A Level Biology Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

The correct association for sieve plates is with the flow between phloem cells that allows the transport of nutrients and sugars throughout the plant. Sieve plates are specialized structures found in the phloem tissue, specifically at the ends of sieve tube elements. They enable the movement of phloem sap by facilitating the passage of the fluid containing sugars and other organic compounds from one sieve tube element to another. This is crucial for the overall function of the phloem system, which is essential for the distribution of energy and resources in plants.

The other options are associated with different functions and cell types. Cortex cells in the stem are primarily involved in storage and transport, not specifically linked to phloem transport. Water uptake is related to root cells but does not pertain to sieve plates. Gas exchange is a function of stomata in leaves, again unrelated to the role of sieve plates in nutrient transport within the phloem.