Plant organ
The main plant organs are:
Root
Anchors the plant in the soil.
Absorbs water and minerals.
Stores food in some plants.
Stem
Supports the plant.
Transports water, minerals, and food between roots and leaves.
Holds leaves, flowers, and fruits.
Leaf
Makes food by photosynthesis.
Exchanges gases through tiny pores called stomata.
Loses excess water through transpiration.
Flower
The reproductive organ of flowering plants.
Produces seeds after fertilization.
Attracts pollinators.
Fruit
Develops from the flower after fertilization.
Protects the seeds.
Helps in seed dispersal.
Seed
Contains the embryo (young plant).
Stores food for the embryo.
Germinates to form a new plant under suitable conditions.
The waxy cuticle is a thin, waterproof layer on the surface of leaves.
Main function:
It reduces water loss from the leaf by evaporation.
It also:
Protects the leaf from damage.
Helps stop harmful microorganisms from entering.
Makes the leaf surface waterproof.
In desert plants, the waxy cuticle is usually much thicker than in plants living in wetter places.
Why? Desert plants need to save as much water as possible because water is scarce.
Example: Cactus plants have a thick waxy coating that helps prevent water from escaping.
The upper epidermis is the top layer of cells on a leaf.
The upper epidermis is made of a single layer of tightly packed cells.
10. Spongy mesophyll
The spongy mesophyll is a layer of cells inside the leaf, below the palisade mesophyll.
Function:
Helps with gas exchange.
Contains air spaces that allow carbon dioxide and oxygen to move around the leaf.
Its cells also carry out some photosynthesis.
Made of: Loosely packed cells with many air spaces.
Inside the spongy mesophyll, water can evaporate from the moist surfaces of the cells into the air spaces. The water vapour then moves out through the stomata.
A stoma (plural: stomata) is a tiny pore or opening in the leaf surface.
12. Guard cells are two special cells that surround each stoma.
13. A vascular bundle is a group of transport tissues in a plant that carries materials around the plant.
12. The lower epidermis is the bottom layer of cells on a leaf.
Its functions are:
Protects the inside of the leaf.
Contains many stomata, which allow gases to enter and leave.
Helps control water loss through the stomata.
Made of: A layer of tightly packed cells, usually covered by a thin waxy cuticle.