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Why does Photorespiration not occur in CAM Plants?

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  • Last Updated : 02 Nov, 2022
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Breath alludes to the digestion of oxygen and the arrival of carbon dioxide. In cell breath, it is a positive term, a cycle imperative to life. Yet, photorespiration is a deplorable term since it addresses an extreme misfortune to the most common way of involving light energy in photosynthetic creatures to fix carbon for resulting starch union. By promoting the deficiency of up to half of the carbon that has been fixed to the detriment of light energy, photorespiration fixes crafted by photosynthesis.

Photorespiration doesn’t happen in CAM plants on the grounds that these plants have developed a superior variation system to that end they keep away from photorespiration; they use PEP Carboxylase rather than RUBISCO for the retention of CO2 and in cam plants, carbon obsession and Calvin cycle both cycles happen at different time. Both C4 and CAM plants, at last, deliver carbon dioxide from natural intermediates to the Calvin Cycle and Rubisco however CAM plants, all around adjusted to dry conditions, open their stomata around evening time for the obsession of CO2 into natural mixtures ( lessen water lost through the stomata).

Carbon dioxide is put away as natural mixtures as the night progressed, then CO2 is delivered to the Calvin cycle in the first part of the day as the light comes up on the grounds that Calvin Cycle requires ATP and NADPH from the light-reliant responses.

However, in the first part of the day, the stomata are shut. The grouping of carbon dioxide inside the cells will be a lot higher than oxygen. Photorespiration will be decreased as carbon dioxide, not oxygen tied to Rubisco’s dynamic site. This is the primary explanation that photorespiration doesn’t happen in CAM plants. CAM plants don’t show photorespiration as they

Keep your stomata shut during the day; Use PEP carboxylase, and  Fix CO2 into natural corrosive during the evening and deliver CO2 during the day. Calvin cycle occurs around evening time.



CAM plants will be plants that fix carbon dioxide through CAM pathways. CAM implies Crassulacean Acid Metabolism. This pathway was first found quite a while in the Crassulaceae family. It is used during dry and parched conditions. The CAM pathway is adjusted by plants to diminish water misfortune and photorespiration. A portion of the CAM plants incorporates hydrilla, cactus, pineapple, and so forth.

Photorespiration does not occur in CAM plants because;

They use PEP carboxylase: The CAM plants keep away from photorespiration by isolating the light-reliant responses and the utilization of CO2 in the Calvin cycle. They fix CO2 during the night with the assistance of PEP carboxylase which is utilized during the following day. Subsequently, photorespiration doesn’t occur.

During the day

The CAM plants fix CO2 as a natural corrosive during the night however not without the assistance of PEP carboxylase. Calvin cycle around evening time: This choice is wrong since the Calvin cycle happens during the day. Just obsession with CO2 with natural acids occurs during the night. Accordingly, Using PEP carboxylase is the right response.

During night

The CAM plants open their stomata and permit CO2 to diffuse into the leaves. The diffused CO2 is fixed into oxaloacetate with the assistance of PEP carboxylase. This is again changed over into malate or one more sort of natural corrosive. The natural corrosive is put away in the vacuoles until the following day. During sunshine, the CAM plants don’t open their stomata, however, can in any case perform photosynthesis. This is on the grounds that the natural acids put away in the vacuole are separated to deliver CO2 which enters the Calvin cycle. This controlled delivery keeps a high convergence of carbon dioxide (CO2) around rubisco.


Sedum, Kalanchoe, Pineapple, Opuntia, and Snake plants are instances of CAM plants. These plants additionally perform twofold carbon dioxide obsession. The carbon dioxide acceptor in CAM plants is Phosphoenol pyruvic corrosive (PEP) during the evening and Ribulose bisphosphate is the carbon dioxide acceptor during the daytime. Some plants that are adjusted to dry conditions, like desert flora and pineapples

FAQs on Photorespiration

Question 1: List the factors which affect photorespiration.


All the factors affect the oxygenase enzyme which directly affects the photorespiration

  • O2
  • CO2
  • Temperature

Question 2: What do you mean by the Warburg effect?


Otto Warburg observed that O2 inhibits photorespiration in C3 plants and this phenomenon is known as the Warburg effect

Question 3: Where does photorespiration not happen in the plant?


These plants keep up with high centralization of carbon dioxide in the pack sheath cells and nonattendance of grana guarantees no arrival of oxygen due to photolysis. 

Question 4: Difference between C3, C4, and CAM Plants?






Kranz anatomy Absent Present Absent
Initial CO2 Receptor RuBP PEP PEP
CO2: ATP 1 : 3 1:5 1: 5
First stable Product 3-PGA Oxaloacetate Oxaloacetate
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