Question

The first stable product in CAM/C4 plants is

• A. Starch
• B. Oxaloacetic acid
• C. Sugar
• D. Malic acid.

Answer 1

The correct option is (B):

Explanation of the correct option:

1. ​C4 plants and CAM plants follow the Hatch-Slack pathway and the crassulacean acid metabolism pathway, respectively.
2. The first stable compound formed during these pathways is oxaloacetate.
3. This compound is formed by the addition of carbon dioxide to phosphoenolpyruvate (PEP) in the presence of the enzyme phosphoenolpyruvate carboxylase.​

Explanation of the incorrect options:

Option (A):

1. ​Starch is the form of carbohydrate in which the sugar is stored in the plants.
   
2. Formation of starch occurs after photosynthesis is completed.
   

Option (C):

1. ​Sugar is the product produced at the end of photosynthesis.
   

Option (D):

1. ​Malic acid is produced from oxaloacetic acid in the C4 cycle.
   

Final Answer: The first stable product in CAM/C4 plants is oxaloacetic acid.