Carbohydrates Metabolism (Book Questions)

Intestinal mucosal cells are the sites where hydrolysis of disaccharides, effected by the enzymes maltase, sucrase, and lactase, occurs

Intestinal mucosal cells are the sites where hydrolysis of disaccharides, effected by the enzymes maltase, sucrase, and lactase, occurs

Area where The enzyme sucrase is active.

The small intestine is the location where pancreatic digestive enzymes convert polysaccharides to disaccharides

Where does Hydrolysis reactions converting polysaccharides to disaccharides occur.

Digestion of carbohydrates begins in the mouth, where salivary enzymes convert some polysaccharides to smaller polysaccharides through breakage of glycosidic linkages

First site where breaking of glycosidic linkages occurs.

Intestinal mucosal cells are the sites where disaccharides, through hydrolysis, are converted to the monosaccharides glucose, fructose, and galactose.

Area where The monosaccharides glucose, fructose, and galactose are produced.

c. small intestine

1. The primary site within the human body where carbohydrate digestion occurs is the
a. mouth
b. stomach
c. small intestine
d. no correct response

a. mouth

2. What is the first site within the human body where breaking of polysaccharide glycosidic bonds occurs?
a. mouth
b. stomach
c. small intestine
d. no correct response

c. has no effect on polysaccharides

3. What effect does gastric juice in the stomach have on dietary polysaccharides?
a. converts polysaccharides to disaccharides
b. converts polysaccharides to monosaccharides
c. has no effect on polysaccharides
d. no correct response

b. intestinal mucosal cells

4. The enzymes that convert disaccharides to monosaccharides are associated with

a. intestinal villi
b. intestinal mucosal cells
c. the pancreas
d. no correct response

a. ATP

5. Which of the following substances is needed for monosaccharides to enter the bloodstream?
a. ATP
b. a-amylase
c. sucrase
d. no correct response

C6 molecule that carries one phosphate group, attached to carbon 6.

Specify the number of carbon atoms present and the number of phosphate groups present in each of the following glycolysis intermediates:

a. Glucose 6-phosphate

C6 molecule that carries two phosphate groups, one attached to carbon 1 and the other attached to carbon 6.

Specify the number of carbon atoms present and the number of phosphate groups present in each of the following glycolysis intermediates:

b. Fructose 1,6-bisphosphate

C3 molecule with one phosphate group, attached to carbon 3.

Specify the number of carbon atoms present and the number of phosphate groups present in each of the following glycolysis intermediates:

c. Glyceraldehyde 3-phosphate

C3 molecule. It has one phosphate group, attached to carbon 3.

Specify the number of carbon atoms present and the number of phosphate groups present in each of the following glycolysis intermediates:

d. 3-Phosphoglycerate

Phosphofructokinase

A kinase is an enzyme that is involved with phosphate group transfer. The phosphofructo portion of the enzyme name refers to a fructose phosphate. Transfer of a phosphate group to a fructose phosphate occurs in Step 3. Fructose 6-phosphate is converted to fructose 1,6-bisphosphate.

b. Phosphoglyceromutase

b. A mutase is an enzyme that shifts the position of a functional group within a molecule. Such a functional group shift occurs in Step 8, where 3-phosphoglycerate is isomerized to 2-phosphoglycerate. The phosphoglycerol portion of the enzyme name indicates that a glycerate phosphate is the substrate for the enzyme.

c. Triosephosphate isomerase

c. A triosephosphate isomerase effects the isomerization of a triose. Such a process occurs in Step 5, where dihydroxyacetone phosphate (a ketone) is converted to glyceraldehyde 3-phosphate (an aldehyde). Ketones and aldehydes with the same number of carbon atoms are often isomers.

d. Enolase

d. The only enol species in glycolysis is the compound phosphoenolpyruvate produced in Step 9 through a dehydration reaction that introduces a carbon–carbon double bond in the molecule. An enolase effects such a change.

c. Molecular O2 is not needed for the process to occur.

1. Which of the following statements concerning glycolysis is correct?

a. The pathway for the process is a cyclic pathway.
b. It occurs in the mitochondrial matrix.
c. Molecular O2 is not needed for the process to occur.
d. no correct response

a. two C3 molecules

2. The overall process of glycolysis converts a C6 molecule into

a. two C3 molecules
b. three C2 molecules
c. a different C6 molecule
d. no correct response

b. 4 and 6

3. What are the total number of steps in the C6 and C3 stages of glycolysis, respectively?

a. 5 and 5
b. 4 and 6
c. 3 and 7
d. no correct response

c. glucose 6-phosphate and fructose 6-phosphate

4. The first two intermediates in the process of glycolysis are, respectively

a. glucose 6-phosphate and glucose 1-phosphate
b. glucose 1-phosphate and fructose 6-phosphate
c. glucose 6-phosphate and fructose 6-phosphate
d. no correct response

a. three-carbon keto acid

5. Pyruvate, the end product of glycolysis, is a

a. three-carbon keto acid
b. three-carbon hydroxy acid
c. two-carbon keto acid
d. no correct response

b. net gain of two ATP

6. When one glucose molecule is processed through the glycolysis pathway, relative to ATP production/consumption, there is a

a. net loss of two ATP
b. net gain of two ATP
c. net gain of four ATP
d. no correct response

b. Steps 1 and 3

7. In what two steps of glycolysis is ATP converted to ADP?

a. Steps 1 and 2
b. Steps 1 and 3
c. Steps 7 and 10
d. no correct response

c. acetyl CoA and lactate

1. In the human body, under oxygen-rich and oxygen-poor conditions, respectively,

pyruvate is converted to

a. lactate and ethanol

b. lactate and acetyl CoA

c. acetyl CoA and lactate

d. no correct response

b. pyruvate to acetyl CoA

2. In which of the following conversions is CO2 produced?

a. lactate to pyruvate

b. pyruvate to acetyl CoA

c. pyruvate to lactate

d. no correct response

c. NAD+

3. The major purpose of lactate fermentation is the production of

a. acetyl CoA

b. O2

c. NAD+

d. no correct response

a. lactate fermentation

4. Which of the following processes involves the conversion of a C3 molecule to another

C3 molecule?

a. lactate fermentation

b. ethanol fermentation

c. pyruvate oxidation to acetyl CoA

d. no correct response

b. lactate

5. Accumulation of which of the following substances in muscle cells is the cause of

stiffness and soreness after vigorous exercise?

a. pyruvate

b. lactate

c. acetyl CoA

d. no correct response

c. electron transport chain

1. For the complete oxidation of a glucose molecule, the majority of the ATP produced

comes from which of the following phases in the oxidation process?

a. glycolysis

b. citric acid cycle

c. electron transport chain

d. no correct response

c. 30 ATP

2. The net yield of ATP for the complete oxidation of one molecule of glucose is

a. 12 ATP

b. 24 ATP

c. 30 ATP

d. no correct response

d. no correct response

3. The net yield of ATP per glucose molecule in the process of glycolysis is

a. 12 ATP

b. 14 ATP

c. 18 ATP

d. no correct response

b. glycogenesis

1. The process by which glucose is converted to glycogen is called

a. glycolysis

b. glycogenesis

c. glycogenolysis

d. no correct response

c. both glycogenesis and glycogenolysis

2. The intermediate glucose 1-phosphate is encountered in

a. glycogenesis but not glycogenolysis

b. glycogenolysis but not glycogenesis

c. both glycogenesis and glycogenolysis

d. no correct response

a. requires the investment of the equivalent of 2 ATP molecules

3. Adding a glucose unit to a growing glycogen chain

a. requires the investment of the equivalent of 2 ATP molecules

b. results in the production of 1 ATP molecule

c. does not involve triphosphate molecules

d. no correct response