Question 1

Which of the following molecules is most likely to pass freely through the phospholipid bilayer without the aid of a transport protein?

Accepted Answer

Carbon dioxide ($$\mathrm{CO_2$})$$

Question 2

A cell is placed in a solution containing a high concentration of potassium ions ($$\mathrm{K^+}) $$outside and a low concentration inside. If the cell wants to move $$\mathrm{K^+}$$ into the cytoplasm against its concentration gradient, which process will it use?

Accepted Answer

Active transport

Question 3

Which statement best describes passive transport across a membrane?

Accepted Answer

It is a random process that moves molecules from high to low concentration.

Question 4

The sodium-glucose pump in the gut moves sodium ions ($$\mathrm{Na^+}) $$and glucose into the cell. If glucose is moved against its concentration gradient, what type of transport is this?

Accepted Answer

Active transport

Question 5

Which of the following properties would you expect in a molecule that can pass freely through the phospholipid bilayer?

Accepted Answer

Small and uncharged

Question 6

A cell uses the PMCA pump to move calcium ions ($$\mathrm{Ca$$^{2+}$$}) $$out of the cytoplasm. This process requires ATP. Which equation best represents the energy usage in this process?

Accepted Answer

$$\mathrm{ATP \rightarrow ADP + P_i}$$

Question 7

Which of the following is NOT a function of biological membranes?

Accepted Answer

Synthesizing proteins

Question 8

Bulk flow is best described as:

Accepted Answer

Transport of large cargo in vesicles across the membrane

Question 9

Which of the following statements about facilitated diffusion is TRUE?

Accepted Answer

It requires a transport protein but does not require energy input.

Question 10

A patient has a genetic defect in the sodium-potassium pump. Which of the following consequences is most likely?

Accepted Answer

Impaired ability to maintain proper ion gradients across the cell membrane

Question 11

Which of the following is a source of energy that can be used to drive active transport across membranes?

Accepted Answer

ATP hydrolysis

Question 12

Which of the following molecules would require a transport protein to cross the membrane?

Accepted Answer

Sodium ion ($$\mathrm{Na^+})$$

Question 13

Which process is described by the movement of molecules from an area of high concentration to an area of low concentration, without energy input?

Accepted Answer

Simple diffusion

Question 14

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

Accepted Answer

Active transport

Question 15

Which of the following best explains why ions such as $$\mathrm{Na^+}$$ and $$\mathrm{K^+}$$ cannot freely cross the phospholipid bilayer?

Accepted Answer

They are charged and hydrophilic.

Question 16

Which of the following scenarios illustrates the concept of selective permeability?

Accepted Answer

A membrane allows water and oxygen to pass but blocks glucose and sodium ions.

Question 17

Which of the following is TRUE about the movement of molecules by simple diffusion?

Accepted Answer

It is driven by the intrinsic kinetic energy of molecules.

Question 18

A researcher observes that glucose enters a cell more rapidly when a specific protein is present in the membrane. What type of transport is most likely occurring?

Accepted Answer

Facilitated diffusion

Question 19

Which of the following best describes the role of chemical gradients in membrane transport?

Accepted Answer

They provide the energy for passive movement of molecules.

Question 20

Which of the following is an example of a multi-step transport process involving both passive and active mechanisms?

Accepted Answer

Sodium ions entering a cell via facilitated diffusion and then being pumped out by the sodium-potassium pump using ATP

Membrane Transport in Cells: Mechanisms and Principles

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