Page 3 - ACTIVE SCIENCE 4 TOC

S tructure of a Leaf

A leaf is mostly a green, flattened

structure attached to the stem. The Veins Blade
leaves are also called the food factories
of plants. The flat broad part of a leaf is Midrib

called the lamina or blade. The single
leaf blade connected to the stem is called
the petiole. The leaf, has an outer waxy Petiole
protective coating called the cuticle.
There are several veins in a leaf and the Parts of a Leaf

main vein is called the midrib. These veins
carry water and nutrients within the leaf. Closed stomata

Like humans, plants also breathe. They
do it through tiny openings present on

the surface of leaf called stomata. The
stomata open and close to allow the
exchange of gases like carbon dioxide and
the oxygen. Stomata also control the loss

of water through leaves. The opening and
closing of stomata is controlled by the Open stomata
bean-shaped guard cells.
Stomata on the Surface of Leaf

H ow Do Plants Prepare Their Food?

Plants make their own food through the
process of photosynthesis. Leaves are the
Oxygen
sites of photosynthesis. The photosynthesis
occurs in the chloroplasts, the tiny
structures located in the cells of leaves and
Energy from Food green stems. The chloroplasts contain a

sunlight green coloured pigment called chlorophyll.
It is this chlorophyll which traps sunlight.

Carbon Thus, the things which are necessary for a
dioxide plant to carry out photosynthesis are:

• Carbon dioxide • Light
Water
• Water • Chlorophyll

Plants make their own food in the form
Photosynthesis in Plants of sugar or glucose by absorbing the light

10 Active Science-4