$$\text{Water moves from a region of lower [solute] to a region of higher [solute]}$$

Question 1

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

Accepted Answer

A double layer of phospholipids with proteins and carbohydrates embedded, where both lipids and proteins can move laterally.

Question 2

Which property of phospholipids is most responsible for the formation of the bilayer structure in biological membranes?

Accepted Answer

Their amphipathic nature, having both hydrophobic and hydrophilic regions.

Question 3

A cell membrane is described as 'selectively permeable.' Which of the following molecules would most easily cross the membrane without assistance?

Accepted Answer

Small nonpolar molecules like $$O_2$$ and $$CO_2.$$

Question 4

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 phospholipids.

Question 5

Cholesterol is an important component of animal cell membranes. What is its primary function at moderate temperatures?

Accepted Answer

It reduces phospholipid movement, thereby stabilizing the membrane.

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 hydrophilic and cannot pass through the hydrophobic core of the membrane.

Question 7

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

Accepted Answer

It will gain water and may burst (lyse).

Question 8

Which of the following is an example of active transport?

Accepted Answer

The sodium-potassium pump moving $$Na^+$$ out of and $$K^+$$ into the cell against their concentration gradients.

Question 9

Which equation best represents the movement of water during osmosis across a selectively permeable membrane?

Accepted Answer

$$	ext{Water moves from a region of lower [solute] to a region of higher [solute]}$$

Question 10

Which of the following best describes the function of aquaporins in the plasma membrane?

Accepted Answer

They facilitate the passive movement of water across the membrane.

Question 11

A plant cell in a hypertonic environment will experience which of the following?

Accepted Answer

It will lose water, and the plasma membrane will pull away from the cell wall (plasmolysis).

Question 12

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

It moves substances down their concentration gradient with the help of transport proteins.

Question 13

The sodium-potassium pump is an example of which type of membrane protein function?

Accepted Answer

Active transport

Question 14

Which of the following best describes the role of an electrogenic pump?

Accepted Answer

It creates a voltage difference across the membrane by moving ions.

Question 15

Which process allows a cell to take in large particles such as bacteria?

Accepted Answer

Phagocytosis

Question 16

During synaptic signaling in animal nervous systems, which event occurs first?

Accepted Answer

An electrical signal triggers the release of neurotransmitters from the nerve cell.

Question 17

Which of the following is a correct sequence of events in cell signaling?

Accepted Answer

Reception → Transduction → Response

Question 18

Which type of membrane receptor acts as a 'gate' for ions when a signaling molecule binds?

Accepted Answer

Ligand-gated ion channel

Question 19

In a signal transduction pathway, what is the main advantage of a cascade involving multiple steps?

Accepted Answer

It amplifies the signal, allowing a small number of signaling molecules to produce a large cellular response.

Question 20

Which of the following is an example of long-distance signaling in animals?

Accepted Answer

Endocrine signaling via hormones traveling through the bloodstream

Membrane Transport & Cell Signaling: Structure, Function, and Mechanisms

Study Guide - Practice Questions