1. Reproduction in Plants
define asexual reproduction as the process resulting in the production of genetically identical offspring from one parent.
define sexual reproduction as the process involving the fusion of nuclei to form a zygote and the production of genetically dissimilar offspring.
state the functions of the sepals, petals, anthers and carpels.
outline the process of pollination.
describe the growth of the pollen tube and its entry into the ovule followed by fertilisation.

2. Sexual VS Asexual Reproduction
Sexual reproduction: process involving the fusion of nuclei to form a zygote and the production of genetically dissimilar offspring
Asexual reproduction: process resulting in the production of genetically identical offspring from one parent
Involves fusion of two gametes
Does not involve fusion of gametes
Requires two parents
Require only 1 parent
Variation in offspring
Offspring are identical

3. Asexual reproduction Advantages:
Offspring produced are identical to parents, hence higher chance of good characteristics of parents being passed to the offspring
Only one parent is involved, hence do not depend on external agents, like wind or insect and able to reproduce rapidly
Disadvantage:
No genetic variations among offspring, hence less adapted to changes in the environment

4. Parts of a Flower stigma Petal style carpel ovary anther ovule stamen
filament
Sepal
Receptacle
Pedicel
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5. Parts of a flower Structure Function Sepals
Protect the other parts of the flower in the bud stage
Receptacle
enlarged end of the flower stalk
Pedicel
Flower stalk
Petals
are brightly coloured to attract insects for pollination
provide a platform for insects to land

6. Parts of a Stamen vascular bundle pollen sacs pollen tube nucleus
pollen grains
Stamen
anther lobes
generative nucleus
Stamen with upper half of anther cut off
Side view of a stamen
Mature pollen grain
Pollen grains
Filament
Anther
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7. Stamen Structure Function Stamen consists of an anther and a filament
holds the anther in a suitable position to disperse the pollen
Anthers
produces pollen grains.
When it matures, it splits open to release the pollen grains.
Pollen grain
contain the male gametes

8. Parts of a Carpel stigma Carpel The female part of a flower. All
the carpels together make up the pistil.
. A carpel consists of:
- an ovary;
a style above the ovary; and
one or more stigmas.
style
ovary
Side view of a carpel
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9. Carpel Structure Function Stigma It receives the pollen grains.
The mature stigma secretes a sugary fluid that stimulates the pollen grains to germinate
Style
connects the stigma to the ovary
Ovary
contains one or more ovules

10. Pollination
Pollination is the transfer of pollen grains from the anther to the stigma.
Pollination is usually brought about by insects or wind.
There are two types of pollination:
a) Self-pollination
b) Cross-pollination
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11. Self-Pollination
Self-pollination: Pollen grains are transferred to the stigma of the same flower, or a different flower of the same plant.
Features of plants that self-pollinate
Bisexual flowers with anthers and stigma maturing at the same time.
Stigma is found directly below the anthers.
Plants with closed bisexual flowers
transfer of pollen grains
anther
stigma
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12. Self-pollination Advantages Only one parent plant is required
Beneficial qualities are passed down from parent plants to offspring because offspring inherit the parents’ genes
Not dependent on external factors to pollinate
Less pollen is wasted
Disadvantages
Less varieties of offspring produced since they are genetically similar to the parents.
Hence, reduces the chance of the species surviving changes in the environment
may lead to the offspring becoming weaker, smaller and less resistant to diseases.

13. Cross-Pollination
Cross-pollination: Pollen grains are transferred to a flower in another plant of the same kind of species.
Features of cross-pollinated plants:
Have either male or female flowers.
Anthers and stigmas of bisexual flowers mature at different times.
Stigma of bisexual flowers may be located some distance away from the anthers .
Plant A
anther
transfer of pollen grains
stigma
Plant B

14. Cross-pollination Advantages
Offspring can inherit beneficial qualities from both parents.
More varieties of offspring are produced.
This increases the chances of the offspring surviving changes in the environment.
More viable seeds that are capable of surviving longer before germination are produced.
Disadvantages
Require two parent plants
Require external factors, like insects or wind
More pollen is wasted

15. Insect pollinated plants
Features
Reasons
Large petals
To provide a landing platform for insects to rest
Brightly-coloured; fragrant; presence of nectar
To attract the insects
Nectar guides
To lead insects to the nectar
Pollen grains with rough surface
To cling on insects’ bodies
Stigmas are sticky
To be able to retain pollen grains settling on them from insects

16. Wind pollinated plants
Features
Reasons
Protruding, large, feathery stigma
To provide a large surface area to capture windborne pollen grains
Long filament with protruding anthers
To allow pollen grain to be carried away by wind
Pollen grains are light and smooth
To be carried away easily by the wind

17. Comparisons between insect-pollinated and wind-pollinated flowers
Feature
Insect-pollinated flowers
Wind-pollinated flowers
Petals
large with brightly-coloured petals
small and dull-coloured, without petals
Nectar
Present.
Absent.
Scent
Fragrant and sweet-smelling
Scent is absent.
Stigmas
small and compact and do not protrude out of flowers
Protruding, large and feathery
Stamens
Not pendulous and do not protrude out of flower
Long and pendulous filaments with protruding anthers
Pollen
Fairly abundant. Pollen grains are larger with rough surfaces.
More abundant. Pollen grains are tiny with smooth surfaces.
Nectar guides
Absent
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18. Fertilisation
One male gamete fuses with the ovum to form a zygote. The other male gamete fuses with the definitive nucleus to form an endosperm nucleus.

19. Fertilisation
When a pollen grain germinates on the stigma, a pollen tube grows out of it.
The pollen tube grows right through the style into the ovary.
The pollen tube enters the ovule through an opening in the ovule wall called the micropyle.
The tip of the pollen tube bursts, releasing the two male gametes into the ovule.
One male gamete fuses with the ovum (female gamete) to form a diploid zygote.
The other male gamete fuses with the definitive nucleus to form the endosperm nucleus.
germinating pollen grain
style
stigma
pollen tube
ovary wall
definitive nucleus
male gametes
ovule
ovum (egg)
micropyle
funicle
placenta

20. - Pollen grain settles on stigma and stigma secretes sugary fluid.
- Pollen grains germinates.
- Pollen grain produces a pollen tube.
- Pollen tube grows through the style, into the ovary.
- Pollen tube enters the ovule and releases two male gametes
- One male gamete fuses with the ovum to form a zygote.
- The other male gamete fuses with the definitive nucleus to form the endosperm nucleus

21. What happens after fertilisation?
The ovule develops into the seed
The ovary develops into the fruit
The zygote develops into the embryo
When the seed germinates, embryo develop in the new plant