Question 1

Which of the following best describes the process of phagocytosis?

Accepted Answer

The cell engulfs large particles such as bacteria by wrapping its membrane around them and forming a vesicle.

Question 2

A patient with familial hypercholesterolemia has defective LDL receptors. Which bulk transport process is directly impaired in this condition?

Accepted Answer

Receptor-mediated endocytosis

Question 3

Which of the following is a key difference between pinocytosis and phagocytosis?

Accepted Answer

Pinocytosis involves the uptake of liquids, while phagocytosis involves the uptake of large particles.

Question 4

In the context of red blood cells, what happens when a cell is placed in a hypotonic solution (as shown in Image A)?

Accepted Answer

Water enters the cell, causing it to swell and potentially burst.

Question 5

Which mechanism would a liver cell use to import glucose when the intracellular concentration is already higher than the extracellular concentration?

Accepted Answer

Active transport using a membrane protein and ATP

Question 6

A red blood cell is placed in a hypertonic solution (as in Image C). What is the direction of water movement and what is the result?

Accepted Answer

Water moves out of the cell, causing it to shrink (crenate).

Question 7

Which of the following best describes exocytosis?

Accepted Answer

A vesicle fuses with the plasma membrane to release its contents outside the cell.

Question 8

Which of the following statements about receptor-mediated endocytosis is correct?

Accepted Answer

It allows the cell to selectively import specific molecules, such as LDL, by binding to receptors on the plasma membrane.

Question 9

A membrane protein forms a pore that allows $$\mathrm{Na^+}$$ ions to cross the membrane. What type of amino acid residues would you expect to find lining the inside of the pore?

Accepted Answer

Hydrophilic and negatively charged residues to interact with $$\mathrm{Na^+}$$ ions

Question 10

Which of the following best explains why active transport is required to move glucose into a liver cell that already has a high internal glucose concentration?

Accepted Answer

Active transport moves molecules against their concentration gradient using energy, such as ATP.

Question 11

Which of the following is a real-life example of receptor-mediated endocytosis?

Accepted Answer

Uptake of LDL cholesterol particles by liver cells

Question 12

In the schematic of a membrane protein forming a pore, what type of amino acid residues would you expect on the outside of the protein (facing the lipid bilayer)?

Accepted Answer

Hydrophobic residues to interact with the lipid tails of the membrane

Question 13

Which process is most likely responsible for a cell 'drinking' extracellular fluid?

Accepted Answer

Pinocytosis

Question 14

A red blood cell is placed in an isotonic solution (as in Image B). What will happen to the cell?

Accepted Answer

There will be no net movement of water, and the cell will maintain its normal shape.

Question 15

Which of the following best describes the direction of $$\mathrm{Na^+}$$ movement through a membrane channel protein?

Accepted Answer

$$\mathrm{Na^+}$$ moves down its electrochemical gradient through the hydrophilic pore.

Question 16

Which of the following scenarios would most likely require exocytosis?

Accepted Answer

A neuron releasing neurotransmitters into a synaptic cleft

Question 17

Which of the following is NOT a form of endocytosis?

Accepted Answer

Exocytosis

Question 18

A cell is observed to engulf a bacterium. Which process is most likely occurring?

Accepted Answer

Phagocytosis

Question 19

Which of the following best explains why the inside of a membrane protein pore is lined with hydrophilic residues?

Accepted Answer

To allow polar or charged molecules, such as $$\mathrm{Na^+}$$, to pass through the membrane

Cell Membrane Transport Mechanisms: Bulk Transport, Osmosis, and Membrane Proteins

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