Page 57 - Viva ICSE Science 5 : E-book

Fertilisation
pollen grain
Pollen grains land on stigma and produce a tube called
pollen tube. This tube carries the male gamete through

the style to the ovule. pollen tube

Ovule contains the female gamete. The male gamete ovary
combines with the female gamete to form a new cell called ovule

zygote. The process of combining of male and female
gametes is called fertilisation.
Fertilisation

Formation of fruit and seeds

• After fertilisation, the sepals, petals and other parts, except the ovary, dry and fall off .

• Once the zygote is formed, it divides rapidly to form an embryo.

• When the zygote begins to divide and grow, the ovary begins to develop as fruit.
The ovules start developing as seeds.

• The embryo, thus formed, has two leaf-like cotyledons and is surrounded by the
protective seed coat (seed coat develops from the ovule wall).

• The embryo contains the cells which later develop into a plant.

ACTIVITY TIME

To study the structure of seed

Let’s understand the structure of a seed through an activity.
• Take some gram or bean seeds and soak them in water for 2–3 days.

• Now take out a seed and observe it carefully. seed coat
cotyledons
• You will see an outer skin-like covering that has swelled up.
This is known as the seed coat. Its main function is to protect
the seed. If you remove this, you will fi nd seed leaves, also
known as cotyledons. Their main function is to provide food
to the growing plant. On separating these cotyledons, you
will observe a baby plant inside. It is this baby plant which
grows into a seedling. Structure of a seed

Germination

The process by which a seed develops into a seedling or a young plant is called
germination.

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