Reproduction

REPRODUCTION

UNIT

4Classifying plants

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SEEDLESS PLANTS

GYMNOSPERMS ANGIOSPERMS

are classified as

which can be

PLANTS WITHSEEDS

PLANTS

Natural Science 2. Secondary Education

PARTS OF A PLANT Flower is the reproductive

unit of a plant Calyx

Green sepals which protect the development of the flower

Corolla Petals Glands at the bases secrete

sweet, fragrant nectar that attract insects.

Stamen Male reproductive organ Made up of the stacks

(filament) and sacks (anthers)

Pollen stored in anthers Pistil

Female reproductive organ of the flower

Contains an ovary, a style, and a stigma

anther

pollen grains

anther

filament

stamen

sepals (calyx)

stigma

style

ovary

ovules

pistil

petals(corolla

)

Cal-icks

Sep-uls

kor-oh-lah

Stay-mun

An-thurs

Pis-tul

Kar-puls

Stig-mah

• It is made up of stamens. Each stamen has:

• A filament to support the anther.

• An anther, where pollen grains develop. Male gametes form inside these grains.

The androecium

Anther

Pollen grains

FilamentGo back to the Start menu

Parts of a typical flowerUNIT

4


• This is the female reproductive organ. It is shaped like a bottle.

• It has three parts:

• Ovary: the widest part, which contains the female gametes.

• Style: the long part.

• Stigma: the tip.

The gynoecium

Ovary

Style

Female gamete

Stigma

Parts of a typical flowerUNIT

4

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POLLINATION

Transfer of pollen grains, stored in the anther of the stamen, to the stigma of the pistil.

Occurs by wind or by insects, such as bees and butterflies.

• Pollen grains are transported by the wind.

• For this reason, the flowers are not attractive (as they do not need to attract animals), and they produce a lot of pollen (because only a little reaches other flowers in the wind).

Anemogamous pollination

Unattractive flowers

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Types of pollinationUNIT

4


• Pollen grains are transported by insects.

• Therefore, plants have attractive flowers and produce sweet substances like nectar to attract insects.

Entomogamous pollination

Attractive flowers that produce nectar

Types of pollinationUNIT

4

Go back to the Start menuNatural Science 2. Secondary Education

FERTILIZATION Once pollen grain lands on

the pistil, pollen tubes form until they reach the ovary.

Fertilization occurs in the ovary once the male gamete (pollen) and female gamete (ovule) unite into a zygote.

Ov-you-al

pollen tube

Fertilisation

Pollination occurs.

When the pollen grain reaches the flower’s stigma it forms a pollen tube, which grows along the style until it reaches the ovary.

Male gametes travel down the pollen tube to the ovary and fertilisation takes place.

Female gamete

Male gametes

Pollen tube

Pollen grain

11

22

33

UNIT

4

Natural Science. Secondary Education, Year 2

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Reproduction