A Level Biology Practice Exam

What does phloem transport in plants?

1. Water and minerals

2. Products of photosynthesis

3. Oxygen and carbon dioxide

4. Nutrients and waste products

The correct answer is: Products of photosynthesis

Phloem plays a crucial role in the transport system of plants, primarily responsible for moving the products of photosynthesis, which are mainly sugars, from the leaves where they are produced to other parts of the plant, such as roots, stems, and fruits. This process is vital for the growth and development of the plant as it distributes energy-rich compounds needed for cellular respiration and the synthesis of other necessary organic materials. Unlike the other options, which refer to different types of transport within plants, phloem specifically facilitates the movement of organic compounds. The transport is driven by a pressure flow mechanism, allowing the plant to efficiently allocate its resources based on metabolic demands. In contrast, water and minerals are primarily transported by xylem, while gases like oxygen and carbon dioxide are exchanged through stomata during processes like photosynthesis and respiration. Nutrients and waste products have varied transport mechanisms depending on their nature and the plant’s physiological needs, making the role of phloem distinct in focusing solely on the sugars produced during photosynthesis.