Chapter 14 Quiz

Question 1

The products of digestion provide the tissues with the building blocks for the biosynthesis of complex molecules and also with the fuel for metabolic processes.

Answer 1

True

Question 2

Nearly all products of digestion of carbohydrate, fat, and protein are metabolized to a common metabolite, acetyl-CoA, before oxidation to CO2 in the citric acid cycle.

Answer 2

True

Question 3

Acetyl-CoA is also the precursor for synthesis of long-chain fatty acids and steroids (including cholesterol) and ketone bodies.

Answer 3

True

Question 4

Glucose provides carbon skeletons for the glycerol of triacylglycerols and nonessential amino acids.

Answer 4

True

Question 5

Water-soluble products of digestion are transported directly

to the liver via the hepatic portal vein.

Answer 5

True

Question 6

The liver regulates the concentrations of glucose and amino acids available to other tissues.

Answer 6

True

Question 7

Lipids and lipid-soluble products of digestion enter the bloodstream from the lymphatic system, and the liver clears the remnants after extra-hepatic tissues have taken up fatty acids.

Answer 7

True

Question 8

Pathways are compartmentalized within the cell. Glycolysis, glycogenesis, glycogenolysis, the pentose phosphate pathway, and lipogenesis occur in the cytosol.

Answer 8

True

Question 9

The mitochondria contain the enzymes of the citric acid cycle and for β-oxidation of
fatty acids, as well as the respiratory chain and ATP synthase.

Answer 9

True

Question 10

The membranes of the endoplasmic reticulum contain the enzymes for a number of other processes, including triacylglycerol synthesis and drug metabolism.

Answer 10

True

Question 11

Metabolic pathways are regulated by rapid mechanisms affecting the activity of existing enzymes, that is, allosteric and covalent modification (often in response to hormone action) and slow mechanisms that affect the synthesis of enzymes.

Answer 11

True

Question 12

Dietary carbohydrate and amino acids in excess of requirements can be used for fatty acid and hence triacylglycerol synthesis.

Answer 12

True

Question 13

In fasting and starvation, glucose must be provided for the brain and red blood cells; in the early fasting state, this is supplied from glycogen reserves.

Answer 13

True

Question 14

In order to spare glucose, muscle and other tissues do not take up glucose when insulin secretion is low; they utilize fatty acids (and later ketone bodies) as their preferred fuel.

Answer 14

True

Question 15

Adipose tissue releases nonesterified fatty acids in the fasting state.

Answer 15

True

Question 16

In prolonged fasting and starvation these are used by the liver for synthesis of ketone bodies, which are exported to provide the major fuel for muscle.

Answer 16

True

Question 17

Most amino acids, arising from the diet or from tissue protein turnover, can be used for gluconeogenesis, as can the glycerol from triacylglycerol.

Answer 17

True

Question 18

Neither fatty acids, arising from the diet or from lipolysis
of adipose tissue triacylglycerol, nor ketone bodies, formed from fatty acids in the fasting state, can provide substrates for gluconeogenesis.

Answer 18

True