A Level Biology Practice Exam

What is the main function of the phloem in plants?

1. To transport root minerals

2. To carry water from roots to leaves

3. To distribute the products of photosynthesis

4. To provide structural support

The correct answer is: To distribute the products of photosynthesis

The primary function of phloem in plants is to distribute the products of photosynthesis, mainly sugars such as sucrose, from the leaves where they are produced to other parts of the plant, including roots, fruits, and developing leaves. This process, known as translocation, is vital for plant growth and development, as it ensures that energy stored in the form of sugars reaches areas where it is needed for growth, storage, and energy for metabolic processes. Phloem consists of specialized living cells that facilitate this transport, allowing for bidirectional movement of nutrients depending on the plant's needs. This is crucial not only for sustaining the plant but also for enabling processes like reproduction and fruit/seed development. In contrast, the roles associated with minerals and water transportation are predominantly carried out by the xylem, which specifically transports minerals and water from the roots to the leaves. Additionally, while providing structural support is essential for a plant, this function is generally attributed to other tissues such as lignified xylem or specialized supportive cells rather than phloem.