National League for Nursing (NLN) Science Practice Exam

Which process is primarily responsible for moving water and solutes from the roots of a plant to its leaves?

1. Transpiration

2. Diffusion

3. Osmosis

4. Active transport

The correct answer is: Transpiration

Transpiration is the process primarily responsible for moving water and solutes from the roots of a plant to its leaves. This occurs when water vapor exits the plant through small openings called stomata, primarily located on the leaves. As water evaporates from the leaves, it creates a negative pressure within the plant's xylem vessels, which acts like a vacuum, pulling more water upward from the roots through capillary action and cohesion. In this context, transpiration not only facilitates the movement of water but also aids in the transportation of dissolved nutrients and minerals from the soil through the plant's vascular system. This process is essential for maintaining plant turgor, enabling nutrient delivery, and supporting photosynthesis, which occurs in the leaves using the water and carbon dioxide absorbed. The other processes, while important in their own right, do not primarily drive the movement of water and solutes in the same manner. Diffusion refers to the movement of molecules from areas of higher concentration to lower concentration and is more relevant for the movement of gases, while osmosis specifically deals with the movement of water across a semi-permeable membrane. Active transport involves the movement of molecules against their concentration gradient, requiring energy, which plays a role in nutrient uptake rather than the