Question 1

Which of the following best describes the amphipathic nature of phospholipids in the plasma membrane?

Accepted Answer

Phospholipids have both hydrophilic and hydrophobic regions, allowing them to form a bilayer in aqueous environments.

Question 2

Which type of fatty acid is most likely to increase the risk of coronary heart disease (CHD) due to its effect on blood cholesterol levels?

Accepted Answer

Trans unsaturated fatty acids

Question 3

A patient has high levels of LDL and low levels of HDL in their blood. What is the most likely consequence?

Accepted Answer

Increased risk of coronary heart disease

Question 4

Which of the following is NOT a function of the plasma membrane?

Accepted Answer

Energy production

Question 5

What is the main structural difference between saturated and unsaturated fatty acids?

Accepted Answer

Unsaturated fatty acids have one or more double bonds, causing kinks in their structure.

Question 6

Which equation correctly represents the formation of a triglyceride from its components?

Accepted Answer

$$\mathrm{Glycerol} + 3\ \mathrm{Fatty\ Acids} \rightarrow \mathrm{Triglyceride} + 3\ \mathrm{H_2O}$$

Question 7

Which statement best explains why cholesterol is important in the plasma membrane?

Accepted Answer

Cholesterol stabilizes the membrane and prevents it from solidifying at low temperatures.

Question 8

Which of the following transport processes requires energy input from the cell?

Accepted Answer

Active transport

Question 9

A researcher observes that a certain molecule can cross the plasma membrane only with the help of a specific protein, but no energy is required. What type of transport is this?

Accepted Answer

Facilitated diffusion

Question 10

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

Accepted Answer

A dynamic bilayer of phospholipids with proteins and other molecules scattered throughout, allowing lateral movement

Question 11

Which of the following statements about lipoproteins is correct?

Accepted Answer

LDL carries cholesterol from the liver to the body, raising blood cholesterol levels.

Question 12

Which membrane component is primarily responsible for cell-to-cell recognition?

Accepted Answer

Glycolipids

Question 13

Which of the following is a correct statement about passive transport across the plasma membrane?

Accepted Answer

Passive transport moves molecules from high to low concentration without energy input.

Question 14

A mutation causes a cell to produce nonfunctional channel proteins in its plasma membrane. Which process would be most directly affected?

Accepted Answer

Facilitated diffusion of ions

Question 15

Which of the following best explains why trans fats are considered more harmful than saturated fats?

Accepted Answer

Trans fats raise LDL and lower HDL levels, greatly increasing blood cholesterol.

Question 16

Which of the following equations best represents the direction of active transport for sodium and potassium ions in the Na+/K+ pump?

Accepted Answer

$$3\ \mathrm{Na^+}_{\mathrm{inside}} \rightarrow 3\ \mathrm{Na^+}_{\mathrm{outside}}$$ and $$2\ \mathrm{K^+}_{\mathrm{outside}} \rightarrow 2\ \mathrm{K^+}_{\mathrm{inside}}$$

Question 17

Which of the following factors should be considered when evaluating health claims about lipids and coronary heart disease?

Accepted Answer

Genetic factors, cohort size, study duration, and all dietary components

Question 18

Which of the following statements about the movement of molecules across the plasma membrane is correct?

Accepted Answer

Hydrophobic molecules can pass through the lipid bilayer more easily than hydrophilic molecules.

Question 19

Which of the following best describes the role of integral proteins in the plasma membrane?

Accepted Answer

They are embedded within the membrane and primarily function in transport.

11-Lipids and the Plasma Membrane: Structure, Function, and Transport

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