Q: Which of the following is an example of a symport carrier?

Na\textsuperscript{+}-glucose (SGLT) transporter

Q: Which of the following transporters is an example of primary active transport?

Na\textsuperscript{+}-K\textsuperscript{+} ATPase

Question 1

Which of the following best describes the difference between facilitated diffusion and active transport across a cell membrane?

Accepted Answer

Facilitated diffusion moves molecules down their concentration gradient without energy input, while active transport moves molecules against their concentration gradient using energy.

Question 2

A patient is given a drug that acts as a competitive inhibitor for the GLUT transporter. Which of the following outcomes is most likely?

Accepted Answer

Glucose transport into cells will decrease because the inhibitor competes for the binding site.

Question 3

Which equation best represents the relationship between substrate concentration and transport rate for carrier-mediated transport, up to the point of saturation?

Accepted Answer

$$v = V_{max} \cdot \frac{[S]}{K_m + [S]}$$

Question 4

Which of the following is an example of a symport carrier?

Accepted Answer

Na	extsuperscript{+}-glucose (SGLT) transporter

Question 5

A cell is observed to transport two different ions in opposite directions using the same carrier protein. What type of carrier is this?

Accepted Answer

Antiport carrier

Question 6

Which of the following statements about carrier proteins is TRUE?

Accepted Answer

Carrier proteins undergo conformational changes to move molecules across the membrane.

Question 7

If the extracellular concentration of glucose increases, what happens to the rate of glucose transport via GLUT carriers, assuming no competitive inhibitors are present?

Accepted Answer

The transport rate increases until all carriers are saturated, then plateaus at the transport maximum.

Question 8

Which process is described as the cell engulfing a bacterium into a vesicle formed by the cytoskeleton?

Accepted Answer

Phagocytosis

Question 9

A mutation causes a carrier protein to lose its ability to change conformation after binding its substrate. What is the most likely consequence?

Accepted Answer

The substrate will not be transported across the membrane.

Question 10

Which of the following best explains why transport rate via carrier proteins reaches a maximum (saturation)?

Accepted Answer

All carrier binding sites are occupied, so no additional substrate can be transported until a site becomes available.

Question 11

Which of the following is NOT a feature of receptor-mediated endocytosis?

Accepted Answer

It is always a nonselective process.

Question 12

Which of the following transporters is an example of primary active transport?

Accepted Answer

Na	extsuperscript{+}-K	extsuperscript{+} ATPase

Question 13

During transcellular transport of glucose in epithelial cells, which sequence of events occurs?

Accepted Answer

Glucose enters the cell via active transport and exits via facilitated diffusion.

Question 14

Which of the following is a consequence of competition between two substrates for the same carrier protein?

Accepted Answer

The transport rate of each substrate decreases compared to when only one is present.

Question 15

Which of the following best describes the role of clathrin in vesicular transport?

Accepted Answer

Clathrin forms coated pits that help in receptor-mediated endocytosis.

Question 16

A cell uses the Na	extsuperscript{+}-glucose symporter to absorb glucose from the intestinal lumen. Which type of transport is this?

Accepted Answer

Secondary active transport

Question 17

Which of the following is TRUE regarding antiport carriers?

Accepted Answer

They move two substrates in opposite directions across the membrane.

Question 18

Which process allows for the movement of substances through the junctions between adjacent epithelial cells?

Accepted Answer

Paracellular transport

Question 19

A researcher observes that the rate of substrate transport by a carrier protein is unaffected by increasing substrate concentration beyond a certain point. What is the most likely explanation?

Accepted Answer

The carrier protein has reached its transport maximum ($$V_{max}).$$

Ch 5b Membrane Transport Dynamics: Carrier-Mediated and Vesicular Transport

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