Which of the following are water-conducting cells that are dead at functional maturity?

• A. Parenchyma cells
• B. Sieve tube elements
• C. Collenchyma cells
• D. Tracheids

Answer: (D)

Verified step by step guidance

1. Begin by understanding the function of water-conducting cells in plants. These cells are part of the xylem tissue, which is responsible for transporting water and nutrients from the roots to the rest of the plant.
2. Next, identify the characteristics of tracheids. Tracheids are elongated cells in the xylem that facilitate water conduction. They are dead at functional maturity, meaning they lose their protoplasts and become hollow tubes, allowing water to pass through efficiently.
3. Compare tracheids with other cell types listed in the problem. Parenchyma cells are living cells that are involved in storage, photosynthesis, and tissue repair. Sieve tube elements are part of the phloem and are involved in transporting sugars and other organic nutrients; they are alive at maturity. Collenchyma cells provide structural support and are also alive at maturity.
4. Recognize that tracheids are unique among the options provided because they are dead at functional maturity, which is a key characteristic for efficient water conduction in the xylem.
5. Conclude that tracheids are the correct answer based on their role in water conduction and their state of being dead at functional maturity, which distinguishes them from the other cell types listed.