AP BIOLOGY

Detailed explanation-1: -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-2: -Indeterminate Plant Growth: Meristems Meristematic tissues consist of three types, based on their location in the plant. Apical meristems contain meristematic tissue located at the tips of stems and roots, which enable a plant to extend in length.

Detailed explanation-3: -Stems undergoing primary growth are those where the increase in length and thickness depend on the apical shoot meristm and intercalar meristem activities. Stems showing secondary growth increase in diameter by the activity of the vascular cambium and cork cambium. All plant species perform primary growth.

Detailed explanation-4: -Vascular plants, which account for over 90% of the Earth’s vegetation, all undergo primary growth-which lengthens roots and shoots. Many land plants, notably woody plants, also undergo secondary growth-which thickens roots and shoots. Primary and secondary growth can occur simultaneously in a plant.

Detailed explanation-5: -Elongation Phase-These cells elongate due to enlargement of the vacuole present in the cell and hence that zone is called the zone of elongation. The cell enlargement and new cell wall formation take place in the cells present in the elongation phase. Modifications like larger vacuoles take place in the cells here.