Question

Rubisco is incredibly useful for carbon fixation. However, in the presence of too much oxygen, rubisco binds to the O2 molecules rather than CO2, causing the cell to go through photorespiration rather than photosynthesis. Why is this a bad thing, and if rubisco is so useful, why does it behave in a way that is so bad for the plant?

A. Photorespiration helps plants grow faster.
B. Rubisco prevents plants from photosynthesizing.
C. Photorespiration is an essential part of plant metabolism.
D. Photorespiration is less efficient than photosynthesis.

Answer 1

Rubisco binds to oxygen instead of carbon dioxide in the presence of high oxygen levels, leading to photorespiration. This is a problem because photorespiration is less efficient than photosynthesis and can limit plant growth and productivity. Some plants have evolved alternative pathways to minimize the effects of photorespiration.

Step-by-step explanation:

The enzyme Rubisco is essential for carbon fixation in photosynthesis. However, in the presence of too much oxygen, Rubisco binds to oxygen molecules instead of carbon dioxide, leading to photorespiration. This is a problem because photorespiration is less efficient than photosynthesis and can limit plant growth and productivity.

The reason Rubisco behaves in this way is due to the evolutionary history of plants. Rubisco is an ancient enzyme that evolved when oxygen levels were much lower than they are today. The preference for oxygen over carbon dioxide is a result of Rubisco's structure and function, and it has not been optimized for high oxygen environments.

To overcome the limitations of Rubisco and photorespiration, some plants, like C4 plants, have evolved alternative pathways for carbon fixation that minimize the effects of photorespiration. These plants concentrate carbon dioxide in specific cells, allowing them to continue photosynthesis even in the presence of high oxygen levels.