Question 1

Which of the following statements best explains why triacylglycerols are efficient molecules for energy storage in animals?

Accepted Answer

Their carbon atoms are highly reduced, allowing for more energy to be released upon oxidation.

Question 2

A fatty acid with the formula $$\mathrm{C$$_{18}$$H_{34}O_2$}$$ contains how many double bonds?

Accepted Answer

1

Question 3

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

Accepted Answer

Cholesterol increases membrane fluidity by preventing fatty acid chains from packing too closely.

Question 4

Which of the following lipids is a major component of the inner mitochondrial membrane but is absent from the plasma membrane?

Accepted Answer

Cardiolipin

Question 5

A lipid sample has a high saponification value. What does this indicate about the fatty acids in the lipid?

Accepted Answer

They are mostly short-chain fatty acids.

Question 6

Which of the following best explains why soaps can emulsify oils but may precipitate in hard water, while synthetic detergents like SDS do not?

Accepted Answer

Soaps form insoluble salts with calcium and magnesium ions, while SDS does not.

Question 7

Which of the following membrane lipids contains a carbohydrate as part of its structure?

Accepted Answer

Glycoglycerolipid

Question 8

A membrane protein is found to be covalently attached to a glycosylphosphatidylinositol (GPI) anchor. Where would you expect to find this protein in the cell?

Accepted Answer

On the luminal (extracellular) side of the membrane

Question 9

Which of the following changes would increase the melting temperature ($$T_m) of a $$biological membrane?

Accepted Answer

Increasing the proportion of saturated fatty acids

Question 10

A lipid has the formula $$\mathrm{C$$_{n}$$H_{2n-4}O_2$}. $$How many double bonds does it contain?

Accepted Answer

2

Question 11

Which of the following best describes the fluid mosaic model of biological membranes?

Accepted Answer

Membranes are two-dimensional liquids where lipids and proteins can diffuse laterally.

Question 12

Which of the following is a function of lipid rafts in biological membranes?

Accepted Answer

They serve as platforms for cell signaling and protein sorting.

Question 13

A membrane protein is found to have several stretches of highly hydrophobic amino acids. What is the most likely structural feature of this protein?

Accepted Answer

It contains multiple transmembrane α-helices.

Question 14

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

Accepted Answer

Their cis double bonds introduce kinks, preventing tight packing of lipid tails.

Question 15

Which of the following is true regarding the asymmetry of biological membranes?

Accepted Answer

Phosphatidylserine is predominantly found in the inner leaflet.

Question 16

A sample of fat is analyzed and found to have an iodine value of 120. What does this indicate about the fat?

Accepted Answer

It contains a high proportion of unsaturated fatty acids.

Question 17

Which of the following best describes the process of saponification?

Accepted Answer

Hydrolysis of triacylglycerols with a strong base to produce glycerol and fatty acid salts.

Question 18

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

Accepted Answer

Sphingolipids contain a sphingosine backbone instead of glycerol.

Question 19

Which of the following best explains the role of the translocon in membrane protein synthesis?

Accepted Answer

It acts as a protein-conducting channel, facilitating the insertion of hydrophobic protein regions into the bilayer.

Lipids and Biological Membranes: Structure, Properties, and Functions

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