OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What process draws water into root hair cells from the soil?

1. Diffusion

2. Active transport

3. Osmosis

4. Endocytosis

The correct answer is: Osmosis

The correct answer is osmosis, which is the process through which water moves across a selectively permeable membrane. In the context of root hair cells, osmosis occurs when water from the soil moves into the cells due to differences in water potential. The soil typically has a higher concentration of water (lower solute concentration) compared to the interior of the root hair cells, which may have a higher concentration of solutes (like minerals and nutrients). As a result, water naturally moves from the area of higher water concentration (the soil) into the area of lower water concentration (inside the root hair cells) through osmosis. This process does not require energy, as it relies on the passive movement of water molecules, which is driven by the concentration gradient. Understanding osmosis is fundamental in biology, especially in plant physiology, because it explains how plants absorb water and maintain turgor pressure, which is crucial for their structure and overall health.