What role does capillary action play in the physiology of plants and animals?

• A. It prevents water from entering plant roots and animal tissues.
• B. It breaks down water molecules into hydrogen and oxygen for cellular respiration.
• C. It causes water to evaporate more quickly from leaves and skin.
• D. It enables the upward movement of water through plant stems and helps transport fluids in small blood vessels.

Answer: (D)

Verified step by step guidance

1. Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of external forces, such as gravity. This phenomenon occurs due to the cohesive forces between water molecules and adhesive forces between water and the walls of the narrow tubes.
2. In plants, capillary action plays a critical role in the upward movement of water through the xylem, which are specialized vessels in the stem. Adhesion allows water molecules to stick to the walls of the xylem, while cohesion ensures that water molecules pull each other upward as they move.
3. Capillary action is also essential in animals, particularly in the transport of fluids through small blood vessels, such as capillaries. The narrow diameter of capillaries facilitates the movement of blood and nutrients to tissues, aided by the adhesive and cohesive properties of water.
4. This process is driven by the combination of capillary action and other forces, such as transpiration in plants and blood pressure in animals, which help maintain fluid movement.
5. Understanding capillary action highlights its importance in maintaining hydration and nutrient transport in both plants and animals, ensuring their survival and proper physiological function.