Question 1

Which of the following best describes the 'fluid mosaic model' of the plasma membrane?

Accepted Answer

A flexible layer of phospholipids with proteins and carbohydrates embedded and moving laterally.

Question 2

Which of the following changes would most likely increase the fluidity of a cell membrane at low temperatures?

Accepted Answer

Increasing the proportion of unsaturated fatty acids in the phospholipids.

Question 3

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

Accepted Answer

It will swell and possibly burst as water enters the cell.

Question 4

Which of the following molecules is most likely to diffuse directly through the lipid bilayer of a plasma membrane?

Accepted Answer

Oxygen (O$$_2)$$

Question 5

Facilitated diffusion differs from simple diffusion in that facilitated diffusion:

Accepted Answer

Requires membrane proteins to transport certain molecules.

Question 6

Which of the following best explains why ions such as Na$$^+$$ and K$$^+$$ require transport proteins to cross the plasma membrane?

Accepted Answer

They are charged and cannot pass through the hydrophobic core of the membrane.

Question 7

A cell uses a sodium-potassium pump to move Na$$^+$$ out and K$$^+ in. $$Which of the following statements is correct?

Accepted Answer

ATP is required because both ions are moved against their concentration gradients.

Question 8

Which of the following scenarios is an example of cotransport?

Accepted Answer

A glucose molecule is transported into a cell using the energy from Na$$^+$$ moving down its gradient.

Question 9

Which process is responsible for the uptake of large particles, such as bacteria, by white blood cells?

Accepted Answer

Phagocytosis

Question 10

A plant cell is placed in a hypertonic solution. What is the most likely outcome?

Accepted Answer

The cell will become plasmolyzed as water leaves.

Question 11

Which of the following best describes the role of cholesterol in the plasma membrane?

Accepted Answer

It increases membrane fluidity at high temperatures and prevents solidification at low temperatures.

Question 12

Which of the following is NOT a form of active transport?

Accepted Answer

Facilitated diffusion

Question 13

Which statement about osmosis is correct?

Accepted Answer

Osmosis is the movement of water from low to high solute concentration.

Question 14

A cell is placed in an isotonic solution. What will happen to the cell?

Accepted Answer

It will remain the same size as water moves in and out equally.

Question 15

Which of the following is a function of glycoproteins in the plasma membrane?

Accepted Answer

Acting as receptors for cell signaling

Question 16

Which of the following best explains why water can move through the plasma membrane by both simple diffusion and facilitated diffusion?

Accepted Answer

Water is small enough to pass through the bilayer, but also uses aquaporins for faster movement.

Question 17

Which of the following is true about gated ion channels?

Accepted Answer

They open or close in response to specific stimuli such as chemicals or voltage changes.

Question 18

Which process is used by cells to secrete large molecules, such as hormones, out of the cell?

Accepted Answer

Exocytosis

Question 19

A scientist observes that a certain molecule cannot cross the plasma membrane unless ATP is present. Which type of transport is most likely involved?

Accepted Answer

Active transport

Question 20

Which of the following best describes receptor-mediated endocytosis?

Accepted Answer

The cell takes in specific molecules after they bind to receptors on the membrane.

Membrane Structure and Function: Study Notes for General Biology

Guida di studio - Domande di pratica