Question

A plant in your garden avoids photorespiratory losses, has improved water use efficiency, shows high rates of photosynthesis at high temperatures and has improved efficiency of nitrogen utilization. In which of the following physiological groups would you assign this plant?

• A. C₄
• B. CAM
• C. Nitrogen fixer
• D. C₃

Answer 1

The correct option is A

C₄

The correct option is A.

Explanation of correct option:

1. Plants that grow in tropical dry areas undergo the C₄ pathway. Example: maize, sorghum.
2. In C₄ plants, the first product of CO₂ fixation is oxaloacetic acid (a four-carbon acid).
3. C₄ plants possess a distinct type of leaf anatomy called ‘Kranz’ anatomy in which the mesophyll cells form a cluster around the bundle-sheath.
4. C₄ plants show a high photosynthesis rate at high temperatures, efficiently utilize nitrogen and water, lack photorespiration, etc.

Explanation of incorrect option:

Option B:

1. Among C₄ and CAM plants, C₄ shows a higher photosynthesis rate at high temperatures.
2. CAM plants fix CO₂ during the night when the temperature is lower.

Option C:

1. Rhizobium is a type of bacteria that lives in the roots of certain plants (legumes). They help in fixing atmospheric nitrogen.
2. Such type of plants doesn’t show a high photosynthetic rate at high temperature. They are also unable to avoid photorespiration.

Option D:

1. In C₃ plants, the first product of CO₂ fixation is 3-phosphoglyceric acid (a four-carbon acid).
2. C₃ plants show photorespiration.

Final answer: A plant in your garden avoids photorespiratory losses, has improved water use efficiency, shows high rates of photosynthesis at high temperatures, and has improved the efficiency of nitrogen utilization. This plant belongs to the C4 group.