Question

Describe photorespiration and how it disrupts the calvin cycle

Answer 1

Photorespiration is the process of oxygenation of RuBP and release of CO2 by the photosynthetic organs of a plant.
OR
Photorespiration is the process of light-dependent uptake of molecular oxygen (O2) concomitant with release of carbon dioxide (CO2) from organic compounds.

Phosphoglycolate formed by oxygen fixation is recycled to the Calvin cycle intermediate phosphoglycerate in the photorespiratory pathway. This reaction cascade consumes energy and reducing equivalents and part of the afore fixed carbon is again released as CO2. Because of this, photorespiration was often viewed as a wasteful process. 

Answer 2

Dear Student,

◆ Photorespiration disrupts Calvin cycle by -

• In photorespiration, RuBisCO enzyme takes up oxygen and carbon dioxide is liberated in air.
• It is said to be wasteful reaction As carbon dioxide (which is required for photosynthesis) is wasted here.
• Usually Calvin cycle results in gain of 6 fixed C-atoms.
• Photorespiration is associate with loss of 3 C-atoms which competes Calvin cycle.
• Hence, Photorespiration disrupts Calvin cycle by loss of fixed C-atoms.

Thanks dear. Hope this helps you...