Question

Once a carbon atom from carbon dioxide in the air becomes part of an organic molecule through the process of photosynthesis, which of the following paths could that carbon atom take?

Select one:

A. become part of a nucleic acid

B. become part of a water molecule

C. exit the plant in a molecule of CO₂

D. both A and C

E. both B and C

Answer 1

D. both A and C.

The carbon could become part of a nucleic acid. PRPP (phosphoribosyl pyrophosphate) is the main precursor of nucleic acid synthesis, which also requires several amino acids such as glutamine and glycine. PRPP is formed from ribose 5-phosphate, a by-product of photosynthesis pathways.

The carbon cannot be a part of water molecule since water molecule contains only hydrogen and oxygen atoms but not carbon.

Respiration occurs in plants during night time, when carbon dioxide is released.