Question

Assertion
In mature cells, hexose monophosphate shunt replaces glycolysis.
Reason Glycolysis is a slow process which cannot feed mitochondria with raw material
(a) Both assertion and reasons are correct and the reason is the correct explanation for the assertion
(b) Both assertion and reason are correct but the reason is not the correct explanation for the assertion.
(c) The assertion is correct but the reason is incorrect
(d) Both assertion and reason are incorrect

Answer 1

Hint: HMP shunt is the alternative pathway to glycolysis and the TCA cycle for the oxidation of glucose. HMP shunt is more anabolic in nature. The liver and RBC metabolize about 30 percent of glucose by this pathway.

Complete answer:
The tissues such as liver, adipose tissue, adrenal gland, erythrocytes, tests, and lactating mammary glands are highly active in HMP shunt. Most of the tissues are involved in the biosynthesis of fatty acids and steroids which are dependent on the supply of NADPH. This is a more beneficial pathway for cells than glycolysis as no ATP is directly utilized or produced in HMP shunt. The HMP shunt is a multifunctional pathway, several interconvertible substances produced, which are proceeding in a different direction in the metabolic reaction. The NADPH produced by the HMP shunt is required by the RBC to keep the glutathione in the reduced state.
The HMP shunt is concerned with the biosynthesis of NADPH and pentose.
Importance of NADPH produced from the HMP shunt:
- Free radical scavenging
- Erythrocyte membrane integrity
-prevention of Met- hemoglobinemia
- Detoxification of drugs
- For the transparency of the eye lens.
- Macrophage bactericidal activity
So, the correct answer is, ‘both assertion and reasons are correct and the reason is the correct explanation for the assertion.’

Note:
- Cells do not use the HMP shunt pathway for energy production as ATP is neither utilized nor produced by the HMP shunt.
- NADPH is a strong inhibitor of glucose 6-phosphate dehydrogenase whereas NADPH is used in the various pathways, inhibition is relieved and the enzyme is accelerated to produce more NADPH.
- The entry of glucose 6-phosphate into the HMP pathway is controlled by the cellular concentration of NADPH.
- The synthesis of glucose 6-phosphate dehydrogenase is induced by the increased insulin/glucagon ratio after a high carbohydrate diet.