Bio CH6 F5 Studywithadmin

6.
1 Structure of a flower
1. the structures of flower
2. Comparison of male structure and female structure in a flower.
Male structure Female structure

Produces gametes
Aspect
Consists of anther and
filament Structure Consists of stigma, style
and ovary
Produces pollen grains
Function Receives pollen grains
and produces
ovule
Male gametes are
formed in pollen grains Formation of Female gametes are
formed in ovule
gametes
6.2 Development of Pollen
Grains and Embryo Sac
1. The Formation of Pollen Grains in an Anther
Anter mempunyai empat pundi debunga di mana debunga akan terhasil di

1 dalam pundi debunga.
2 Setiap pundi debunga mengandungi banyak sel induk debunga (2n).
Setiap sel induk debunga (2n) mengalami meiosis untuk menghasilkan tetrad
3 yang mengandungi empat sel haploid (n).
4 Sel haploid dalam tetrad berpisah membentuk debunga
Setiap sel haploid mengalami mitosis membentuk sel penjana (n) dan nukleus
5 tiub (n).
2. The Formation of Embryo Sac in an Ovule
Ovule is formed from ovum. Each ovule contains one embryo sac mother cell
1 (2n).
The embryo sac mother cells (2n) undergoes meiosis to form four
2 megaspores (n).
3 Three megaspores degenerated and remaining one megaspore
4 The remaining megaspore undergoes mitosis three times to

form seven cells with eight nuclei.
• Three cells move to one end near to micropyle, forming two synergid cells
5 and one egg cell .
• Three more cells move to another end to form three antipodal cells .
• One cell with two nuclei located at the center to form polar nuclei .
• The structure formed is known as embryo sac which is protected by
integument.
6.3 Pollination and Fertilisation
1. the formation of pollen tube and male gametes.
The wall of anther from mature pollen will

1 dry, shrink dan split. Pollen grains in the
pollen sac are released.
2 The released pollen grains are transferred

to the stigma of the same flower or different
flowers by pollinating agent.
The pollen grains that have been transferred

3 to the stigma will germinate and form a
pollen tube. The pollen tube grows down
towards the ovule through the style.
4 The generative nucleus will move along the

pollen tube towards the ovule. At the same
time, the generative nucleus will divide by
mitosis to form two male gametes (n).
The end of the pollen tube will secrete an

5 enzyme to digest the tissues of the style.
When it reaches the embryo sac, the pollen tube will penetrate the ovule
6 through the micropyle. The tube nucleus will degenerate and both male gametes
enter the embryo sac.
Double Fertilisation in the Formation of Diploid Zygote and
Triploid Nucleus
Importance of Double Fertilisation for the Survival of

Flowering Plants
• Produces diploid zygote to ensure the species genetic content is maintained

• Produces triploid endosperm nuclei to store food for seed germination
• Ensure development of endosperm tissue only in the fertilised ovule
• Create variation through meiosis and random fertilisation of gametes
6.4 Development of seeds and
fruits
1. Only the fertilised ovule will develop into a seed .
2. Double fertilisation stimulates ovary wall to enlarges and develop to
form fruit.
Part of flowers Part of fruits

Ovule • Seed
• Diploid zygote forms embryo which contains
plumule, radicle and cotyledon
• Triploid endosperm forms endosperm tissue to store
food for growing embryo and seed germination
• Integument forms testa to protect seed
Ovary wall Pericarp
• Ovary wall which consists of epicarp, mesocarp and
endocarp
• Epicarp is the skin of fruit
• Mesocarp is the flesh of fruit for most types of
fruits
• Endocarp surrounds seed
Petal, stamen and Degenerate
style
6.5 Importance of seeds for
survival
1. Seeds are protected by testa from any threat to embryo.
2. Embryonic activities of seed are suspended until the surrounding
factors are favourable for germination .
3. Seeds can be dispersed by dispersal agents such as wind, water,
insects, animals and humans to new habitats for germinating and
grow.

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6.

2. Comparison of male structure and female structure in a flower.

Male structure Female structure

Anter mempunyai empat pundi debunga di mana debunga akan terhasil di

2 Setiap pundi debunga mengandungi banyak sel induk debunga (2n).

4 Sel haploid dalam tetrad berpisah membentuk debunga

3 Three megaspores degenerated and remaining one megaspore

4 The remaining megaspore undergoes mitosis three times to

The wall of anther from mature pollen will

2 The released pollen grains are transferred

The pollen grains that have been transferred

4 The generative nucleus will move along the

The end of the pollen tube will secrete an

Importance of Double Fertilisation for the Survival of

• Produces diploid zygote to ensure the species genetic content is maintained

Part of flowers Part of fruits

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