Which one of the following is wrong in relation to photorespiration:
- It occurs in chloroplasts
- It occurs in daytime only
It is a characteristic of C4 plants
It is a characteristic of C3 plants
The Correct Option is C
Solution and Explanation
Photorespiration is primarily a characteristic of C3 plants, not C4 plants. C3 and C4 plants have different carbon fixation pathways. Photorespiration occurs more prominently in C3 plants due to the oxygenase activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), which leads to the wasteful breakdown of carbon compounds in the presence of oxygen. C4 plants have evolved mechanisms to minimize photorespiration, making it less common in these plants.
So, the correct option is (C): It is a characteristic of C4 plants
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Concepts Used:
Photorespiration
Photorespiration is a wasteful process in plants in which plants intake oxygen, and sunlight and release carbon dioxide and no glucose is formed. Photorespiration generally takes place when the concentration of oxygen in the leaves is very high and that of carbon dioxide is very low.
In Calvin cycle carbon dioxide fixation does not take place . Hence, instead of carbon dioxide oxygen reacts with RuBP.
Photorespiration in C3 and C4 Plants:
- C4 plants do not undergo photorespiration due to their special mechanism to increase the CO2 level for enzyme binding.
- In Hatch and Slack Pathway, C4 acid and oxaloacetic acid breaks down to release CO2.
- This ensures a high concentration of intercellular CO2.
- Thus, in C4 plants, RuBisCO is more active as a carboxylase enzyme rather than as an oxygenase.
- This is why C4 plants have better productivity.