Asexual reproduction produces genetically identical offspring through mitosis without the fusion of gametes. It occurs through vegetative reproduction where a new plant grows from a part of the parent plant, such as through budding, root offshoots, stem cutting. The offspring are clones that resemble the parent plant completely and allow desirable traits to be passed on rapidly without fertilization or dispersal mechanisms.

1. The production of new individuals that
does not involve fertilisation.
no fusion of 2 reproductive cells (gametes)
produces identical offspring
because mitosis usually occurs during
asexual reproduction
examples:
budding
spore formation
vegetative reproduction
Asexual Reproduction

2. Mitosis:
A cell divides to produce 2 daughter cells, each
having the same number of chromosomes as
the parent cell.
The daughter cells have the same genes as the
parent cell
The offspring produced asexually are
genetically identical to the parents and are
called clones

3. Sexual reproduction
reproduction that involves
fusion of 2 gametes

4. Natural vegetative propagation in
flowering plants.
involves the growth of a new part of a plant
(bud/stem), which eventually becomes
separated from the parent plant to form a new
individual
many flowering plants produce vegetatively by
means of underground storage organs such
as rhizomes, bulbs,corms,tuburs,runners
the food stored enables the plant to survive
through unfavourable climatic conditions. When
favourable conditions return, the buds use up
the stored food and develop rapidly into new
plants (perennation)

5. Advantages
process does not need external agents eg
insects and wind - for pollination and dispersal
since food is usually present in the vegetative
structures, buds can develop rapidly into
daughter plants
the daughter plants resemble the parent plant
completely - desirable qualities in the parent
plant are passed on to the young plants
process involves only one parent, and no
fertilisation is required
since plants are already in a suitable habitat,
they can colonise the area more rapidly

6. Disadvantages
lack of any dispersal mechanism may
lead to overcrowding, causing the new
plants to compete for food and light
the new plants are less varied compared
to those produced by seeds - may be less
adaptable to changes in environmental
conditions

7. Artifical methods of vegetative
reproductionCutting
stems of certain plants are cut just below a node
the cutting is planted in suitable soil so the node can
develop adventitious roots form a new plant
Eg: sugarcane, tapioca, oleander
layering:
a low branch with a node is bent down and a ring of
bark is removed from the node.
the ringed section is completely covered with moist
soil while the end of the branch is allowed to remain
free
when roots have developed, the branch is cut off from
the parent plant and allowed to grow on its own
eg: lime, bougainvillea

8. Marcotting
Artificial method of vegetative Reproduction
Layering

9. Marcotting
a ring of bark is removed from a branch
then, a layer of moist soil is wrapped round the ringed
portion of the branch and kept in place
the soil is kept moist by watering every day
when roots appear, the branch is cut and planted.
eg: rambutan, durian, chiku trees
Grafting & budding
a healthy plant with an established root system is selected
- stock
a portion of the plant to be propagated (scion) is carefully
cut off
it is attached to the stock, and the two grow together
the stock absorbs water and dissolved mineral salts
through its roots and transports them to the growing
scion
eg: roses, cherry, almond

10. Budding
a bud, together with some cambium, is taken from a
selected plant – scion a T-shaped cut is made in the bark
down to the cambium in the stock the scion is carefully
inserted but with the bud still exposed beneath the bark
of the stock
the thin cambium in the scion is now in contact with the
cambium of the stock the scion and stock are tied
together and the junction protected with wax the tissues
of the two plants soon unite and the bud grows into a
shoot
eg: lemon, hibiscus
Grafting
a twig bearing several buds is cut off
its lower V-shaped end is inserted into a complementary
shaped end of the stock
The two are tied as in budding and the buds will
develop into shoot

12. Sexual reproduction in flowering plants
General parts of a flower

13. Pedicel
a flower stalk
flowers with no pedicels: sessile flowers
Receptacle
the enlarged end of the flower stalk on which the other
parts of the flower are borne
Sepals
modified leaves which enclose and protect the other parts
of the flower in the bud stage
all the sepals together make up the calyx
usually form the outermost whorl of floral leaves but some
flowers (eg hibiscus) have another whorl of floral leaves
outside the sepals which make up the epicalyx of the
flower
General parts of a flower

14. Petals
modified leaves forming the
conspicuous part of the flower
usually brightly coloured in insect-
pollinated flowers form
the corolla of the flower functions
brightly coloured to attract insects
for pollination provide a landing
platform for insects

15. Stamens (andromecium)
collective name for the stamens of a flower which
produce pollen grains
the male part of the flower
consists of a filament bearing an anther
anther: usually made up of 2 lobes, each
containing 2 pollen sacs --> inside are pollen
grains
pollen grains are produced by meiosis and so
contain 2 haploid male gametes which are the
reproductive nuclei of the flower
when the anther matures, its 2 lobes split, setting free
the pollen grains

16. Pistil (gynoecium)
the female part of the flower
consists of one or more units called carpels
consists of an ovary, a style, and one or
more stigmas
stigma: a swollen structure at the end of the
style which receives the pollen grains
ovary: contains one or more ovules
within each mature ovule is a female
gamete called the ovum
the region in the ovary to which the
ovules are attached is called the placenta
ovule is attached to the placenta by
a funicle

17. Pollination
the transfer of pollen grains from the anther to the stigma
self-pollination: if pollen grains are transferred to the stigma of
the same flower or a different flower in the same plant
cross-pollination: if pollen grains are transferred to a flower in
another plant of the same kind

18. Advantages
offspring produced may have valuable
qualities from both parents
abundant and more viable seeds tend to be
produced
more varieties of offspring can be produced
(greater genetic variability) --> increases the
chance of survival of the species during
changes in the environment
As genetic variability is important for the
survival of a species, most types of plants
possess special devices favouring cross-
pollination

19. Fertilisation and post-fertilisation changes

20.  After pollination, the pollen grain germinates in response
to the sugary fluid secreted by the mature stigma.
From each pollen grain, a pollen tube grows out.
The cytoplasm and the 2 nuclei (vegetative and generative
nuclei) pass into the pollen tube.
The growth of the pollen tube is controlled by
the vegetative nucleus.
Enzymes are secreted to digest the tissues of the stigma
and style as the tube grows
Thus, the pollen tube penetrates right through the style as
it grows and enters the ovule usually through
the micropyle (an opening in the ovule wall)

21. along the way, the generative nucleus divides to
form 2 male, non-motile gametes.
The vegetative nucleus soon disintegrates
within the ovule, the tip of the pollen tube absorbs
sap and bursts, releasing the 2 male gametes. One
male gamete fuses with the ovum to form
the zygote - fertilisation
The other male gamete fuses with the definitive
nucleus (secondary nucleus) to
form endospermnucleus
The zygote develops into the embryo of the seed
with cotyledons, developing shoot (plumule) and
developing root (radicle)
The endosperm nucleus divides and gives rise to
the endosperm

22. In some seeds, the endosperm is completely
absorbed by the embryo which stores the food
materials in the cotyledons
Non-endospermic
A fruit is generally formed from the ovary and the
ovules
The ovary wall ripens to form the fruit wall
(pericarp)
the ovules become the seeds
The funicle or seed stalk is attached to the part of
the fruit called the placenta
A fruit has one or more fruit chambers
called loculi
in some fruits, the pericarp becomes hard and dry;

24. Dispersal of fruits and seeds
Dispersal is necessary to:
avoid overcrowding and competition for
food and light with the parent plants enable
plants to colonise new and favourable
habitats reduce spread of diseases

25. Dispersal by
1. Animals
succulent pericarp, scented and brightly
coloured skins to attract animals
the whole fruit may be eaten by animals. The
seeds may be small and hard, indigestible,
and are removed in the faeces, away from the
parent plant
some fruits have hook-like structures by
which they can adhere onto the fur or skin of
animals passing by. These fruits may later be
brushed off the animals' bodies or fall off
when the hooks shrivel. eg: urena, xanthium

26. Wind
small and light fruits and
seeds so they can float in
the air and be readily
blown by the wind
large, flattened wing-like
structures or a parachute
of fine-hair to
provide enlarged surface
area to increase air
resistance or buoyancy in
air. eg: angsana fruit,
tridex fruit, kapur fruit,
tecoma, shorea, cotton

28. 3. water
adapted for floating and can drift for considerable distances
eg coconut has waterproof skin and fibrous husk containing
numerous air spaces which lighten the fruit
the seed within it contains a store of food and there is
sufficient water in the seed to enable its germination even
on sandy shores
eg. the seeds of water lily have an aril (small float) which
holds air. The seeds can float on the water away from the
parent plants until the arils decay. Then, they sink to the
bottom of the river/pond and germinate.
4. explosive mechanism
these fruits, on drying up, burst open suddenly with great
force to throw out the seeds
eg. when ripe balsam fruits dry up, they burst open and
eject the seeds away from the parent plant
eg. rubber fruits, legumes of many plants (peas, beans etc)

29. MCQ
1. Which structure is not essential in a wind-pollinated
flower?
a. anther
b. ovary
c. petal
d. stigma
2. Which statement is true of asexual reproduction in
plants?
a. insects are needed to transfer pollen
b. new plants grow from seeds
c. offspring are genetically identical to their parents
d. two types of gamete are involved

30. 3. Many wind-pollinated flowers have
a. feathery stigmas and light pollen
b. feathery stigmas and sticky pollen
c. short stigmas and light pollen
d. short stigmas and sticky pollen
4. Which statement is not true of the offspring resulting
from asexual reproduction?
a. they are produced by self-fertilisation
b. they are produced from a single parent
c. their cells have the same alleles
d. their cells have the same number of chromosomes

31. 5. Which features correctly describe a wind-
pollinated
flower?