Class X-D

Snehal Bhargava (34)

SEXUAL REPRODUCTIONIN

FLOWERING PLANTS

WHAT IS REPRODUCTION?

A biological processes are the processes of a living organism. They include

respiration, nutrition, reproduction etc.

Reproduction is the biological process by which new

individual organisms are produced from their parents through sexual or asexual

processes

REPRODUCTION

PLANTS ANIMALSASEXUAL SEXUAL

PLANTS

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Vegetative Propagation

Budding

Fragmentation

Spore Formation

SEXUAL REPRODUCTION IN PLANTS

The plants in which the sex organs are carried within the flowers and the seeds are enclosed in a fruit

are called angiosperms.

They are commonly known as flowering plants and reproduce by Sexual Reproduction which means – two

sexes (Male & Female).The sex or reproductive organs of the plant are in its

flowers.

The function of a flower is to make male and female gametes and to ensure that fertilization takes place to

make new seeds for reproduction of plant.

EX:- Apples, oranges, lemons and tomatoes are all Angiosperms

PARTS OF A FLOWER

PARTS OF A FLOWER

Receptacle – The base of a flower to which all the parts of a flower are

attached.

Sepals – The green, leaf like parts in the outermost circle of a flower. All the sepals

taken together are called ‘calyx’. The function of sepals is to protect the flower in its initial stages when it is in the form

of bud.

Sepals

Petals – The colorful parts of flower are called petals. All the petals taken together are

called ‘corolla’. The function of petals is to attract insects (for pollination) and to

protect the reproductive organs which are at the centre of the flower.

Petals

Stamen – Stamen is the male reproductive organ of the plant. Stamen produces pollen grains. The pollen contains the male gametes of the

plant. The stamen is made of two parts: A filament and an anther. The stalk is called a filament and the swollen top of stamen is

called anther.

Anther

FilamentStamen

Stigma

Style

Ovary

Carpel

Carpel – Carpel is the female reproductive part of the plants. It is a flask-shaped organ. A carpel is made of three parts: stigma, style and ovary. The top part of

carpel is called stigma. Stigma is for receiving the pollen grains from the anther (during pollination). Stigma is sticky so that pollen can stick to it. The middle part of carpel is called style. Style tube

connects stigma to the ovary. The swollen part at the bottom of a carpel is called ovary. The ovary makes ovules and stores them. Ovules contain the female

gametes of the plant . The female gametes of a plant are made in the ovary of carpel. Carpel is also called

pistil.

TYPES OF FLOWERSUnisexual Flower – A flower having either

stamen or pistil. A flower having only stamens is said to be staminate, or male. A flower having only carpel is said to be carpellate, or female.

Example: Melon, Papaya etc.

Bisexual Flower – A flower having both stamen and pistil. These flowers are called perfect

flowers.Example: Lily, Peas, Passion Flower etc.

THE STEPS OF SEXUAL REPRODUCTION IN PLANTSThe male organ of flower called “stamen” makes the

gametes (male sex cells) of the plant. These male gametes are present in the pollen grains.

The female organ of a flower called “carpel” makes the female gametes (female sex cells) of the plants. These

female gametes are present in ovules. The female gametes present in ovules are also called ‘ova', 'egg

cells', or just ‘eggs’.The male gametes present in pollen grains fuse with the

female gametes or egg cells present in ovules to form a zygote.

The fertilized egg cells grow within ovules and become seeds.The seeds produce new plants on germination under suitable

conditions.

POLLINATIONFor the male gamete to be able to

combine with the female gamete, it is necessary that first the pollen grains

from the anther of stamen is carried to the stigma of carpel.

The transfer of pollen grains from the anther to the stigma is called

pollination.

Pollination is done by insects, bird, wind, and water.

Pollination can occur in two ways: Self Pollination and Cross Pollination.

Self Pollination: Transfer of pollen grains from the anther of a flower to the

stigma of the same flower or another flower on the same plant, is called self

pollination.

Cross Pollination: Transfer of pollen grains from the anther of a flower to the stigma

of a flower on another similar plant is called cross pollination.

FERTILISATION

reproduction in flowers.mp4

After pollen grains fall on stigma, the next step is fertilization. Fertilization occurs when the male gamete

present in pollen grain joins with the female gamete present in ovule.

When a pollen grain falls on the stigma of the carpel, it burst open and grows a pollen tube downwards through

the style towards the female gamete in the ovary.

A male gamete moves down the pollen tube. The pollen tube enters the ovule in the ovary. The tip of pollen tube

burst open and male gamete of pollen combines with nucleus of female gamete or egg present in the ovule to form a fertilized egg (or zygote). And thus fertilization

has taken place.

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FORMATION OF FRUIT

Fruit Development.mp4

The fertilized egg (or zygote) divides several times to form an embryo within the ovule.

The ovule develops a tough coat around it and is gradually converted into a seed (containing the baby

plant).

In fact, all the eggs in the ovules present in the ovary of a flower get fertilized by male gametes from pollen grains

and grow to become seeds.

The flower develops and becomes a fruit and protects the seeds.

The other parts of flower like sepals, petals, stamens, stigma and style dry up and fall off. Only the ovary is left

behind. So, at the place on plant where there was a flower originally, is a fruit.

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SEEDA seed is the reproductive unit of a

plant and can be used to grow a new plant.

The seed contains a baby plant (or embryo) and food for the baby plant.

The part of baby plant in seed which develops into shoot with leaves is called

Plumule and the part which develops into root is called Radicle.

The part of seed which contains stored food for the baby plant is

called Cotyledon.

The baby plant present inside a seed is in the inactive state called Dormant

State.When the seed gets suitable conditions

like water, air and warmth, etc. it germinates and a new plant grows out

of seed.

This way, the parent plant reproduces more plants like itself by forming seeds

through flower.

GERMINATION OF SEEDThe seeds obtained from a plant are usually

very dry. In this dry state, the seeds can remain alive but inactive for long periods and are said to be dormant. When a seeds gets water, air and warmth, etc., it begins to grow. When a seed begins to grow, it is aid to germinate.

Thus, the beginning of the growth of seeds is called germination of seeds.

Germination begins when the seeds absorbs water, swells and bursts through the seed coat. The water helps the enzymes to function in the

seed.

The enzymes digest the stored food in cotyledons and make it soluble. This soluble food makes the radicle and plumule present in the seed to grow.

The radicle of the seed grows first to form the root. The root pushes down into the soil and

begins to absorb water and minerals from the soil. After this the plumule grows upwards to form

the shoot.The shoot and root grow further. When the shoot comes up above the ground, it develops green

leaves. The seedling grows gradually and ultimately becomes a new plant.