Correct option is A
Explanation-
Sucrose phosphate synthase (SPS) is a key enzyme in the sucrose biosynthesis pathway in plants. It catalyzes the following reaction:
UDP-glucose + Fructose-6-phosphate ⟶ Sucrose-6-phosphate + UDP
Substrates are UDP-glucose and Fructose-6-phosphate
Product (before dephosphorylation) - Sucrose-6-phosphate (which is later dephosphorylated to sucrose)
Hence, the correct description of the action of SPS is that UDP-glucose and fructose-6-phosphate are substrates.
Incorrect Options-
Option b: Says substrates are the products — incorrect.
Option c: Sucrose is not the direct product of SPS (it is formed after dephosphorylation of sucrose-6-phosphate).
Option d: Reverses the products/substrates — also incorrect.
Final Answer:
Option a – UDP-glucose and Fructose-6-phosphate are used as substrates.
