Question 1

Which of the following best describes the Fluid Mosaic Model of the plasma membrane?

Accepted Answer

The membrane is a fluid structure with proteins embedded or attached, allowing lateral movement of components.

Question 2

Which property allows the plasma membrane to regulate the passage of substances into and out of the cell?

Accepted Answer

Selective permeability

Question 3

A red blood cell is placed in a hypertonic solution. What will most likely happen to the cell?

Accepted Answer

It will lose water and crenate (shrink).

Question 4

Which of the following molecules can most easily diffuse through the lipid bilayer of the plasma membrane?

Accepted Answer

O$$_2$$

Question 5

What is the main function of aquaporins in the plasma membrane?

Accepted Answer

Facilitate the diffusion of water across the membrane

Question 6

Which of the following best explains why plant cells do not burst when placed in a hypotonic solution?

Accepted Answer

The cell wall provides structural support and prevents excessive expansion.

Question 7

Facilitated diffusion differs from simple diffusion in that facilitated diffusion:

Accepted Answer

Requires transport proteins to move specific molecules across the membrane.

Question 8

Which of the following is NOT a characteristic of transport proteins used in facilitated diffusion?

Accepted Answer

They catalyze chemical reactions.

Question 9

A patient has a genetic defect in LDL receptor-mediated endocytosis. What is a likely consequence?

Accepted Answer

Cholesterol accumulates in the blood, increasing risk of atherosclerosis.

Question 10

Which process describes the movement of water across a selectively permeable membrane from an area of low solute concentration to high solute concentration?

Accepted Answer

Osmosis

Question 11

Which of the following best describes pinocytosis?

Accepted Answer

The intake of small fluid/solute droplets into the cell, forming vesicles.

Question 12

Which of the following statements about osmoregulation in Paramecium is correct?

Accepted Answer

They use contractile vacuoles to expel excess water gained in a hypotonic environment.

Question 13

Which of the following is a direct result of placing a plant cell in a hypertonic solution?

Accepted Answer

The cell undergoes plasmolysis as the membrane pulls away from the cell wall.

Question 14

Which of the following equations best represents the process of osmosis?

Accepted Answer

$$H_2O$$ moves from an area of low solute concentration to an area of high solute concentration across a selectively permeable membrane.

Question 15

Which of the following is true about exocytosis?

Accepted Answer

It is the process by which cells expel substances using vesicles that fuse with the plasma membrane.

Question 16

A solution is isotonic to a cell if:

Accepted Answer

There is no net movement of water into or out of the cell.

Question 17

Which of the following best explains why ions such as Na$$^+$$ and Cl$$^-$$ cannot easily cross the plasma membrane?

Accepted Answer

They are hydrophilic and cannot pass through the hydrophobic core of the lipid bilayer.

Question 18

Which of the following is a key difference between phagocytosis and receptor-mediated endocytosis?

Accepted Answer

Phagocytosis engulfs large particles non-specifically, while receptor-mediated endocytosis imports specific macromolecules via receptor proteins.

Question 19

Which of the following best describes turgor pressure in plant cells?

Accepted Answer

The pressure exerted by the cell wall against the plasma membrane due to water uptake.

Plasma Membrane Structure and Function: Transport Mechanisms and Cell Survival

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