16

Which of the following statements about bulk transport is correct?

Accepted Answer

Bulk transport includes exocytosis and endocytosis, both of which require energy and use vesicles to move large molecules across the membrane.

Question 17

A cancer cell is able to pump out a chemotherapeutic drug against its concentration gradient. Which type of transport is this?

Accepted Answer

Active transport

Question 18

Which of the following would help a plant cell compensate for excessive membrane fluidity during prolonged exposure to high temperature?

Accepted Answer

Alter the lipid composition to have longer fatty acyl tails and fewer double bonds.

Question 19

Which statement best describes the operation of the sodium-potassium pump?

Accepted Answer

It moves $$\mathrm{Na^+}$$ out and $$\mathrm{K^+} in $$against their concentration gradients using ATP.

Membrane Transport and Lipid Structure: Step-by-Step Study Guidance

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