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

Question 1

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

Accepted Answer

A dynamic bilayer of amphipathic lipids with proteins and some carbohydrates embedded or attached, allowing lateral movement.

Question 2

What property of phospholipids is essential for the formation of biological membranes?

Accepted Answer

Their amphipathic nature, having both hydrophobic and hydrophilic regions.

Question 3

Which type of molecule can most easily cross the plasma membrane without assistance?

Accepted Answer

Hydrophobic (nonpolar) molecules like $$O_2$$ and $$CO_2.$$

Question 4

How does cholesterol affect membrane fluidity at moderate temperatures?

Accepted Answer

It decreases fluidity by restraining phospholipid movement.

Question 5

A cell is placed in a hypotonic solution. What is the most likely outcome for an animal cell?

Accepted Answer

The cell will gain water and may burst (lyse).

Question 6

Which membrane protein function is directly involved in cell-to-cell recognition?

Accepted Answer

Binding to specific molecules on the extracellular surface, often via glycoproteins.

Question 7

Facilitated diffusion differs from simple diffusion in that:

Accepted Answer

Facilitated diffusion uses transport proteins to move substances down their concentration gradient.

Question 8

Which equation best represents the movement of water during osmosis?

Accepted Answer

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

Question 9

What is the primary role of the sodium-potassium pump in animal cells?

Accepted Answer

To actively transport $$Na^+$$ out of the cell and $$K^+$$ into the cell, maintaining membrane potential.

Question 10

Which process allows large molecules like polysaccharides to exit the cell in bulk?

Accepted Answer

Exocytosis.

Question 11

A plant cell in a hypertonic environment will most likely:

Accepted Answer

Lose water, causing the membrane to pull away from the cell wall (plasmolysis).

Question 12

Which type of membrane protein is most likely to be involved in signal transduction?

Accepted Answer

Transmembrane proteins that can bind signaling molecules and initiate cellular responses.

Question 13

Which of the following is an example of local signaling in animal cells?

Accepted Answer

Synaptic signaling involving neurotransmitters released at a synapse.

Question 14

What is the main difference between channel proteins and carrier proteins in facilitated diffusion?

Accepted Answer

Channel proteins provide corridors for molecules to pass, while carrier proteins change shape to move molecules across.

Question 15

Which equation describes the direction of solute movement in passive diffusion?

Accepted Answer

$$	ext{Solute moves from an area of high concentration to low concentration}$$

Question 16

Which process is directly responsible for the amplification of a signal inside a cell after reception?

Accepted Answer

A cascade of protein interactions in the signal transduction pathway.

Question 17

Which of the following best explains why unsaturated fatty acid tails increase membrane fluidity?

Accepted Answer

The kinks in unsaturated tails prevent tight packing, increasing movement.

Question 18

Which type of endocytosis is most specific for the uptake of certain molecules?

Accepted Answer

Receptor-mediated endocytosis.

Question 19

What is the main function of an electrogenic pump in the plasma membrane?

Accepted Answer

To generate voltage across the membrane by moving ions.

Question 20

Which of the following is a correct sequence for cell signaling?

Accepted Answer

Reception → Transduction → Response

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

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