Q: Which of the following equations correctly represents the action of the Na+-K+ pump?

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

Question 1

Which of the following best describes the main difference between primary and secondary active transport across the plasma membrane?

Accepted Answer

Primary active transport uses energy directly from ATP hydrolysis, while secondary active transport uses energy indirectly from ionic gradients created by primary active transport.

Question 2

The sodium-potassium pump (Na+-K+ ATPase) is essential for maintaining the resting membrane potential in excitable cells. Which of the following correctly describes its action?

Accepted Answer

It pumps 3 Na+ ions out of the cell and 2 K+ ions into the cell, both against their concentration gradients.

Question 3

Which of the following is NOT a reason why a solute would require active transport to cross the plasma membrane?

Accepted Answer

The solute is able to move down its concentration gradient.

Question 4

A white blood cell engulfs a bacterium by extending pseudopods around it, forming a vesicle that later fuses with a lysosome. This process is best described as:

Accepted Answer

Phagocytosis

Question 5

During the establishment of the resting membrane potential (RMP), which ion is the primary influencer, and what is the typical RMP value in most cells?

Accepted Answer

K+ is the primary influencer, and the RMP is around $$-90\ \mathrm{mV}.$$

Question 6

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

Accepted Answer

K+ diffuses out of the cell through leakage channels, while negatively charged proteins remain inside.

Question 7

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

Accepted Answer

Release of neurotransmitters from a neuron into the synaptic cleft.

Question 8

A cell is exposed to a toxin that inhibits ATP production. Which of the following processes would be most directly affected?

Accepted Answer

Active transport of Na+ and K+ across the plasma membrane.

Question 9

Which of the following statements about vesicular transport is TRUE?

Accepted Answer

It requires ATP and is used to move large particles, macromolecules, and fluids across the membrane.

Question 10

Which of the following best describes the role of G proteins in cell signaling?

Accepted Answer

They act as relays between extracellular first messengers and intracellular second messengers.

Question 11

A patient has a genetic defect that prevents the formation of clathrin-coated pits. Which cellular process would be most directly impaired?

Accepted Answer

Receptor-mediated endocytosis

Question 12

Which of the following equations correctly represents the action of the Na+-K+ pump?

Accepted Answer

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

Question 13

Which of the following best explains why the Na+-K+ pump is considered an antiporter?

Accepted Answer

It moves Na+ and K+ in opposite directions across the membrane.

Question 14

Which of the following is an example of contact signaling in cell-environment interactions?

Accepted Answer

Immune cells recognizing each other by their unique surface membrane receptors.

Question 15

A neuron is at rest with a membrane potential of $$-70\ \mathrm{mV}. If $$the membrane suddenly becomes more permeable to Na+, what will happen to the membrane potential?

Accepted Answer

It will become less negative (depolarize).

Question 16

Which of the following best describes the process of transcytosis?

Accepted Answer

Transport of substances into, across, and then out of a cell.

Question 17

Which of the following is a function of cell adhesion molecules (CAMs) in the glycocalyx?

Accepted Answer

They anchor cells to each other and to the extracellular matrix.

Question 18

Which of the following is a correct statement about the role of second messengers in chemical signaling?

Accepted Answer

Second messengers, such as cyclic AMP or calcium, are released inside the cell in response to activation of G protein–linked receptors.

Active Membrane Transport, Vesicular Transport, and Membrane Potentials in Human Cells

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