A botanist discovered a mutant plant that is unable to produce the material that forms the Casparian strip. This plant is __________.

• A. unable to fix nitrogen
• B. unable to transport water or solutes to the leaves
• C. able to exert greater root pressure than normal plants
• D. unable to lose water by transpiration
• E. unable to control the amounts of water and solutes it absorbs

Answer: (E)

Verified step by step guidance

1. Understand the function of the Casparian strip: The Casparian strip is a band of cell wall material found in the roots of plants, specifically in the endodermis. It is made of suberin, a waxy substance that is impermeable to water and solutes.
2. Recognize the role of the Casparian strip: It acts as a selective barrier, controlling the movement of water and solutes into the vascular system of the plant. This ensures that only certain substances can pass through, while others are blocked.
3. Consider the consequences of a missing Casparian strip: Without this barrier, the plant cannot regulate the uptake of water and solutes effectively. This means that the plant may absorb excessive amounts of water and solutes, or fail to absorb enough, leading to imbalances.
4. Relate the problem to the options given: The inability to control water and solute absorption directly affects the plant's ability to transport these substances to the leaves, exert root pressure, and manage transpiration.
5. Conclude with the correct answer: The mutant plant, lacking the Casparian strip, is unable to control the amounts of water and solutes it absorbs, which is crucial for maintaining homeostasis and proper physiological functions.