Final answer:
The region of elongation is where cells grow significantly in length, contributing to the lengthening of the root as they are produced by the root apical meristem.
Step-by-step explanation:
The region of elongation in a plant root is crucial to the root's growth in length. This region is where newly formed cells from the root apical meristem increase in size. In the elongation zone, cells expand the most in the distal/proximal direction, meaning they elongate up/down assuming the root is vertical. This expansion results in the root primarily growing longer, rather than wider.
It's important to note that while the cells are produced in the zone of cell division near the root tip, it's the elongation zone where these cells undergo significant growth in length.
Therefore, the elongation region contributes to the overall lengthening of the root, which is essential for the plant to anchor itself more firmly and access water and nutrients from deeper layers of soil.