Question 1

Which of the following best describes the structure shown in the first image (A, B, and C)?

Accepted Answer

A double layer of phospholipids with embedded proteins, forming a selectively permeable membrane.

Question 2

Referencing the second image, what property of phospholipids causes them to form a bilayer in water?

Accepted Answer

Their hydrophilic heads and hydrophobic tails.

Question 3

The third image shows a circular arrangement of phospholipids. What is this structure called, and what is its biological significance?

Accepted Answer

Vesicle; it is used for transporting substances within cells.

Question 4

The fourth image demonstrates the mixing of membrane proteins in a hybrid cell. What does this experiment support?

Accepted Answer

The fluid mosaic model of the cell membrane.

Question 5

In the fifth image, three types of phospholipid movement are shown. Which movement is least likely to occur and why?

Accepted Answer

Flip-flop, because the hydrophobic tail would have to interact with water.

Question 6

Based on the sixth image, how do unsaturated fatty acid tails affect membrane fluidity?

Accepted Answer

They increase fluidity by introducing kinks that prevent tight packing.

Question 7

The seventh image compares two bilayers. Which one would be more fluid at room temperature and why?

Accepted Answer

The bilayer with shorter fatty acid tails, because shorter tails reduce intermolecular interactions.

Question 8

In the eighth image, cholesterol is shown in two different membrane environments. What is cholesterol's role at low temperatures?

Accepted Answer

It increases membrane fluidity by preventing tight packing of phospholipids.

Question 9

Refer to the ninth and eleventh images. What happens to a cell membrane that is too rigid or too fluid?

Accepted Answer

Too rigid: may break; too fluid: won't hold shape.

Question 10

The tenth and twelfth images use cartoons to illustrate membrane fluidity. What do these cartoons represent?

Accepted Answer

The balance between membrane rigidity and flexibility required for proper function.

Question 11

According to the thirteenth image, which molecules can pass directly through the phospholipid bilayer by simple diffusion?

Accepted Answer

Hydrophobic molecules and small uncharged polar molecules.

Question 12

The fourteenth image shows a concentration gradient. What is the driving force for the movement of molecules in this scenario?

Accepted Answer

Chemical (concentration) gradient.

Question 13

The fifteenth image shows a semipermeable membrane with water and sugar molecules. What process is being illustrated?

Accepted Answer

Osmosis.

Question 14

In the sixteenth image, what is the result of diffusion over time?

Accepted Answer

Molecules become evenly distributed across the membrane.

Question 15

The seventeenth image shows an electrical gradient. What is the effect of membrane potential on ion movement?

Accepted Answer

Positive ions are attracted to negative areas and repelled by positive areas.

Question 16

The eighteenth image shows the distribution of Na+ and K+ ions. Which transport protein is responsible for maintaining this gradient?

Accepted Answer

Na+/K+ ATPase (sodium-potassium pump).

Question 17

Based on the nineteenth image, which function is NOT directly related to ion electrochemical gradients?

Accepted Answer

Protein synthesis.

Question 18

The twentieth image shows the movement of molecules across a membrane over time. What type of transport is illustrated?

Accepted Answer

Simple diffusion.

Cell Membrane Structure and Function: Mini-Textbook Study Guide

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