Question 1

Which of the following statements best explains why lipids are not considered polymers?

Accepted Answer

Lipids are not formed from repeating monomers; instead, they are assembled from smaller molecules like glycerol and fatty acids.

Question 2

Which type of chemical reaction is responsible for forming triglycerides from glycerol and fatty acids?

Accepted Answer

Dehydration reaction

Question 3

What is the primary reason that saturated fatty acids are solid at room temperature?

Accepted Answer

Their hydrocarbon chains are completely saturated with hydrogens, allowing them to pack tightly together.

Question 4

Which of the following best describes the structure of a phospholipid?

Accepted Answer

A molecule with a polar head group, two fatty acid tails, and a phosphate group attached to glycerol

Question 5

Why do phospholipids spontaneously form bilayers in aqueous solutions?

Accepted Answer

Because their amphipathic nature causes hydrophilic heads to interact with water and hydrophobic tails to avoid water

Question 6

Which of the following equations correctly represents the formation of a triglyceride from glycerol and three fatty acids?

Accepted Answer

$$\mathrm{glycerol} + 3\ \mathrm{fatty\ acids} \rightarrow \mathrm{triglyceride} + 3\ \mathrm{H_2O}$$

Question 7

A cell is placed in a hypertonic solution. What will happen to the cell?

Accepted Answer

The cell will lose water and shrink.

Question 8

Which of the following factors increases the permeability of a phospholipid bilayer?

Accepted Answer

Short, unsaturated hydrocarbon tails

Question 9

What is the main function of cholesterol in animal cell membranes?

Accepted Answer

It stabilizes membrane fluidity across temperature changes.

Question 10

Which of the following best describes facilitated diffusion?

Accepted Answer

Movement of molecules from high to low concentration through membrane proteins without energy input

Question 11

A mutation causes the sodium-potassium pump to stop functioning in a neuron. What is the most likely consequence?

Accepted Answer

The neuron will be unable to maintain its membrane potential.

Question 12

Which of the following equations represents the net movement of water during osmosis when a cell is placed in a hypotonic solution?

Accepted Answer

$$\mathrm{H_2O_{outside}} \rightarrow \mathrm{H_2O_{inside}}$$

Question 13

Which of the following is true about membrane proteins?

Accepted Answer

Transmembrane proteins are amphipathic, with hydrophilic and hydrophobic regions.

Question 14

Which process requires energy input from ATP to move molecules against their concentration gradient?

Accepted Answer

Active transport

Question 15

A patient with cystic fibrosis has a defective chloride ion channel. What is the direct consequence of this defect?

Accepted Answer

Water cannot leave the cell by osmosis, resulting in thick mucus.

Question 16

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

Accepted Answer

Phospholipids and proteins move laterally within the bilayer, creating a dynamic structure.

Question 17

Which of the following is a correct statement about the permeability of phospholipid bilayers?

Accepted Answer

Small, nonpolar molecules have high permeability across the bilayer.

Question 18

Which of the following is an example of secondary active transport?

Accepted Answer

Movement of glucose into a cell using the sodium gradient established by the Na+/K+ ATPase

Question 19

Which of the following best explains why unsaturated fatty acids tend to be liquid at room temperature?

Accepted Answer

They have double bonds that create kinks, preventing tight packing.

Lipids and Membrane Structure: Chapter 6 Study Notes

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