Water vapour comes out from the plant leaf through the stomatal opening. Through the same stomatal opening carbon dioxide diffuses into the plant during photosynthesis. Reason out the above statements using the following options.
(a) Both processes cannot happen simultaneously.
(b) Both processes can happen together because the diffusion coefficient of `CO_(2)`and water is different.
(c) The above processes happen only during night time.
(d) One process occurs during day time, and the other at night.

Options

A. Both processes cannot happen simultaneously.
B. Both processes can happen together because the diffusion coefficient of water of `CO_(2)` is different.
C. The above processes happen only during night time.
D. One process occurs durign day time, and the other at night.

Answer

To reason out the statements regarding the simultaneous processes of water vapor exiting and carbon dioxide entering through the stomatal openings of plant leaves during photosynthesis, we can analyze the options provided:

1. **Understanding Stomata**: Stomata are small openings on the leaf surface that allow for gas exchange. They are surrounded by guard cells that regulate their opening and closing. During the day, stomata typically open to allow carbon dioxide (CO₂) to enter for photosynthesis while also permitting water vapor (H₂O) to exit in a process called transpiration.

2. **Analyzing the Options**:
- **Option (a)**: "Both processes cannot happen simultaneously." This is incorrect because both transpiration and photosynthesis can occur at the same time, especially during daylight when stomata are open.

- **Option (b)**: "Both processes can happen together because the diffusion coefficient of CO₂ and water is different." This is the correct option. The diffusion coefficients of CO₂ and water vapor differ, allowing both gases to diffuse simultaneously through the stomata. Water vapor, being a smaller molecule, diffuses more rapidly than CO₂.

- **Option (c)**: "The above processes happen only during nighttime." This is incorrect. Photosynthesis primarily occurs during the day when sunlight is available, while transpiration can occur day and night, though it is more pronounced during the day.

- **Option (d)**: "One process occurs during daytime, and the other at night." This is also incorrect as both processes can occur during the day.

3. **Conclusion**: The correct reasoning is that both processes can happen together due to the differences in the diffusion coefficients of CO₂ and water vapor, allowing for simultaneous gas exchange through the stomata.

**Final Answer**: (b) Both processes can happen together because the diffusion coefficient of CO₂ and water is different.

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