2. Sexual reproduction occurs in
angiosperms or flowering plants.
Flower is the reproductive organ of
the flowering plant.
4 basic parts of a flower:
(I) Sepal
(II) Petal
(III) Stamen
(IV) Pistil
3. Sepal and petal are non-reproductive
organs whereas stamen and pistil are
male and female reproductive organs.
Normally, a flower consists of both
male and female reproductive
structures.
6. Petal:
Often brightly coloured and scented.
Many have nectaries make nectar.
Draws attedtion of insects and animals.
Protects soft stamen and pistil.
Stamen:
Male reproductive system.
Also called the androecium.
Each one is made up of two parts:
a) Anther.
b)Filament.
7. Anther:
Structures that produces pollen grains.
Pollen grains consist of the male gametes.
Filament:
A long stalk which supports the anther.
Stigma:
A sticky structure at the apex of the style .
Place where pollen grains adhere.
8. Style:
A stalk that joins the stigma to the ovary.
Connects the stigma to the ovary.
Holds the stigma in the air to collect pollen.
May nourish pollen tube following pollination.
Ovule:
Contains female gametes.
Form the seeds.
10. Ovary:
Structures that protects ovules.
Forms the fruits.
Stores one or more ovules from which
the female gametes develop.
Receptacle:
Supports ovary.
It may swell and encloses the ovary to form
the certain part of fruits.
Examples: apple and strawberry.
11. 1) Pollen grains are formed in
the anther.
2) Each pollen mother cell will go
through meiosis to produce four
haploid microspores (n).
12. 3) A tube nucleus and generative
nucleus formed after the nucleus of
each microspore divides by mitosis.
4) The microspores develop into
pollen grains. Eventually the
microspores develop into pollen
grains.
13. 5) Pollination is the process in which
mature pollen grains from the anther
are transferred to the stigma of a
flower.
14. Formation of Embryo Sac
in the Ovule
1) The ovule develops from the ovarian tissue
at the base of the carpel.
2) It has a diploid embryo sac mother cell (2n).
3) Every ovule has a protective outer layers of
cells named the integuments.
15. 4) The embryo sac mother cell (2n) goes
through meiosis to form megaspores
(n) which is a row of four haploid
cells.
5) The four megaspores are linearly
arranged.
6) Usually one becomes funtional and
develops further.
16. 7) Three of four megaspores will
degenerate, leaving one in the ovule.
8) The remaining one haploid cell
develops to form the young embryo
sac.
9) The megaspore will grow and
enlarges, filling up most of the ovule.
17. 10) The megaspore divides mitotically 3
times to form 8 nucleatic gametocytes
and embryo sac, 8 nuclei within the
cytoplasm of a single cell have no cell
walls.
11) Antipodal cells are produced after the
migration of the 8 nuclei to one end of
the cell.
20. During the growth of the pollen
tube, the generative nucleus which
follows closely behind the tube nucleus
divides by mitosis to produce two male
gamete nuclei.
Pollen tube grows down the style into the
stigma and towards the ovule.
22. Double fertilisation means a
process where a diploid zygote and
triploid nucleus are formed.
In the embryo sac, one male
gamete nucleus fuses with the egg cell
forming a diploid zygote (2n) .
The other male gamete nucleus fuses
with the two polar nuclei forming a
triploid (3n) .
23. Thus, in an embryo sac,2 fusions take
place simultaneously.
After fertilisation, the diploid zygote
divides by mitosis forming the
embryo.
The triploid zygote also undergoes
repeated mitotic division to form the
endosperm which becomes the edible
part of the fruit.
24. Upon reaching the micropyle, the tube
nucleus disintegrates.
Besides, the tip of the tube bursts
open, the male nuclei then enter the
embryo sac.
Double fertilisation is unique to
angiosperms which occur in the ovule.
25. The division of triploid nucleus is very
important to give rise to the
endosperm that nourishes the embryo
and growing seedling.
It also helps to form the food
storing tissue of the seed.
The synergid cells and the antipodal
cells degenerate.
31. Ensures the genetic information
of the parent plants is passed
down to the next generation.
Existing variation among the next
generation.
Ensures the survival of the species.
32. For protection of the seed and aids in
the dispersal of the seeds.
Ensures the survival of flowering
plants in changing environment.
Ensures the successful germination of
a seed into a new plant.
Ensures the continuity of the plant
species.
33. Growth in Multicellular
Organisms
Growth:
Is a permanent process
(irreversible) with an increase in the
body mass, size and number of cells.
Involves quantitative changes in solid
matter, dry mass and the amount of
cytoplasm.
34. Development:
The changes in shape, function and
complexity associated with growth.
Involves qualitative changes
that are related to differentiation
and specialisation to perform specific
functions.
35. Cell division stage:
The number of cells of an
organism rises by mitosis.
One cell divides by mitosis in
geometric progression. For example :
1 2 4 8 16 cells, and so on.
36. Cell enlargement stage:
Also known as cell elongation.
Vacuolation is important in cell
enlargement of plants.
The volume and size of cells increase
through the intake of water and other
substances from the environment by
osmosis and diffusion.
37. Cell differentiation stage:
Cells growth begins to differ from each
other to form specialised and
permanent cells with specific
functions.
For instance, the neurones and
specific types of blood cells in
animals, the xylem and phloem cells in
plants.
38. The process
of Growth
Involves elongation and branching
of roots and shoots.
Brought about by apical meristems.
Importance :- produces xylem and
phloem .
39. Cells of the primary meristem continue to
divide, thereby elongating the root.
Cells of the primary meristem stop
dividing and cease to be meristematic.
Cells elongate and expand
through absorbing nutrients and water
through osmosis.
Cells differentiate into particular tissue
types which is also called zone of
maturation.
40. Nucleus
Small vacuoles
Cytoplasm
Vacuoles
enlarging
Small vacuoles fuse to form a
large central vacuole
Cytoplasm and nucleus push towards the cell margin
42. Thanks to:
Pn Prema a/p Kuttam Pillai (GPM
SMK Aminuddin Baki, Chemor)
Liew Bih Ling (Thinkquest Manager)
Gan Wan Yeat, Exploring, Penerbitan Fajar
Bakti Sdn. Bhd, Shah Alam, 2006.