1. Which of the following is NOT a class of lipids discussed in this module?
A) Fatty acids
B) Triacylglycerol
C) Phospholipids
D) Cholesterol
E) All of the above are discussed in this module
Answer: A) Fatty acids. Explanation: The previous module focused on the synthesis of fatty acids, while
this module focuses on the synthesis of three classes of lipids: triacylglycerol, phospholipids, and
cholesterol.
2. What is the precursor of both storage lipids and many membrane lipids?
A) Cholesterol
B) Triacylglycerol
C) Phosphatidate
D) AcetylCoA
E) None of the above
Answer: C) Phosphatidate. Explanation: Phosphatidate is a precursor of both storage lipids and many
membrane lipids.
3. How is cholesterol synthesized from acetylCoA?
A) Through a series of reactions involving enzymes and intermediates
B) Through a single-step reaction
C) Through a process of diffusion
D) Through a process of osmosis
E) None of the above
Answer: A) Through a series of reactions involving enzymes and intermediates. Explanation:
Cholesterol is synthesized from acetylCoA through a series of reactions involving enzymes and
intermediates.
4. How is cholesterol synthesis regulated?
A) By the availability of acetylCoA
B) By the activity of the enzymes involved in cholesterol synthesis
,C) By the concentration of cholesterol in the body
D) By the concentration of triacylglycerol in the body
E) Both A and B
Answer: E) Both A and B. Explanation: Cholesterol synthesis is regulated by the availability of
acetylCoA and the activity of the enzymes involved in cholesterol synthesis.
5. What is the contribution of cholesterol to the synthesis of steroid hormones?
A) Cholesterol is a precursor to steroid hormones
B) Cholesterol is a byproduct of steroid hormone synthesis
C) Cholesterol has no contribution to the synthesis of steroid hormones
D) Cholesterol inhibits the synthesis of steroid hormones
E) None of the above
Answer: A) Cholesterol is a precursor to steroid hormones. Explanation: Cholesterol is not only an
important component of membranes but also a precursor to steroid hormones.
1. Which of the following is true about phosphatidate?
a) It is a precursor of steroid hormones
b) It is synthesized from acetylCoA in four stages
c) It is a precursor of storage lipids and many membrane lipids
d) It is transported by lipoproteins throughout the body
e) It is tightly regulated at several levels
Answer: c) It is a precursor of storage lipids and many membrane lipids.
Explanation: Phosphatidate is a precursor of both storage lipids and many membrane lipids.
2. What is the common precursor for both triacylglycerol and phospholipids?
a) AcetylCoA
b) Cholesterol
c) Glycerol-3-P
d) Phosphatidate
e) Dihydroxyacetonephosphate
,Answer: c) Glycerol-3-P
Explanation: Glycerol-3-P is a common precursor for both triacylglycerol and phospholipids.
3. Which of the following is true about the structure of triacylglycerol and phospholipids?
a) They have very different structures
b) They both have a phosphate group linked to a glycerol backbone
c) They both have three fatty acids linked to a glycerol backbone
d) They both have two fatty acids linked to carbons 1 and 2 of glycerol, and a phosphate group linked to
carbon 3
e) They both have a cholesterol molecule linked to a glycerol backbone
Answer: c) They both have three fatty acids linked to a glycerol backbone
Explanation: Triacylglycerol and phospholipids have very similar structures, with both having a glycerol
backbone to which several fatty acids are linked. In the case of triacylglycerol, three fatty acids are
linked to each of the three carbon atoms of glycerol.
4. Where does significant triacylglycerol synthesis occur?
a) In all cells
b) Only in the liver and adipose tissue
c) Only in the liver
d) Only in adipose tissue
e) In the liver and other tissues
Answer: b) Only in the liver and adipose tissue
Explanation: Significant triacylglycerol synthesis only occurs in the liver and adipose tissue, whereas
phospholipid synthesis occurs in all cells since they are major components of membranes.
5. What is the function of lipoproteins in the body?
a) To transport cholesterol and triacylglycerol throughout the body
b) To synthesize cholesterol from acetylCoA
c) To regulate cholesterol synthesis at several levels
d) To act as precursors for steroid hormones
e) To transport phosphatidate throughout the body
, Answer: a) To transport cholesterol and triacylglycerol throughout the body
Explanation: Lipoproteins transport cholesterol and triacylglycerol throughout the body.
1. Where does synthesis of phospholipids occur?
a) Only in the liver
b) Only in adipose tissue
c) In all cells
d) In muscle cells only
e) In nerve cells only
Answer: c) In all cells
Explanation: Phospholipids are a major component of membranes and are required by all cells for their
synthesis.
2. What is the precursor for both triacylglycerol and phospholipids?
a) Glycerol-3-P
b) Fatty acid
c) Phosphatidate
d) Diacylglycerol
e) None of the above
Answer: c) Phosphatidate
Explanation: Phosphatidate is the precursor for both triacylglycerol and phospholipids.
3. Which carbon of glycerol-3-P is linked to a saturated fatty acid during phosphatide synthesis?
a) Carbon one
b) Carbon two
c) Carbon three
d) Carbon four
e) None of the above
Answer: a) Carbon one
A) Fatty acids
B) Triacylglycerol
C) Phospholipids
D) Cholesterol
E) All of the above are discussed in this module
Answer: A) Fatty acids. Explanation: The previous module focused on the synthesis of fatty acids, while
this module focuses on the synthesis of three classes of lipids: triacylglycerol, phospholipids, and
cholesterol.
2. What is the precursor of both storage lipids and many membrane lipids?
A) Cholesterol
B) Triacylglycerol
C) Phosphatidate
D) AcetylCoA
E) None of the above
Answer: C) Phosphatidate. Explanation: Phosphatidate is a precursor of both storage lipids and many
membrane lipids.
3. How is cholesterol synthesized from acetylCoA?
A) Through a series of reactions involving enzymes and intermediates
B) Through a single-step reaction
C) Through a process of diffusion
D) Through a process of osmosis
E) None of the above
Answer: A) Through a series of reactions involving enzymes and intermediates. Explanation:
Cholesterol is synthesized from acetylCoA through a series of reactions involving enzymes and
intermediates.
4. How is cholesterol synthesis regulated?
A) By the availability of acetylCoA
B) By the activity of the enzymes involved in cholesterol synthesis
,C) By the concentration of cholesterol in the body
D) By the concentration of triacylglycerol in the body
E) Both A and B
Answer: E) Both A and B. Explanation: Cholesterol synthesis is regulated by the availability of
acetylCoA and the activity of the enzymes involved in cholesterol synthesis.
5. What is the contribution of cholesterol to the synthesis of steroid hormones?
A) Cholesterol is a precursor to steroid hormones
B) Cholesterol is a byproduct of steroid hormone synthesis
C) Cholesterol has no contribution to the synthesis of steroid hormones
D) Cholesterol inhibits the synthesis of steroid hormones
E) None of the above
Answer: A) Cholesterol is a precursor to steroid hormones. Explanation: Cholesterol is not only an
important component of membranes but also a precursor to steroid hormones.
1. Which of the following is true about phosphatidate?
a) It is a precursor of steroid hormones
b) It is synthesized from acetylCoA in four stages
c) It is a precursor of storage lipids and many membrane lipids
d) It is transported by lipoproteins throughout the body
e) It is tightly regulated at several levels
Answer: c) It is a precursor of storage lipids and many membrane lipids.
Explanation: Phosphatidate is a precursor of both storage lipids and many membrane lipids.
2. What is the common precursor for both triacylglycerol and phospholipids?
a) AcetylCoA
b) Cholesterol
c) Glycerol-3-P
d) Phosphatidate
e) Dihydroxyacetonephosphate
,Answer: c) Glycerol-3-P
Explanation: Glycerol-3-P is a common precursor for both triacylglycerol and phospholipids.
3. Which of the following is true about the structure of triacylglycerol and phospholipids?
a) They have very different structures
b) They both have a phosphate group linked to a glycerol backbone
c) They both have three fatty acids linked to a glycerol backbone
d) They both have two fatty acids linked to carbons 1 and 2 of glycerol, and a phosphate group linked to
carbon 3
e) They both have a cholesterol molecule linked to a glycerol backbone
Answer: c) They both have three fatty acids linked to a glycerol backbone
Explanation: Triacylglycerol and phospholipids have very similar structures, with both having a glycerol
backbone to which several fatty acids are linked. In the case of triacylglycerol, three fatty acids are
linked to each of the three carbon atoms of glycerol.
4. Where does significant triacylglycerol synthesis occur?
a) In all cells
b) Only in the liver and adipose tissue
c) Only in the liver
d) Only in adipose tissue
e) In the liver and other tissues
Answer: b) Only in the liver and adipose tissue
Explanation: Significant triacylglycerol synthesis only occurs in the liver and adipose tissue, whereas
phospholipid synthesis occurs in all cells since they are major components of membranes.
5. What is the function of lipoproteins in the body?
a) To transport cholesterol and triacylglycerol throughout the body
b) To synthesize cholesterol from acetylCoA
c) To regulate cholesterol synthesis at several levels
d) To act as precursors for steroid hormones
e) To transport phosphatidate throughout the body
, Answer: a) To transport cholesterol and triacylglycerol throughout the body
Explanation: Lipoproteins transport cholesterol and triacylglycerol throughout the body.
1. Where does synthesis of phospholipids occur?
a) Only in the liver
b) Only in adipose tissue
c) In all cells
d) In muscle cells only
e) In nerve cells only
Answer: c) In all cells
Explanation: Phospholipids are a major component of membranes and are required by all cells for their
synthesis.
2. What is the precursor for both triacylglycerol and phospholipids?
a) Glycerol-3-P
b) Fatty acid
c) Phosphatidate
d) Diacylglycerol
e) None of the above
Answer: c) Phosphatidate
Explanation: Phosphatidate is the precursor for both triacylglycerol and phospholipids.
3. Which carbon of glycerol-3-P is linked to a saturated fatty acid during phosphatide synthesis?
a) Carbon one
b) Carbon two
c) Carbon three
d) Carbon four
e) None of the above
Answer: a) Carbon one
