Question

In plants that undergo photorespiration, the atmospheric $CO_2$ is fixed via the
A) Glycolate cycle.
B) Krebs cycle
C) Calvin cycle
D) None of the above

Answer 1

Photorespiration refers to the plant metabolism where the enzyme RuBisCO oxygenates. Photorespiration is a wasteful pathway that competes with the Calvin cycle and it begins with RuBisCO.

Complete answer
Option A) Glycolate cycle: Glycolate cycle is a complex metabolic pathway. The production of amino acids serine and glycine from non-phosphorylated intermediates of photosynthesis is thought to be the primary mechanism of the Glycolate cycle.
Option B) Krebs cycle: Krebs cycle is also known as tricarboxylic acid cycle. The Krebs cycle is part of the larger glucose metabolism. Krebs cycle is the second stage of cellular respiration. During the process of Krebs cycle.
Option C) Calvin cycle: Calvin cycle is the process that plants and algae turn carbon dioxide into sugar. Calvin cycle reaction can be divided into three main stages. The main product of the Calvin cycle is $6PGAL$ molecules. In plants that undergo photorespiration, the atmospheric $CO_2$ is fixed via the Calvin cycle.
Option D) None of the above: This option is wrong because in above options Calvin cycle is the correct answer.

Hence the correct answer is option C.

Note:
$C3$ plants are called photo respiring plants. In these types of plants atmospheric carbon dioxide is fixed into sugars during the dark reaction using the Calvin cycle. This is the process by which the plants and algae use to turn carbon dioxide into sugar from air. In plants that undergo photorespiration, the atmospheric $CO_2$ is fixed via the Calvin cycle.