Question

Ratio between 2-carbon and 3-carbon intermediate having NH${}_2$ group formed in photosynthetic oxidation cycle is

• A. 2 : 1
• B. 1 : 1
• C. 3 : 2
• D. 3 : 4.

Answer 1

The correct option is A 2 : 1

A) During photorespiration, in the peroxisome, 2 molecules of glycine are transferred to the mitochondrion where they are converted into one molecule of serine. Glycine is a two carbon structure having chemical formula ${NH}_2-{CH}_2-COOH$ and serine is a three carbon structure having chemical formula ${NH}_2-CH{(CH}_{2}OH)-COOH$. So, the ratio between glycine and serine is 2 : 1.

B) Two molecules of glycine form one molecule of serine, so the ratio is 2 : 1.

C) The ratio between the 2-carbon and 3-carbon intermediate is 2 : 1.

D) Two molecules of glycine combine to form one molecule of serine.

So the correct answer is '2 : 1'.