Grade 3 Science(NSO) : Leaf

Functions of a leaf

Absorbs sunlight

Help in exchange of gases

Carries out photosynthesis

Apex : Tip of leaf

Base : Attaches to petiole ; if petiole is absent attaches directly to stem

Margin : Edge of leaf

Viens : Transports water, nutrients and food. Made of xylem and phloem.

Epidermis : External layer of leaf (protective) . Prevents water loss and over heating of leaf.

Stomata : Control the entry and exit of gases into and outside the leaf

Mesophyll : Photosynthesis occurs here.


Features of leaves

Adaption Purpose
Large surface area To absorb more light
Thin Short distance for carbon dioxide to diffuse into leaf cells
Chlorophyll Absorbs sunlight to transfer energy into chemicals
Network of veins To support the leaf and transport water and carbohydrates
Stomata Allow carbon dioxide to diffuse into the leaf



Photosynthesis: How Plants Make Food and Energy?


Plants take water from the soil through their veins, which are called xylem. The water goes to the leaves. The leaves take carbon dioxide from the air into the plant. The carbon dioxide mixes with the water. Energy from the sun helps this process along and turns the combination into a sugar called glucose. The glucose is plant food. It gives the plants energy to grow.

Facts about Photosynthesis 

    • Leaves of a plant have a substance called chlorophyll. It makes leaves green. It also traps the energy from the sun so that the plant can use it.
    • When plants take in carbon dioxide from the air, they release oxygen. Animals use this oxygen to grow. We release carbon dioxide, which the plants use.
    • The exchange of oxygen and carbon dioxide in the leaf (as well as the loss of water vapor in transpiration) occurs through pores called stomata (singular = stoma).Normally stomata open when the light strikes the leaf in the morning and close during the night.
    • Plants also need  minerals  from the soil to grow , Nitrogen helps them grow and make leaves. Phosphorus helps grow strong roots. Potassium helps the plant make fruits and also keeps them healthy.
    • Plants need large amounts of nitrogen, phosphorus and potassium. The soil doesn’t always have enough of these nutrients. Gardeners use fertilizer to give plants more nutrients. Some fertilizers are made from chemicals. Others are made from natural things like cow manure.

Photosynthesis Vocabulary