Question

What is $C_2$ Cycle?

• A. Glycolate cycle
• B. Calvin cycle
• C. Krebs cycle
• D. TCA cycle

Answer 1

The correct option is A Glycolate cycle

Photorespiration is the wasteful process, which results in loss of carbon dioxide fixed by plants. It occurs due to oxygenase activity of RuBisCo enzyme found in $C_3$ plants. This process occurs in chloroplast, peroxisomes and mitochondria. It is also called as $C_2$ cycle, because the first stable product (phosphoglycolic acid) is a two carbon compound. Calvin cycle is called $C_3$ cycle, because the first stable product (phosphoglyceric acid) is a three carbon compound. Krebs cycle and TCA cycle are synonyms. Krebs cycle is called as TCA cycle, because the first stable product (citric acid) is having three carboxylic groups. Hence, the name tricarboxylic acid cycle.

Thus, the correct answer is option A.