Chapter 15 Self-test questions

. Which of the following statements about the role of the pentose phosphate pathway is correct?

The pentose phosphate pathway produces ribose-5-phosphate and NADPH.

The pentose phosphate pathway oxidises glucose-6-phosphate completely to carbon dioxide and water.

The rate-limiting reaction of the pentose phosphate pathway is catalyzed by transketolase.

The pentose phosphate pathway occurs in the mitochondria of most cells.

. Which of the following statements about the oxidative section of the pentose phosphate pathway is correct?

The pentose phosphate pathway generates NADH.

The pentose phosphate pathway oxidizes NADPH to NADP⁺.

The rate-limiting reaction of the pentose phosphate pathway is catalyzed by glucose-6-phosphatase.

The pathway supplies ribose-5-phosphate and NADPH in the quantities the cells require.

. Which of the following statements about the nonoxidative section of the pentose phosphate pathway is correct?

The nonoxidative reactions of the pentose phosphate pathway are not reversible.

Transketolase is an enzyme that transfers three-carbon units in the pentose phosphate pathway.

Transaldolase is an enzyme that transfers two-carbon units in the pentose phosphate pathway.

Pentoses undergo isomerizations in the pentose phosphate pathway.

. Which of the following statements about the use of the NADPH generated from the pentose phosphate pathway is not true?

NADPH generated from the pentose phosphate pathway is used for steroid synthesis.

NADPH generated from the pentose phosphate pathway is used for the regeneration of glutathione to its reduced state.

NADPH generated from the pentose phosphate pathway is used for the synthesis of fatty acids.

NADPH generated from the pentose phosphate pathway and cytoplasmic NADH is metabolically interchangeable.

. Which of the following statements about the pentose phosphate pathway is not true?

The pentose phosphate pathway relies on the availability of NADP⁺.

The pentose phosphate pathway has an irreversible oxidative section and a reversible non oxidative section.

The pentose phosphate pathway enables excess ribose to be metabolised.

The pentose phosphate pathway relies on the availability of NADPH.

. Haemolytic anaemia can be triggered in people deficient in glucose-6- phosphatase by infection. What is the mechanism?

Infection leads to increased production of immunoglobulins which attack the erythrocyte.

Infection is accompanied by generation of oxidants which destroy the erythrocyte membrane.

Infection leads to weakening of erythrocyte cell membranes by the attachment of bacterial toxins.

Infection compromises the immune system which is unable to protect the erythrocyte.

. What is an important function of the pentose phosphate pathway?

Generation of NADH for the production of ATP by the electron transport chain.

Generation of NADPH for fatty acid synthesis.

Generation of NAD which is necessary for glycolysis.

Generation of NADP needed in amino acid metabolism.

. Which of the following statements about the use of the pentose phosphate pathway in red blood cells is correct?

Mature red blood cells do not need the pentose phosphate pathway since they do not divide.

Mature red blood cells do not need the pentose phosphate pathway since they do not synthesize fat.

Mature red blood cells need the pentose phosphate pathway to oxidize the glucose-6-phosphate.

Mature red blood cells need the pentose phosphate pathway for the production of NADPH.

. Which of the following statements about the nonoxidative section of the pentose phosphate pathway are correct? Please select all that apply.

Glycolysis provides intermediates for the pentose phosphate pathway.

The pentose phosphate pathway provides intermediates for glycolysis.

The pentose phosphate pathway cannot provide pentoses in the quantities the cell requires.

There is a relationship between glycolysis and the pentose phosphate pathway in the liver.

There is no relationship between glycolysis and the pentose phosphate pathway in the liver.

. Which of the following tissues/organs have an active pentose phosphate pathway directed to the generation of NADPH but not so important for ribose phosphate production?

Liver.

Erythrocyte.

Muscle.

Adipocyte.

. Glucose-6-phosphate dehydrogenase deficiency leads to which one of the following conditions?

Microcytic anaemia.

Macrocytic anaemia.

Haemocytopenia.

Haemolytic anaemia.

. Why is glutathione important in the erythrocyte?

It maintains the iron in haem in the ferrous form.

It maintains the iron in haem in the ferric form.

It maintains the concentration of methaemoglobin.

It produces hydrogen peroxide.

Chapter 15 Self-test questions

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