AP BIOLOGY

Detailed explanation-1: -The key to plant growth is meristem, a type of plant tissue consisting of undifferentiated cells that can continue to divide and differentiate. Meristem allows plant stems and roots to grow longer (primary growth) and wider (secondary growth).

Detailed explanation-2: -Growth in plants occurs as the stems and roots lengthen. Some plants, especially those that are woody, also increase in thickness during their life span. The increase in length of the shoot and the root is referred to as primary growth. It is the result of cell division in the shoot apical meristem.

Detailed explanation-3: -Apical meristem is present at the tips of growing roots and shoots. It increases the length of roots and shoots. Lateral meristem is present inside the roots and shoots in the form of a strip. It is responsible for the increase in the girth of roots and shoots.

Detailed explanation-4: -Meristems contribute to both primary (taller/longer) and secondary (wider) growth. Primary growth is controlled by root apical meristems or shoot apical meristems, while secondary growth is controlled by the two lateral meristems, called the vascular cambium and the cork cambium.