CHAPTER 3: CELLS(PART 2)

Biology

Cells, tissues, organs and organisms.Cells of the same kind grouped together form

Tissue.

Tissues of different kinds grouped together form

Organ.

Organs of different kinds grouped together form

Organ system.

All organs and organ systems in a living thing form

An organism (the body of the living thing)

Plants as living organisms

The tissues in the leaf work together and form an organ the leaf.

Upper epidermis

Palisade mesophyll

Spongy mesophyll

Lower epidermis

Waxy Cuticle

Stomata(Singular: stoma)

Xylem tissue

1) Epidermis• Form the outer covering of the plant.

• They are broad and flat and joined together.

2) Palisade mesophyll• They are under the upper epidermis.

• The function of this layer is to take sunlight and make food.

3) Spongy mesophyll• It is under the palisade layer.

• They are rounder and have gaps between them.

• Their task is to help bring water to the leaf for use in making food.

4)XYLEM TISSUE When water evaporates it is replaced by water drawn

up in tube like called xylem tissue. It forms much of the mid rib and veins in the leaf.

5)STOMATA They are specialized pairs of cells in the lower

epidermis of a leaf can bend to make an opening through which water vapour can escape from spongy mesophyll.

Stomata is the pleural while stoma is the singular.