Tissues — Science STD 9 — Question

Simple tissues: These tissues are composed of cells which are structurally and functionally similar.

There are three types of simple tissues:

1. Parenchyma: Parenchyma cells are living and posses the power of division. The cell wall is thin and encloses a dense cytoplasm which contains a small nucleus and surrounds a large central vacuole.

2. Collenchyma: It tissues also consists of living cells. It is characterized by the deposition of extra cellulose at the corners of the cells. In collenchymas, intercellular spaces are generally absent. Collenchyma cells are elongated in shape. They often contain a few chloroplasts.

3. Sclerenchyma: Sclerenchyma cells are dead cells and they are devoid of protoplasm. The cells walls of sclerenchyma are greatly thickened by the deposition of lignin. The cells of sclerenchyma are closely packed without intercellular spaces.