Q: Which of the following equations best represents the energy requirement for primary active transport?

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

Question 1

Which of the following best describes the main function of the sodium-potassium pump (Na+-K+ ATPase) in the plasma membrane?

Accepted Answer

It pumps sodium and potassium ions against their concentration gradients using energy from ATP hydrolysis.

Question 2

During the operation of the Na+-K+ pump, how many sodium ions are transported out of the cell for each cycle?

Accepted Answer

$$3$$

Question 3

Which step in the Na+-K+ pump cycle is directly powered by ATP hydrolysis?

Accepted Answer

Phosphorylation of the pump protein, causing a conformational change.

Question 4

A patient is given a drug that inhibits ATP production. Which of the following processes would be most directly affected?

Accepted Answer

Primary active transport of ions across the plasma membrane.

Question 5

Which of the following best explains why the interior of the cell membrane becomes negatively charged during the establishment of the resting membrane potential?

Accepted Answer

Large anions are trapped inside the cell and potassium ions diffuse out.

Question 6

Which of the following is an example of secondary active transport?

Accepted Answer

Glucose being transported into a cell using the sodium gradient established by the Na+-K+ pump.

Question 7

Which process is illustrated by the image showing a cell engulfing a large particle with pseudopods?

Accepted Answer

Phagocytosis

Question 8

Which of the following best describes pinocytosis?

Accepted Answer

The cell 'gulps' extracellular fluid and solutes into small vesicles in a nonspecific manner.

Question 9

Which of the following is NOT a function of vesicular transport?

Accepted Answer

Simple diffusion

Question 10

A neuron maintains a resting membrane potential of $$-70\ \mathrm{mV}. $$Which of the following best explains how this potential is generated and maintained?

Accepted Answer

The Na+-K+ pump moves 3 Na+ out and 2 K+ in, and K+ leaks out of the cell through channels, leaving behind negatively charged proteins.

Question 11

Which of the following best describes receptor-mediated endocytosis?

Accepted Answer

It uses specific receptors to selectively internalize molecules such as hormones and cholesterol.

Question 12

Which of the following scenarios is an example of exocytosis?

Accepted Answer

A neuron releasing neurotransmitters into a synaptic cleft.

Question 13

Which of the following equations best represents the energy requirement for primary active transport?

Accepted Answer

$$\mathrm{ATP} ightarrow \mathrm{ADP} + \mathrm{P_i} + 	ext{energy}$$

Question 14

Which of the following is true regarding the direction of ion movement by the Na+-K+ ATPase?

Accepted Answer

Na+ is pumped out of the cell and K+ is pumped in.

Question 15

A mutation causes the Na+-K+ pump to stop functioning. Which of the following would be the most immediate consequence?

Accepted Answer

The electrochemical gradients for Na+ and K+ would dissipate, affecting nerve and muscle function.

Question 16

Which of the following best describes the role of potassium leakage channels in the resting membrane potential?

Accepted Answer

They allow K+ to diffuse out of the cell, contributing to a negative charge inside.

Question 17

Which of the following processes is most likely to be impaired in a patient with a genetic defect in clathrin protein production?

Accepted Answer

Receptor-mediated endocytosis

Question 18

Which of the following best explains why the Na+-K+ pump is considered an example of primary active transport?

Accepted Answer

It directly uses energy from ATP hydrolysis to move ions against their gradients.

Question 19

Which of the following is a real-life example of transcytosis?

Accepted Answer

Absorption of antibodies from mother’s milk across the infant’s intestinal cells.

Cell Membrane Transport: Active Processes and Membrane Potential

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