A Level Biology Practice Exam

What is root pressure?

1. The movement of water via capillarity

2. The active transport of sugars in the roots

3. The pumping of minerals into the xylem resulting in water movement by osmosis

4. The process of photosynthesis in roots

The correct answer is: The pumping of minerals into the xylem resulting in water movement by osmosis

Root pressure is primarily related to the process by which minerals are actively transported into the xylem from the root cells, which leads to water movement through osmosis. When solutes like minerals are concentrated in the root xylem, water follows these solutes into the xylem vessels due to osmotic gradients. This creates a pressure that can push water upward through the plant, contributing to the overall movement of water and nutrients from the roots to the leaves. The correct understanding highlights the role of root pressure in the hydrating process of plants, supporting their physiological functions. Other options focus on different processes that do not accurately define root pressure. Capillarity, for instance, refers to the ability of water to flow in narrow spaces without external forces, which is a separate physical mechanism. The active transport of sugars in roots, while a vital process, pertains to translocation rather than root pressure. Lastly, photosynthesis primarily occurs in the leaves, not in the roots, making that option unrelated to the concept of root pressure.