Question

Consider the following statement regarding starch and sucrose synthesis during day time and select the correct ones.
(i) Triose phosphate is confined to chloroplast and is utilized for the synthesis of starch only.
(ii) Triose phosphate is trans located to cytosol from chloroplast.
(iii) Triose phosphate is utilised for the synthesis of both starch and sucrose.
(iv) Triose phosphate is trans located from cytosol to chloroplast.

• A. (i) and (iii)
• B. (ii) and (iii)
• C. (ii) and (iv )
• D. (iii) and (iv)

Answer 1

The correct option is B (ii) and (iii)

Glyceraldehyde-3- phosphate (G3P) or 3-phosphoglyceraldehyde (PGAL), also known as triose phosphate, is a chemical compound that occurs as an intermediate in several central metabolic pathways of all organisms. It is an intermediate in photosynthesis. A part of triose phosphate is trans located to cytosol from chloroplast and is utilised for the synthesis of glucose,sucrose, starch, etc. The reaction may be summarised as follows:

Fructose-1, 6-bisphosphate + $H_{2}O\underset{Fructose-6-phosphate+Pi}{\overset{Phosphatase}{\to }}$

Fructors-6-phosphate is then converted into other sugars (viz,glucose, sucrose, starch, etc). depending upon plants need.

So the correct answer is '(ii) and (iii)'.