Final answer:
The root cap covers the apical meristem and secretes a lubricating substance to aid root growth in soil. It is replaced as it wears away while the root advances through the soil.
Step-by-step explanation:
The root cap covers the apical meristem at the tip of the root and produces a lubricating substance so roots can grow more easily in the ground. The root cap consists of specialized cells that protect the growing tip of the plant root by secreting a slimy substance to ease the root's movement through the soil. Moreover, as the root pushes through the soil, the cap gets worn away and continuously replaced. Just above the root cap is the primary meristem, where growth in length occurs due to cell division.
The root tip can be categorized into three zones: the zone of cell division, the zone of elongation, and the zone of maturation and cell differentiation. The root hairs are also important structures that arise just after the zone of elongation; they are extensions of root epidermal cells and assist in increasing the root's surface area for effective water and mineral absorption.