Answer:
Primary plant growth increases the length of shoots and roots, while secondary growth results in an increased girth as layers of woody tissue are laid down.
Step-by-step explanation:
Primary growth is as a result of rapid cell division in the shoot apical and root apical meristem. Primary growth leads to an increase in the length of the shoot and the root.
Secondary growth is as a result of cell division in the lateral meristems (vascular cambium and the cork cambium) thereby making the root and stem thick. Secondary growth leads to an increase in thickness or girth of the plant as layers of woody tissue are laid down.