Question 1

Which of the following best describes primary active transport?

Accepted Answer

It requires energy directly from ATP hydrolysis to move solutes against their concentration gradient.

Question 2

The sodium-potassium pump is an example of which type of membrane transport?

Accepted Answer

Primary active transport

Question 3

Which of the following conditions would require a cell to use active membrane transport?

Accepted Answer

The solute is too large for channels and not lipid soluble.

Question 4

What is the main function of antiporters in active transport?

Accepted Answer

They move one substance into the cell and a different substance out of the cell.

Question 5

Which equation correctly represents the stoichiometry of the sodium-potassium pump?

Accepted Answer

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

Question 6

Secondary active transport relies on which of the following for its energy source?

Accepted Answer

Energy stored in ionic gradients created by primary active transport

Question 7

A patient is exposed to cholera toxin, which keeps the G protein 'on.' What is the physiological consequence in intestinal cells?

Accepted Answer

Continuous high cAMP levels causing massive loss of salts and water by osmosis

Question 8

Which of the following best explains why the inside of a cell is more negative than the outside at rest?

Accepted Answer

K$$^+$$ diffuses out of the cell, leaving behind negatively charged proteins that cannot cross the membrane.

Question 9

Which of the following is NOT a function of cell adhesion molecules (CAMs)?

Accepted Answer

Facilitating passive diffusion of ions across the membrane

Question 10

Which process is responsible for the uptake of large solid particles such as bacteria by white blood cells?

Accepted Answer

Phagocytosis

Question 11

During receptor-mediated endocytosis, what is the role of clathrin-coated pits?

Accepted Answer

They selectively capture specific molecules bound to receptors for internalization.

Question 12

Which of the following best describes the resting membrane potential (RMP) in most cells?

Accepted Answer

It is typically around $$-90 mV$$, with the inside of the cell more negative than the outside.

Question 13

Which of the following is TRUE regarding the Na$$^+-K$^+$$ pump?

Accepted Answer

It pumps 3 Na$$^+$$ out and 2 K$$^+ in $$per ATP hydrolyzed.

Question 14

Which of the following scenarios would most likely require vesicular transport?

Accepted Answer

Uptake of large macromolecules or fluids via endocytosis

Question 15

Which process is described as 'cell drinking' and involves the nonspecific uptake of extracellular fluid?

Accepted Answer

Pinocytosis

Question 16

What is the effect of opening gated Na$$^+$$ channels in a neuron during an action potential?

Accepted Answer

Na$$^+$$ rushes into the cell, making the inside more positive.

Question 17

Which of the following is a real-world example of receptor-mediated endocytosis?

Accepted Answer

Uptake of low-density lipoproteins (LDL) by liver cells

Question 18

Which equation best represents the electrical potential difference across a cell membrane?

Accepted Answer

$$V_m = V_{inside} - V_{outside}$$

Question 19

Which of the following is NOT a characteristic of symporters?

Accepted Answer

They only transport one type of molecule at a time.

Question 20

Which of the following best explains why the Na$$^+-K$^+$$ pump is essential for excitable cells such as neurons and muscle cells?

Accepted Answer

It maintains the electrochemical gradients necessary for action potentials.

Cellular Transport Mechanisms: Active and Vesicular Transport

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