Question 1

Why are individuals with fewer LDL cholesterol receptors on their cell membranes at a higher risk for developing cardiovascular disease?

Accepted Answer

They cannot efficiently remove LDL cholesterol from the bloodstream, resulting in higher blood cholesterol levels.

Question 2

A cancer cell is found to be resistant to paclitaxel treatment. Which membrane transport process is most likely responsible for this resistance?

Accepted Answer

Active transport via ATP-driven efflux pumps

Question 3

In the experiment described, which set of cells (A or B) is most likely to be resistant to paclitaxel, and what evidence supports this conclusion?

Accepted Answer

Set B, because they show lower accumulation of paclitaxel, indicating active drug efflux.

Question 4

Imatinib and nilotinib are tested for their ability to overcome cancer cell resistance to paclitaxel. Which result would BEST indicate that these drugs are effective at inhibiting the efflux pump?

Accepted Answer

A significant increase in intracellular paclitaxel concentration after treatment with imatinib or nilotinib.

Question 5

Which of the following best describes the mechanism by which cocaine leads to abnormal neurotransmitter accumulation in the synaptic cleft?

Accepted Answer

Cocaine inhibits the reuptake transporters, preventing neurotransmitter removal from the synaptic cleft.

Question 6

Which type of membrane transport is directly powered by ATP hydrolysis?

Accepted Answer

Active transport

Question 7

A patient is given a drug that inhibits the function of ATP-driven efflux pumps in cancer cells. What is the expected effect on the intracellular concentration of chemotherapeutic agents?

Accepted Answer

It will increase because the drug cannot be pumped out.

Question 8

Which equation best represents the energy requirement for moving a solute against its concentration gradient during active transport?

Accepted Answer

$$ \Delta G = RT \ln \left( \frac{[C]_2}{[C]_1} \right) + zF\Delta \Psi $$

Question 9

Which of the following scenarios best illustrates facilitated diffusion?

Accepted Answer

Glucose entering a cell through a specific transporter protein down its concentration gradient.

Question 10

Jordan, a patient who abused cocaine, is experiencing rapid heartbeat and mood swings. Which neurotransmitter is most likely accumulating in the synaptic cleft due to cocaine's effect?

Accepted Answer

Dopamine

Question 11

Which of the following is NOT a characteristic of active transport across the plasma membrane?

Accepted Answer

It only occurs when the concentration gradient favors movement.

Question 12

A new drug is designed to block the reuptake of serotonin in the brain. What is the likely effect of this drug on synaptic transmission?

Accepted Answer

Increased serotonin levels in the synaptic cleft, enhancing neurotransmission.

Question 13

Which of the following best explains why some cancer cells can survive chemotherapy by 'pumping out' drugs?

Accepted Answer

They express high levels of ATP-dependent efflux transporters that actively remove drugs from the cytoplasm.

Question 14

Which process is most directly responsible for the movement of water across the plasma membrane in response to solute concentration differences?

Accepted Answer

Osmosis

Question 15

A patient with a genetic mutation resulting in nonfunctional LDL receptors is likely to have which of the following blood test results?

Accepted Answer

Elevated LDL cholesterol levels

Question 16

Which of the following is a real-world example of bulk transport across the plasma membrane?

Accepted Answer

A white blood cell engulfing a bacterium via phagocytosis.

Question 17

If a drug inhibits the sodium-potassium pump ($$ \mathrm{Na^+/K^+} -$$ATPase), what is the immediate effect on the cell's membrane potential?

Accepted Answer

The membrane potential becomes less negative (depolarizes).

Question 18

Which of the following best describes the difference between simple diffusion and facilitated diffusion?

Accepted Answer

Facilitated diffusion requires a membrane protein, while simple diffusion does not.

Question 19

A cancer cell line is treated with paclitaxel and nilotinib. The intracellular concentration of paclitaxel increases significantly. What does this suggest about nilotinib's mechanism of action?

Accepted Answer

Nilotinib inhibits the efflux pump responsible for paclitaxel removal.

Question 20

Which of the following best explains why understanding membrane transport is crucial for developing effective drug therapies for addiction and cancer?

Accepted Answer

Drugs often target or are affected by specific transport mechanisms, influencing their efficacy and side effects.

Membrane Transport: Implications for Disease, Cancer Therapy, and Drug Addiction

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