Question 1

Which of the following best explains why saturated fatty acids have higher melting temperatures than unsaturated fatty acids?

Accepted Answer

Saturated fatty acids pack more tightly due to their straight chains, maximizing van der Waals interactions and requiring more energy to disrupt.

Question 2

A membrane lipid is described as having a glycerol backbone, two fatty acid tails, and a phosphate group attached to the third carbon. What class of lipid is this?

Accepted Answer

Glycerophospholipid

Question 3

Which of the following changes would most likely increase the fluidity of a biological membrane at room temperature?

Accepted Answer

Increasing the proportion of unsaturated (especially polyunsaturated) fatty acids in membrane lipids

Question 4

Which of the following best describes the amphipathic nature of membrane lipids?

Accepted Answer

They contain both hydrophobic tails and hydrophilic head groups.

Question 5

A patient is found to have high levels of trans fatty acids in their blood. Which of the following is a likely consequence?

Accepted Answer

Increased risk of cardiovascular disease due to tighter packing of trans fats in membranes

Question 6

Which of the following is the correct shorthand nomenclature for a fatty acid with 18 carbons and one double bond at the 9th carbon (counting from the carboxyl end)?

Accepted Answer

$$18:1(\$$Delta^9$$)$$

Question 7

Which of the following membrane lipids is a major component of lipid rafts and helps buffer membrane fluidity in animal cells?

Accepted Answer

Cholesterol

Question 8

Which of the following statements about glycosphingolipids is TRUE?

Accepted Answer

They contain a sphingosine backbone and are important for cell surface recognition, such as blood group antigens.

Question 9

Which of the following best describes the effect of cholesterol on membrane fluidity at physiological temperatures?

Accepted Answer

Cholesterol buffers membrane fluidity, making membranes less sensitive to temperature changes.

Question 10

A lipid molecule is described as having a sphingosine backbone, a fatty acid attached via an amide bond, and a phosphocholine head group. What type of lipid is this?

Accepted Answer

Sphingomyelin

Question 11

Which of the following is a biological role of omega-3 fatty acids such as EPA and DHA?

Accepted Answer

They have been correlated with cardiovascular health benefits.

Question 12

Which of the following best explains why micelles form in water when detergents are added?

Accepted Answer

Detergents are amphipathic molecules that spontaneously aggregate with hydrophobic tails sequestered in the interior, minimizing unfavorable interactions with water.

Question 13

Which of the following is TRUE regarding the asymmetric distribution of membrane lipids?

Accepted Answer

Specialized transport proteins catalyze the movement of lipids between leaflets, maintaining asymmetry.

Question 14

A membrane protein is found to be anchored to the cytoskeleton. What effect does this have on its mobility within the membrane?

Accepted Answer

Its lateral mobility is restricted due to anchoring.

Question 15

Which of the following is the correct shorthand for eicosapentaenoic acid (EPA), an omega-3 fatty acid with 20 carbons and 5 double bonds at positions 5, 8, 11, 14, and 17?

Accepted Answer

$$20:5(\$$Delta^{5,8,11,14,17}$$)$$

Question 16

Which of the following statements about membrane lipid movement is CORRECT?

Accepted Answer

Lateral diffusion of lipids within the same leaflet is rapid and uncatalyzed.

Question 17

Which of the following is a distinguishing feature of sphingolipids compared to glycerophospholipids?

Accepted Answer

Sphingolipids contain a sphingosine backbone and no glycerol.

Question 18

A cell is exposed to low temperatures. Which of the following adaptations would help maintain membrane fluidity?

Accepted Answer

Increasing the proportion of unsaturated fatty acids in membrane lipids

Question 19

Which of the following is TRUE about the biological roles of membrane lipids?

Accepted Answer

They form barriers that separate cellular compartments and participate in cell signaling.

Lipids and Biological Membranes: Structure, Function, and Diversity

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