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

What do root hair cells primarily absorb from the soil?

1. Carbon dioxide and water

2. Nitrates and minerals

3. Oxygen and sugars

4. Chlorophyll and sunlight

The correct answer is: Nitrates and minerals

Root hair cells are specialized structures on the roots of plants that greatly enhance their ability to absorb essential nutrients from the soil. The primary function of these cells is to take in water and dissolved minerals, which are crucial for the plant's growth and survival. The process begins with the root hair cells extending their small, hair-like projections into the soil, increasing the surface area available for absorption. Among the important minerals absorbed are nitrates, which are vital for plant nutrition as they are a primary source of nitrogen. Nitrogen is necessary for the synthesis of amino acids, proteins, and nucleic acids, all of which are fundamental to plant development and function. While carbon dioxide is absorbed through the leaves during photosynthesis, it is not taken up by root hair cells. Similarly, water is indeed absorbed, but nitrates and other minerals are the primary focus of root hair cell activity, as they directly contribute to the nutrient supply of the plant. Oxygen is used primarily in the process of respiration and is more readily available in the atmosphere rather than being absorbed through root hairs. Sugars, being the products of photosynthesis, are transported through the plant rather than absorbed by roots. Lastly, chlorophyll and sunlight are not absorbed by root hair cells at all