Question 1

Which of the following statements best describes the amphipathic nature of fatty acids?

Accepted Answer

Fatty acids possess both a hydrophobic hydrocarbon chain and a hydrophilic carboxyl group, making them amphipathic.

Question 2

A fatty acid is designated as 18:2(9,12). What does this notation indicate?

Accepted Answer

The fatty acid has 18 carbons and two double bonds at carbons 9 and 12 from the carboxyl end.

Question 3

Which enzyme catalyzes the rate-limiting step in de novo fatty acid synthesis, and what is the reaction it performs?

Accepted Answer

Acetyl CoA carboxylase; carboxylation of acetyl CoA to malonyl CoA

Question 4

During periods of fasting, which hormone activates hormone-sensitive lipase (HSL) in adipose tissue, and what is the consequence?

Accepted Answer

Glucagon; hydrolysis of triacylglycerol to release fatty acids and glycerol

Question 5

Which of the following best explains why long-chain fatty acids require the carnitine shuttle for mitochondrial entry?

Accepted Answer

CoA derivatives of long-chain fatty acids cannot cross the inner mitochondrial membrane, so carnitine transports the acyl group.

Question 6

A patient with medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is most likely to present with which of the following symptoms during fasting?

Accepted Answer

Hypoglycemia and hypoketonemia

Question 7

Which of the following reactions requires biotin as a coenzyme?

Accepted Answer

Carboxylation of acetyl CoA to malonyl CoA by acetyl CoA carboxylase

Question 8

Which of the following best describes the fate of glycerol released from adipose tissue during lipolysis?

Accepted Answer

It is transported to the liver, where it is converted to glycerol 3-phosphate and can be used for gluconeogenesis.

Question 9

Which of the following statements about ketone bodies is correct?

Accepted Answer

Ketone bodies are synthesized in the liver and used by peripheral tissues with mitochondria as an energy source.

Question 10

Which of the following is a consequence of uncontrolled type 1 diabetes mellitus with respect to ketone body metabolism?

Accepted Answer

Increased ketone body synthesis leading to ketoacidosis

Question 11

Which of the following is the correct sequence of events in mitochondrial β-oxidation of a saturated fatty acid?

Accepted Answer

Oxidation (FADH$$_2$$ production), hydration, oxidation (NADH production), thiolytic cleavage

Question 12

A deficiency in vitamin B$$_{12} ($$cobalamin) would most directly impair which step in odd-chain fatty acid metabolism?

Accepted Answer

Conversion of L-methylmalonyl CoA to succinyl CoA

Question 13

Which of the following best explains why the liver cannot utilize ketone bodies for energy?

Accepted Answer

The liver lacks the enzyme thiophorase required to convert acetoacetate to acetoacetyl CoA.

Question 14

Which of the following is a major source of NADPH required for fatty acid synthesis in the liver?

Accepted Answer

Pentose phosphate pathway and malic enzyme reaction

Question 15

Which of the following best describes the effect of malonyl CoA on fatty acid metabolism?

Accepted Answer

It inhibits CPT-1, preventing entry of long-chain fatty acids into mitochondria for oxidation.

Question 16

Which of the following is true regarding the structure of triacylglycerols (TAGs)?

Accepted Answer

TAGs consist of three fatty acids esterified to a glycerol backbone.

Question 17

Which of the following enzymes is responsible for the initial activation of fatty acids before β-oxidation?

Accepted Answer

Fatty acyl-CoA synthetase (thiokinase)

Question 18

Which of the following is a correct statement about the synthesis of very-long-chain fatty acids (VLCFA)?

Accepted Answer

VLCFA synthesis occurs in the smooth endoplasmic reticulum (SER) by elongation of existing fatty acids.

Question 19

Which of the following best explains the clinical significance of the accumulation of methylmalonic acid in urine?

Accepted Answer

It suggests a deficiency in vitamin B$$_{12} or a $$genetic defect in methylmalonyl CoA mutase.

Fatty Acid, Triacylglycerol, and Ketone Body Metabolism: Structure, Function, and Pathways

Study Guide - Practice Questions