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

What benefit do roots receive from growing away from light?

1. They access oxygen directly from the air

2. They absorb nutrients and water from the soil

3. They minimize competition with other plants

4. They enhance photosynthesis through deeper growth

The correct answer is: They absorb nutrients and water from the soil

Roots grow away from light as a strategy to maximize their access to essential resources found in the soil, primarily water and nutrients. The soil is a rich source of minerals and organic material that support the plant's growth and development. By growing deeper into the soil, roots can more effectively absorb moisture, minerals, and other nutrients that are critical for the plant's metabolic functions. The other options do not accurately reflect the primary benefit of roots growing away from light. For instance, while access to oxygen is important, roots typically acquire oxygen from the spaces in the soil rather than directly from the air, which is more relevant to a plant's shoot system. Minimizing competition is also not a direct benefit of roots growing away from light since this growth is primarily a response to the root's needs rather than to the presence of other plants. Lastly, enhancing photosynthesis through root growth is not applicable because photosynthesis occurs in the green parts of the plant exposed to light, not in the roots. Thus, the focus of root growth is primarily to secure a more abundant supply of water and nutrients from the soil.