Reprodution is the formation of new
individuals,it is one of the characteristics of life.
Plants carry out both asexual and sexual
reproduction. The flower is a structure in which
plants sexua reproduction occurs. The stages in
plant sexual reproduction are: Pollination,
Fertilisation, Dispersal and Germination.
There are two types of reproduction when it
comes to plants, there is 1)Asexual
Reproduction 2)Sexual Reproduction
1)Asexual Reproduction
Asexual Reproduction only
involves one parent
Fertilisation is not part of the process
of asexual reproduction.
In asexual reproduction the offspring
are identical to the parent.
EX-Strawberry plants are examples of Runners
Runners-A method of asexual reproduction in plants.
How it works:
2)Sexual Reproduction
Sexual Reproduction involves two parents
Gamete-A sex cell
Fertilisation is part of the sexual reproduction process
The offspring of sexual reproduction are
not identical to their parents but have a mix
of similar characteristics from each.
The flower contains structures needed for sexual reproduction
They are:
Their are five stages of Plant Reproduction
1)Pollination 2)Fertilisation 3)Seed and fruit
formation 4)Dispersal 5)Germination
1)Pollination
The transfer
of pollen from
the stamen to
the carpel
There are two types of pollination methods:
Wind Pollination
In wind pollination the carpel and stamen are usually located
outside the plant so the wind that can carry its pollen can also
blow the pollen of other plants onto the carpel starting the
sexual reproduction process.
Plants of wind pollination tend not to be as colourful as
those of Insect pollination because in order to attract
insects, the petals of the flower must be coloured.
Insect Pollination
In insect pollination the Petals tend to be brighter to attract
insects to them, also the reason the flowers produce Nectar
is to lure the insects in so as they go for the nectar(sugar
water)the pollen on the stamen will rub off the insects coat
and stick, then when the insect leaves to go to another plant
the pollen off the past plant will fall off the coat and fall on
the carpel allowing the sexual reproduction process to
begin.
2)Fertilisation
The joining of the
Male and Female
gametes to form a
zygote.
Pollen carried from insects or the wind falls onto on the carpel
which results in the pollen(male gamete) forming a tube down in
the carpel to get to the ovary where the egg(female gamete) is
held, it will then form a zygote when the egg and pollen fuse together.
3)Seed and Fruit Formation
The Seed/Fruit Structure
Once Fertilisation is complete the ovule forms a seed. Each starts off as a Zygote surrounded by food
supply,the Zygote forms a tiny plant called an embryo.The embryo consists of a plumule and the
radical.The plumule will form the furture shoot of the plant and the radicle will form the future roots of
the plant.After fertilisation, the ovule swells with food causing a hard, tough shell called the Testa to
form around the ovule ,the testa forms the coat of the seed. If there are more than one ovules then the
fruit will contain many seeds eg-oranges.If not they will only contain a single seed,eg-Peaches.
4)Dispersal
Dispersal-The carrying of the seed
as far as possible from the parent
plant.
There are four types of dispersal:
Wind Dispersal
Seeds are dispersed by wind,they are often light and small.Some seed
that use this method of dispersal have small devices to carry them
longer distances.Eg-In the picture below.
Animal Dispersal
Animals can disperse seeds in two ways:They eat fruit that
contains seed and the seeds get digested and eventually
passed out later,or the fruit/seeds stick to the animals coat
and fall away later.
Self Dispersal
Involves seeds bursting out of their pod out of their own accord.In this
method they are flung away.
Water Dispersal
Some fruits are able to float carring the seeds inside of them,they
are able to be carried away in streams and rivers.
5)Germination
The growth of a seed
to form a new plant.
Conditions needed for germination
are:1)Water 2)Oxygen 3)A suitable
tempreture
The Main Events of Germination
1)Fruit from the seed allows the roots and shoot to grow.
2)The root grows down in the soil.
3)The shoot grows up into the air.
4)Once the shoot grows up it
starts to form leaves and starts
to make food for itself.
The Structure of the Plant
Petals-Protect the internal parts of the flower.Also the main
reason the plants are brightly coloured are because bright
colours attract insects for Insect pollination.
Sepals-The seplas protect the flower when it is a bud .(Before the flower blooms)
Carpel-Is the female part of the flower,each carpel produces an
egg cell(the nucleus of the egg is the female gamete),some flowers
have more than one carpel.
Stamen-The Stamen is the male part of the flower,The stamen produces
Pollen grains(the nucleus of the pollen grain is the male gamete),most
flowers have a large number of stamens.
The structure of the Carpel
Stigma-The stigma is the place the pollen grains will land.
Style-The style connects the stigma to the carpel ,in some plants the style is very short.
Ovary-The ovary contains one or more Ovules. Each Ovule produces an egg.The nucleus of the egg is the female gamete.
The Structure of the Stamen
Filament-The filament is a stalk that supports the
anther.It ensures that the anthers are located high
up in the flower, so that the pollen can leave the
flower more easily.
Anther-The anther makes pollen grains. The nucleus in each pollen is the male gamete.