Which combination of plant structures primarily helps maintain water balance within a plant by regulating water uptake and loss?

• A. Root hairs and stomata
• B. Chloroplasts and mitochondria
• C. Cuticle and cell wall
• D. Xylem and phloem

Answer: (A)

Verified step by step guidance

1. Identify the primary function of each structure listed in the options. For example, root hairs are involved in water absorption, stomata regulate water loss through transpiration, chloroplasts and mitochondria are involved in energy processes, cuticle and cell wall provide protection and structure, and xylem and phloem are responsible for water and nutrient transport.
2. Focus on the structures directly involved in water uptake and loss. Root hairs increase the surface area for water absorption from the soil, while stomata are small openings on leaves that control water loss through transpiration and gas exchange.
3. Eliminate options that are not directly related to water balance. For instance, chloroplasts and mitochondria are involved in photosynthesis and cellular respiration, not water regulation. Similarly, the cuticle and cell wall provide structural support and protection but do not regulate water uptake or loss.
4. Consider the role of xylem and phloem. While they are essential for transporting water and nutrients throughout the plant, they do not directly regulate water uptake or loss like root hairs and stomata do.
5. Conclude that the combination of root hairs and stomata is the correct answer because they directly help maintain water balance by regulating water uptake from the soil and water loss through transpiration.