Question

PGA as the first CO₂ fixation product was discovered in the photosynthesis of:

• A. Alga
• B. Angiosperm
• C. Gymnosperm
• D. Bryophyte

Answer 1

The correct option is A

Alga

The correct option is A.

Explanation of the correct answer:

1. 3-phosphoglyceric acid (PGA) is a 3-carbon acid that is the first product of carbon fixation in C3 plants.
2. It was discovered by Malvin Calvin while studying dark reactions.
3. He discovered it by using radioactive ¹⁴C in algal photosynthesis.

Explanation of the incorrect options:

Option B:

1. PGA as the first stable product of carbon fixation in C3 plants was discovered in the photosynthesis of alga.
2. Angiosperms are C4 plants.
3. Hence this option is incorrect.

Option C:

1. PGA as the first stable product of carbon fixation in C3 plants was discovered in the photosynthesis of alga.
2. Gymnosperms are C4 plants.
3. Hence this option is incorrect.

Option D:

1. PGA as the first stable product of carbon fixation in C3 plants was discovered in the photosynthesis of alga.
2. Bryophytes are C4 plants.
3. Hence this option is incorrect.

Final answer: PGA as the first CO₂ fixation product was discovered in the photosynthesis of alga.