Which statement best explains what happens to a leaf when it has lost much-needed water?

• A. The leaf absorbs more carbon dioxide to compensate for water loss.
• B. The leaf wilts because loss of water reduces turgor pressure in its cells.
• C. The leaf becomes greener as chlorophyll production increases.
• D. The leaf's stomata open wider to increase transpiration.

Answer: (B)

Verified step by step guidance

1. Understand the concept of turgor pressure: Turgor pressure is the pressure exerted by water inside the plant cell against the cell wall. It is essential for maintaining the rigidity and structure of plant cells, especially in leaves.
2. Recognize the role of water in maintaining turgor pressure: When a leaf loses water, the turgor pressure in its cells decreases. This loss of pressure causes the cells to become flaccid, leading to wilting of the leaf.
3. Eliminate incorrect options: Analyze each statement provided in the problem. For example, absorbing more carbon dioxide does not directly compensate for water loss, and stomata opening wider would increase water loss through transpiration, worsening the situation.
4. Focus on the correct explanation: The correct answer is that the leaf wilts because loss of water reduces turgor pressure in its cells. This is a direct physiological response to water loss.
5. Relate this concept to plant survival: Explain that plants have mechanisms to minimize water loss, such as closing stomata during drought conditions, to prevent excessive wilting and maintain their structure.