Chapter 16 Self-test questions

. Which of the following statements about gluconeogenesis is correct?

Muscles have a large glycogen store which gives rise to blood glucose during prolonged starvation.

Fatty acids are plentiful in the blood during starvation and are used for glucose synthesis.

The enzyme glucose-6-phosphatase hydrolyses glucose-6-phosphate and is present in most cells.

Gluconeogenesis enables the liver to maintain blood glucose levels during starvation.

. Which of the following statements about the use and synthesis of glucose in the body is correct?

Brain can use fatty acids for all its energy needs.

Red blood cells can use fatty acids for all their energy needs.

The brain can use ketone bodies for all its energy needs.

The brain can use glucose for all its energy needs.

. Which of the following statements about the process of gluconeogenesis is correct?

In gluconeogenesis pyruvate is first converted to phosphoenolpyruvate by phosphoenolpyruvate carboxykinase.

In gluconeogenesis fructose-1:6-bisphosphatase converts fructose-1,6-bisphosphate into fructose-1-phosphate.

Glucose-6-phosphatase hydrolyses glucose-6-phosphate to release glucose into the blood.

Glucose-6-phosphatase hydrolyses glucose-6-phosphate and is found in liver and muscle.

. Which of the following statements about the sources of pyruvate used by the liver for gluconeogenesis is correct?

The main source of glucose carbons for gluconeogenesis is pyruvate synthesised from acetyl-CoA.

The main source of glucose carbons cannot occur from muscles as they do not undergo gluconeogenesis.

The main source of glucose carbons in gluconeogenesis is pyruvate released from muscles.

The main source of glucose carbons for gluconeogenesis is alanine derived from breakdown of muscle proteins.

. Which of the following statements about the effect of ethanol metabolism on gluconeogenesis is correct?

The metabolism of ethanol by the liver decreases the NADH/NAD⁺ ratio reducing its ability to perform gluconeogenesis.

The reduction of ethanol by the liver increases the NADH/NAD⁺ ratio reducing its ability to perform gluconeogenesis.

The oxidation of ethanol by the liver increases the NADH/NAD⁺ ratio increasing its ability to perform gluconeogenesis.

The metabolism of ethanol by the liver increases the NADH/NAD⁺ ratio reducing its ability to perform gluconeogenesis.

. What is achieved by the 'Cori cycle' which involves metabolism of lactate?

Lactate is taken up by the liver for synthesis of glucose.

Metabolic alkalosis is prevented by removing lactate from the blood.

Lactate is removed from the blood as it inhibits glycolysis in the erythrocyte.

Lactate is used by the muscle for fuel.

. What happens to the glycerol part of triacylglycerols when they are hydrolysed in the capillaries of adipose tissue?

Glycerol enters the adipocyte and is phosphorylated so that re-esterification of the released fatty acids can take place inside the cell.

Glycerol is transported to the liver where it can enter the glycolytic or gluconeogenic pathway.

Glycerol is transported to the kidney where it can be used as a buffer for H+ released in metabolism.

Glycerol is transported to the muscle to be used as fuel.

. Which of the following statements about gluconeogenesis is not correct?

Lactate from muscle vigorous muscle activity can be used as a carbon source in gluconeogenesis.

Glycerol from the hydrolysis of triacylglycerols is converted to glucose in gluconeogenesis.

Lactate from red blood cells can be used as a carbon source in gluconeogenesis.

Fatty acids from the hydrolysis of triacylglycerols can be used as a carbon source in gluconeogenesis.

. Why is it possible to produce glucose from lactate but not from fatty acids?

Because the conversion of pyruvate into acetyl CoA is irreversible.

Because the structure of lactate resembles that of glucose.

Because the erythrocyte produces lactate but can only use glucose as fuel.

Because fatty acid oxidation takes place in muscle and gluconeogenesis takes place in the liver.

. What is the fate of lactate produced by vigorously exercising muscle and by erythrocytes?

It is excreted by the kidney.

It is used to synthesise fatty acids.

It can be oxidised by the kidney.

It goes to the liver and is converted into glucose.

. Why do some genetic groups suffer unpleasant effects such as tachycardia and vasodilation when they consume even moderate amounts of alcohol?

Because they lack alcohol dehydrogenase.

Because they cannot metabolise acetaldehyde.

Because they have excessive amounts of aldehyde dehydrogenase.

Because they have a deficiency of cytochrome P450 which is involved in detoxification reactions.

. In fasting, amino acids from muscle protein breakdown travel to the liver for gluconeogenesis. Which amino acids are found in the bloodstream in the highest concentrations in such circumstances?

Alanine and tyrosine.

Valine and lysine.

Glycine and glutamate.

Alanine and glutamine.

Chapter 16 Self-test questions

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