LIFE SCIENCE

Detailed explanation-1: -The lateral meristem tissues are responsible for the secondary growth of plants. The secondary growth of plants increase in stem thickness and it is due to the activity of the lateral meristems, which are absent in herbs or herbaceous plants.

Detailed explanation-2: -The thickening of the stem that occurs in secondary growth is due to the formation of secondary phloem and secondary xylem by the vascular cambium, plus the action of cork cambium, which forms the tough outermost layer of the stem. The cells of the secondary xylem contain lignin, which provides hardiness and strength.

Detailed explanation-3: -In botany, secondary growth is the growth that results from cell division in the cambia or lateral meristems and that causes the stems and roots to thicken, while primary growth is growth that occurs as a result of cell division at the tips of stems and roots, causing them to elongate, and gives rise to primary tissue.

Detailed explanation-4: -The correct option is A trunk. The thickened stem of a tree that supports branches and has a woody outer bark is called the trunk of a tree.