Q: The Na+/K+ pump moves sodium and potassium ions across the plasma membrane. What is the stoichiometry of ions transported per ATP hydrolyzed?

$3 \text{ Na}^+$ out, $2 \text{ K}^+$ in$

Question 1

Which of the following best explains why the inner mitochondrial membrane contains a higher concentration of proteins compared to the plasma membrane?

Accepted Answer

It contains enzymes essential for ATP production via oxidative phosphorylation.

Question 2

A phospholipid molecule is described as amphipathic. What does this mean?

Accepted Answer

It contains both hydrophilic and hydrophobic regions.

Question 3

Which bond connects the fatty acid tail to the glycerol backbone in a phospholipid?

Accepted Answer

Ester bond

Question 4

How does the presence of unsaturated fatty acid tails affect membrane fluidity?

Accepted Answer

It increases fluidity by introducing kinks that prevent tight packing.

Question 5

A cell is placed in a hypertonic solution. What will happen to the cell?

Accepted Answer

Water will leave the cell, causing it to shrink.

Question 6

Which of the following transport mechanisms requires energy input from ATP hydrolysis?

Accepted Answer

Active transport

Question 7

The Na+/K+ pump moves sodium and potassium ions across the plasma membrane. What is the stoichiometry of ions transported per ATP hydrolyzed?

Accepted Answer

$3 	ext{ Na}^+$ out, $2 	ext{ K}^+$ in$

Question 8

Which of the following best describes the function of tight junctions between epithelial cells?

Accepted Answer

They prevent the movement of substances between adjacent cells.

Question 9

A mutation disrupts the ER retention signal in a protein. What is the most likely consequence?

Accepted Answer

The protein will be secreted from the cell.

Question 10

Which of the following is a function of the smooth endoplasmic reticulum (SER)?

Accepted Answer

Glycogen breakdown and detoxification

Question 11

Which type of cytoskeletal filament is composed of tubulin dimers and is involved in chromosome separation during mitosis?

Accepted Answer

Microtubules

Question 12

What is the role of GTP in microtubule dynamics?

Accepted Answer

GTP binding promotes microtubule polymerization.

Question 13

Which motor protein moves toward the plus end of microtubules and is involved in anterograde transport?

Accepted Answer

Kinesin

Question 14

A patient is treated with taxol, a drug that stabilizes microtubules. What cellular process is most likely to be affected?

Accepted Answer

Cell division (mitosis)

Question 15

Which of the following best describes the 9+2 arrangement in cilia and flagella?

Accepted Answer

Nine doublet microtubules surrounding two singlet microtubules

Question 16

Which process involves the movement of vesicles from the Golgi apparatus to the plasma membrane for secretion?

Accepted Answer

Exocytosis

Question 17

Which protein is responsible for the contraction of muscle cells by interacting with actin filaments?

Accepted Answer

Myosin

Question 18

Which of the following is a real-life example of regulated secretion?

Accepted Answer

Insulin release from pancreatic beta cells in response to glucose

Question 19

Which of the following best describes the function of SNARE proteins in vesicle-mediated transport?

Accepted Answer

They mediate the fusion of vesicles with target membranes.

Question 20

A cell is exposed to a competitive inhibitor of a carrier protein. What is the expected effect on substrate transport?

Accepted Answer

Transport rate will decrease as the inhibitor competes with the substrate for binding.

Cell Biology Exam 2 Study Guide: Membranes, Transport, Endomembrane System, and Cytoskeleton

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