Structure of a leaf

Structure of a leaf

2.1 Structure of a leaf

Main organ that carries photosynthesis

Divided into two parts external and internal structure.

External structure

Lamina

Flat, thin, smooth and green part of the leaf.

Flat shaped to provide wide surface for exposure of chloroplast containing cells to maximum sunlight.

Thin to allow gases to diffuse in an out efficiently

External structure

Petiole

Stalk that connects leaf to the stem.

Stretches out into the lamina to produce middle veins to support lamina.

Internal structure of a leaf lamina

cuticle

• waxy, waterproof, transparent covers the upper and lower part

• reduces water loss through transpiration

• transparent to allow light to pass through

upper epidermis

• upper surface of the leaf

• does not contain chloroplast

• transparent

lower epidermis

• lower surface of the leaf

• consist of stomata guarded by a pair of guard cells

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Palisade mesophyll cells

• vertically arranged

• closely packed

• site for photosynthesis

• contain many chloroplasts

spongy mesophyll cells

• irregular shaped to increase intrnal surface area for gas exchange

• loosely arranged

• ease carbon dioxide and water absorption throught the leaves for photosynthesis

• less number of chloroplast

vascular bundle

• xylem - transports water and mineral salts absorbed from root to the leaf.

• xylem - walls are lignified and thickened to provide mchanical support.

• pholem - transports organic subtances to other parts of th plants.

Differences between monocot and dicot

Draw a table with two columns in your pages and list the difference between a monocot and a dicot. Give at least 5 differrences.