Biodiversity of plants and reproduction in plants
Reproduction in plants
Asexual and sexual reproduction
Plants reproduce when they make spores and when male gametes and a female gamete
join.
2 different kinds of reproduction
® Asexual reproduction
® Sexual reproduction
Asexual reproduction
This is the reproduction without using male and female gametes.
Example
A moss sends up a sporangium and spores are produced, there is no male or female parts
joining just a process of splitting. There is no introduction of new genetic material
When part of a living organism is used to make a new individual that is the same as the
original organism. Reproduction happens quickly and is an advantage for survival of the
species.
In flowering plants there is a second kind of sexual reproduction called vegetative
reproduction which is when a part of a plant body is used to make a new plant.
Advantage of asexual reproduction
® If the Individual plant is well adapted to an environment all offspring will be equally well
suited to it.
® Crops can easily and quickly grow using vegetative propagation.
Disadvantage of asexual reproduction
® Offspring are identical to the plant so all will suffer unfavourable conditions
Sexual Reproduction
Involves the fusion of special sex cells called gametes. The offspring are unique
individuals that may resemble the parents but are not exactly the same as either of them.
Sexual reproduction takes a longer period of time before the offspring are produced. Many
offspring are produced during sexual reproduction.
, Advantages of sexual reproduction:
® More variation among the individuals produced. So, offspring may be better adapted to
new environmental conditions.
® Individuals in an area are genetically slightly different so they are less likely to be
affected by diseases.
® Many individuals can be produced
Disadvantages of sexual reproduction:
® Slower process than asexual reproduction, not suitable for crop farming.
® More variation in the offspring so some are inferior
® Takes a longer time to become adult
® Mosses and ferns, sexual reproduction only happens if there is water on the plants
Flowers as reproductive structures
What is a flower?
The angiosperms or flowering plants are the most successful plant groups om earth.
More than 250 000 species that have adapted in a number of ways to suit living in all
different kinds of habitats
Flowers are successful on land because:
® Don’t need water for fertilisation
® Developing embryo is not exposed to the air and is well protected inside the ovary
® Produce seeds
The flower is the reproductive organ where sexual reproduction takes place.
During sexual reproduction 2 haploid (n) cells called gametes fuse during fertilisation
(mitosis) to form a diploid (2n) zygote which develops into an embryo.
Some flowering plants have both male and female parts in the same flower and these
flowers are called a hermaphrodites. Some flowers are unisexual and may be either male
or female.
The structure of the flower
Flowers are temporary plant parts and can be produced in large numbers.
Flowers have a stalk with 4 regions called whorls:
1. Outermost whorl is made up of sepals which are collectively called calyx.
Function: green and protect the flower when its in the bud
2. Second whorl is made from petals which are collectively called corolla.
Function: often brightly coloured and attract insects and birds. If a plant has petals
and sepals that look the same are called tepals
3. The stamens which is the male part of the flower which forms the third whorl.
Reproduction in plants
Asexual and sexual reproduction
Plants reproduce when they make spores and when male gametes and a female gamete
join.
2 different kinds of reproduction
® Asexual reproduction
® Sexual reproduction
Asexual reproduction
This is the reproduction without using male and female gametes.
Example
A moss sends up a sporangium and spores are produced, there is no male or female parts
joining just a process of splitting. There is no introduction of new genetic material
When part of a living organism is used to make a new individual that is the same as the
original organism. Reproduction happens quickly and is an advantage for survival of the
species.
In flowering plants there is a second kind of sexual reproduction called vegetative
reproduction which is when a part of a plant body is used to make a new plant.
Advantage of asexual reproduction
® If the Individual plant is well adapted to an environment all offspring will be equally well
suited to it.
® Crops can easily and quickly grow using vegetative propagation.
Disadvantage of asexual reproduction
® Offspring are identical to the plant so all will suffer unfavourable conditions
Sexual Reproduction
Involves the fusion of special sex cells called gametes. The offspring are unique
individuals that may resemble the parents but are not exactly the same as either of them.
Sexual reproduction takes a longer period of time before the offspring are produced. Many
offspring are produced during sexual reproduction.
, Advantages of sexual reproduction:
® More variation among the individuals produced. So, offspring may be better adapted to
new environmental conditions.
® Individuals in an area are genetically slightly different so they are less likely to be
affected by diseases.
® Many individuals can be produced
Disadvantages of sexual reproduction:
® Slower process than asexual reproduction, not suitable for crop farming.
® More variation in the offspring so some are inferior
® Takes a longer time to become adult
® Mosses and ferns, sexual reproduction only happens if there is water on the plants
Flowers as reproductive structures
What is a flower?
The angiosperms or flowering plants are the most successful plant groups om earth.
More than 250 000 species that have adapted in a number of ways to suit living in all
different kinds of habitats
Flowers are successful on land because:
® Don’t need water for fertilisation
® Developing embryo is not exposed to the air and is well protected inside the ovary
® Produce seeds
The flower is the reproductive organ where sexual reproduction takes place.
During sexual reproduction 2 haploid (n) cells called gametes fuse during fertilisation
(mitosis) to form a diploid (2n) zygote which develops into an embryo.
Some flowering plants have both male and female parts in the same flower and these
flowers are called a hermaphrodites. Some flowers are unisexual and may be either male
or female.
The structure of the flower
Flowers are temporary plant parts and can be produced in large numbers.
Flowers have a stalk with 4 regions called whorls:
1. Outermost whorl is made up of sepals which are collectively called calyx.
Function: green and protect the flower when its in the bud
2. Second whorl is made from petals which are collectively called corolla.
Function: often brightly coloured and attract insects and birds. If a plant has petals
and sepals that look the same are called tepals
3. The stamens which is the male part of the flower which forms the third whorl.
