Question

In addition to the normal process of oxidation of carbohydrates through glycolysis and Krebs' cycle, there is another process by which plants could oxidise carbohydrates to obtain energy. In this process, hexose sugars undergo oxidative degradation through 5-C sugar intermediates and hence it is known as Pentose phosphate pathway(PPP). Which of the following statements is not true with regard to PPP?

• A. It is an alternative to glycolysis and also acts as a safety valve or shunt to glycolysis.
• B. It is common in plants and occurs in certain specialised tissues of animal body, e.g., liver, adipose tissue, testes, ovary, adrenal cortex, lactating mammary gland, eye lens and cornea.
• C. It occurs only in cytoplasm but not in any cell organelle.
• D. It is also called as hexose monophosphate shunt (HMP pathway).

Answer 1

Answer: (C)

It occurs only in cytoplasm but not in any cell organelle.

Pentose phosphate pathway (PPP) or hexose monophosphate shunt (HMP pathway) occurs in the cytoplasm in most organisms, however, in plants, many of its steps occur in plastids also.

So the correct option is C.