Structure of a leaf

 

Structure of a leaf

 

Photosynthesis

Photosynthesis is how leaves make food from light, using chlorophyll to turn water and carbon dioxide into oxygen and glucose.

The photosynthesis equation is:

 

Carbon dioxide + water → glucose + oxygen

Leaves are adapted for photosynthesis in several ways.

 

Plant adaptation	Function
Broad leaves	Maximize sunlight absorption
Thin leaves	Shorten gas diffusion distance
Network of tubes	Transport water, minerals and glucose (or food)
Lots of chloroplasts	Trap sun energy with chlorophyll
Stomata	Allow gas exchange in and out of leaf
Guard cells	Control stomata opening and closing
Midrib	Strengthen and support the leaf
Petiole	Connect the leaf to the stem

 

 

Light

Leaves have a large surface area and a waxy layer to absorb and protect light. The upper part has palisade cells with many chloroplasts and a tall shape to catch more light.

 

Carbon dioxide

Leaves take in carbon dioxide from the air through stomata, small holes on the underside. Guard cells adjust the stomata size to prevent water loss. The lower part has spongy cells with air spaces to let carbon dioxide reach other cells and oxygen leave.

 

Water

Leaves get water from the roots through tubes. The roots have root hair cells that stick out into the soil and have a big surface area and thin walls to absorb water easily.

Root cells have no chloroplasts, as they are in the dark and cannot do photosynthesis.

 

Summary:

 

• Leaves are vital plant organs that make food by photosynthesis.
• Leaves come in various sizes, shapes and colours to suit photosynthesis.