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Module 31

Science and Health

Pollination and Fertilization

A DepEd-BEAM Distance Learning Program supported by the Australian Agency for International Development
 To the Learner

Do you know why insects are visiting the flowers? Have you
wondered how seeds are formed? This module will help you
understand how pollination and fertilization in flowers take place.
Have fun answering the questions and doing the activities.

Let’s Learn

Describe the process of pollination and fertilization in flowers

that lead to the development of seeds.
Identify parts of a flower that develop into fruits and seeds.
Identify agents of pollination.

Let’s Try This

A. Arrange the statements to show the process of pollination.

Write numbers (2-5) on the blank. Number 1 is done for you.
The pollen tubes grow down through the style.
The pollen grain lands to the stigma.
1 Pollen grains from the anther transfer to the stigma.
It germinates and grows pollen tube.
As the pollen tube grows down the style, the sperm cell
develops inside it.

B. Write each statement in the box to show the correct process

of fertilization in plants.
- Pollen tube bursts and sends out two sperm cell.
- The sperm cells will join the egg cell and the polar cell in the
ovule.
- The sperm cell travels down within the tube.

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 Let’s Study This

Take a look at the strip below and enjoy reading.

Flower making is like the landing lights on an airport

runaway. They guide the bee into the flower’s pollen grains.

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Reading 1

The transfer of pollen grains from the anther to the

stigma is called pollination. There are two kinds of
pollination, the self and cross pollination. Self-pollination
occurs when pollen grains transfer from the anther to the
stigma of a flower of the same flower or of another flower
on the same plant. Cross-pollination occurs when pollen
grains transfer from the anther to the stigma of a flower of
another plant.

The pollen grains attach to the stigma. Then they

germinate and grow pollen tubes. The pollen tubes grow
down through the style. As it grows down, the sperm cells
develop inside it.

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 As the pollen tube reaches an ovule, it bursts and
releases/discharges two sperms. One sperm fertilizes an
egg cell, other sperm fertilizes two female structures called
the polar nuclei. The union of the first sperm becomes a
zygote while the other one produces endosperm, the food
storage of the embryo. This is called double fertilization.
After fertilization, the ovules undergo changes and form
into seeds. As the seeds are forming, the stigma withers
and the petals and sepals drop off. The ovary enlarges to
form the fruit. The fruit is the fleshy ovary of a plant
enclosing the seed or seeds.

You have learned about the process of pollination and

fertilization. Now let’s find out what things help bring about
pollination.

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Reading 2

These are things that help bring about pollination.

They are called agents of pollination.

Insects are one of the agents of pollination. They look

for food in the flower in the form of nectar and pollens.
When they step or alight on the flower, the pollen grains
stick to their bodies and legs. When they visit another
flower, the pollen grains are transferred to the stigma of the
flower. Then pollination occurs. Most common pollinators
are bees, beetles, butterflies, moths and flies.

Another agent of pollination is the wind. Some flowers

have exposed stamens. When the wind blows on them,
pollen grains are scattered and some reached the stigma of
a flower.

Water is another agent. Plants growing on water can

be pollinated by pollen grains carried by water. The rain
can also carry pollen grains from the anther to the stigma.

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 Let’s Do This

A. Fill up the sequence chain to show how pollination happens.

Pollen grains Pollen grains Pollen As pollen

from ________ land to the tubes grow tubes grow
transfer to the ____________. down the
________. style, the
______________.
___________
develops
inside it.

B. Fill up the sequence chain to show the process of

fertilization.

Pollen tube One sperm cell The other

Reaches an unites with the sperm cell will
______________. join the
_____________
and bursts _______________
and sends out in the ovule
sperm cell.

Let’s Do More

A. Write C if the statement is correct and I if it is incorrect.

______ 1. Flowers produce sperm cells and egg cells.

______ 2. Fertilization in flowering plants is similar to fertilization
in animals.
______ 3. After pollination the sperm cell in the pollen grains
unites with the egg cell in the ovules.
______ 4. The ovules become the fruit.
______ 5. Wind, water and insects help in the process of
pollination.
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B. Solve the puzzle. Use the clues below.

2.

4.
1.

2.

3. 3.

4.

5.

Across

1. Insects are attracted to this part of a plant

2. Female reproductive organ of a flower
3. Transfer of pollen grains from the anther to the stigma
4. The part of the stamen that holds the pollen
5. An agent of pollination

Down

1. The Union of an egg cell and sperm cell

2. Ripened ovule
3. The part of the flower containing egg cell
4. It carries the sperm cell of a flower.

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 Let’s Remember This

I learned that:

pollination occurs when pollen grains from the anther

transfer to the stigma of a flower.

the two kinds of pollination are self-pollination and
cross-pollination. These are carried by insects,
animals, water, wind and people.

a pollen grain develops/grows a pollen tube the
moment it lands on the stigma and moves down to
the ovule. Then it bursts and sends out sperm cells
which will join the egg cell and polar nuclie in the
ovule. This is called double fertilization.

Only flowering plants from seeds through double
fertilization.

the fertilized ovules develop into seeds.

the ovary which contains the seed enlarges and form
the fruit.

Let’s Test Ourselves

A. Write each statement in the box to show the correct process

of pollination.
Pollen grains from the anther transfer to the stigma.
Pollen tube germinates.
Pollen grains land to the stigma.
Pollen tubes grow down through the style to the ovule. As it
grows down, the sperm cells develop inside it.

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B. Arrange the statements to show the process of fertilization.
Write numbers 1-3 on the blank.

Pollen tube bursts and sends out sperm cells.

The sperm cells will join the egg cell and the polar
nuclei or cell in the ovule.
The sperm cell travels down within the tube to the
ovule.

Science Fact File

Pollination is very important. It leads to the creation of new

seeds that grow into new plants. But how does pollination work?
Well, it all begins in the flower.

What about plants that don’t have flowers?

Some plants don’t have flowers. Cone-bearing plants, for
example, reproduce by means of spores that are produced by a
male cone and travel by wind to a female cone of the same
species. The seeds then develop in the female cone.

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 Answer Key

Let’s Try This

A. 4 B.
2 Pollen tube The sperm The sperm
bursts and cells travel cells will
1 sends out down join the egg
sperm cells. within the cell and the
3
tube to the polar nuclei
5 ovule

Let’s Do This
A. anther, stigma B. ovule
stigma egg cell
down polar nuclei
sperm cell

Let’s Do More
A. 1. C
2. I
3. C
4. I
5. C

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B.

Let’s Test Ourselves

A.

Pollen grains Pollen grains Pollen tube

from the Pollen grow down
land to the
anther tubes through the
stigma
transfer to the germinate style to the
stigma ovule, as it
grows
down the
sperm cells
develop
B. 2 inside it
3
1

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