Question 1

Which of the following statements best explains why fats are a more efficient form of energy storage than polysaccharides in animals?

Accepted Answer

Fats are more reduced and nonpolar, allowing them to store more energy per carbon and less water per gram.

Question 2

A fatty acid described as 18:1(Δ9) is best characterized by which of the following?

Accepted Answer

It has 18 carbons and one double bond at the 9th carbon from the carboxyl group.

Question 3

Which structural feature distinguishes sphingolipids from glycerophospholipids?

Accepted Answer

Sphingolipids contain a sphingosine backbone and an amide linkage to a fatty acid.

Question 4

Which of the following best describes the effect of cis double bonds in unsaturated fatty acids on membrane fluidity?

Accepted Answer

Cis double bonds introduce kinks, preventing tight packing and increasing membrane fluidity.

Question 5

Which of the following is a function of waxes in biological systems?

Accepted Answer

They provide waterproofing and protection from evaporation in plants and animals.

Question 6

Which of the following statements about omega-3 fatty acids is correct?

Accepted Answer

Alpha-linolenic acid (ALA) is an essential omega-3 fatty acid that can be converted to EPA and DHA.

Question 7

Which of the following best explains why trans fatty acids are associated with increased cardiovascular risk?

Accepted Answer

Trans fatty acids pack more regularly, raising melting points and promoting plaque formation in arteries.

Question 8

Which of the following is true regarding the degradation of structural and signaling lipids in cells?

Accepted Answer

Phospholipids are degraded by specific phospholipases, and improper degradation of gangliosides can lead to lysosomal storage disorders.

Question 9

Which of the following is a major component of most eukaryotic cell membranes but is absent in many prokaryotes such as E. coli?

Accepted Answer

Phosphatidylcholine

Question 10

A triacylglycerol molecule consists of:

Accepted Answer

Three fatty acids esterified to a glycerol molecule.

Question 11

Which of the following equations correctly represents the general structure of a saturated fatty acid?

Accepted Answer

$$\mathrm{CH_3$(CH_2$)_nCOOH}$$

Question 12

Which of the following best describes the role of cholesterol in eukaryotic cell membranes?

Accepted Answer

Cholesterol modulates membrane fluidity and permeability, and thickens the plasma membrane.

Question 13

Which of the following is a correct statement about the melting point of fatty acids?

Accepted Answer

Melting point decreases as the number of double bonds increases.

Question 14

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

Accepted Answer

A sterol consists of four fused rings, a polar hydroxyl group, and a nonpolar alkyl side chain.

Question 15

Which of the following best explains the difference between cis and trans fatty acids in terms of their physical properties?

Accepted Answer

Trans fatty acids pack more tightly and have higher melting points than cis fatty acids.

Question 16

Which of the following is a function of vitamin K in the body?

Accepted Answer

It is a cofactor for enzymes involved in blood clot formation.

Question 17

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

Accepted Answer

They contain both hydrophilic head groups and hydrophobic tails.

Question 18

Which of the following is true regarding the blood group antigens found on glycosphingolipids?

Accepted Answer

The blood group is determined by the type of sugar present on the head group, which is controlled by specific glycosyltransferases.

Question 19

Which of the following equations represents the structure of a triacylglycerol?

Accepted Answer

$$\mathrm{CH_2OCO-R_1$\ CHOCO-R_2$\ CH_2OCO-R_3$}$$

Chatper 10

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