Reproduction in plants and
animals
plant reproductive system
• reproduction is the process of producing new off springs
from the existing generation.
• It allows species not to get extinct and continue life.
• Sexual and asexual reproduction are the two types of
reproduction.
• Asexual reproduction is the process of producing
genetically identical off springs by one parent. No
gametes are involved in this type of reproduction.
• Most plants undergo asexual reproduction and asexual
reproduction in bacteria is known as binary fission which
produces daughter cells.
• Advantages of asexual reproduction- can increase
population with required conditions.
Can spread in a suitable environment quickly
take less time and efficient to complete the whole process
• disadvantages of sexual reproduction- changes in the
environment affect population.
Limited genetic variation
diseases are likely to spread more quickly.
• sexual reproduction is a process involving fusion of
males and female gamete from two parents producing a
genetically non identical off spring.
• Gametes are sex cells
• haploid cells are cells that contains half the number of
chromosomes.(gamete cells with 23 chromosomes)
• Diploid cells are cells that contain full number of
chromosomes(body cells with 46 chromosomes)
• half the number of chromosomes in gametes ensures that
the number of chromosomes remain constant through out
generations.
• Advantages of sexual reproduction- genetic variation
environmental changes does not affect
diseases are less likely to affect the whole population
• disadvantages of sexual reproduction- slow and
inefficient process
hard to rise population
limited off springs produce
• asexual reproduction in plants
1. natural(runners)- some plants grow side
branches known as runners which have a
planlet at its end. These grow roots to the soil
and turn into an individual clone of the parent
plant.
2. artificial(cuttings)- good parent plant is
selected. A branch, root or leaf is cut. Then it
is dipped in rooting powder containing the
rooting hormone. The roots grow. This is
placed in soil with enough water and required
nutrients. This grows in to an individual clone.
This is fast and cost effective method for
planters and it is much cheaper.
• Sexual reproduction in the plant occurs In the flower.
• Pollen-male gamete
• ovule-female gamete
• transferring of pollen from anther to the stigma is known
as pollination
• structures of the flower:
1. sepal- protects flower before blooming
2. petals- colorful in insect pollinated plants to
attract insects.
3. Anther- produces and holds pollen
4. stigma- top part of the female part which
collects the pollen.
5. Ovary- produces ovum
6. ovule- contain female sex cells in the plant
• there are 2 types of pollination
1. self pollination- transferring of a pollen to the
stigma of the same plant. Decreases genetic
variation as the gametes from male and female of
same plant is used.
2. Cross pollination- transferring of a pollen to the
stigma of another plant of the same species.
Increases genetic variation.
• There are two types of flowers
1. insect pollinated flowers- contains large and
colorful petals to attract insects. Contains scent
and nectar too. Pollen grains are produced in
moderate amounts, they are large and sticky to
easily attach to insects. Anther is located in the
inside of the flower to brush against the pollen
grains on the insects. The stigma is also located
inside to brush against insects and collect the
pollen.
2. Wind pollinated flowers- small and non colorful
flowers. Contains no scent and nectar. Pollen
grains are produced in large amounts to drift
away in the wind. They are small and very
lightweight to be easily blown away by wind.
The anther is located outside the flower to blow
away pollen grains in large amounts. The stigma
is also located outside the flower to catch pollen
grain drifting through the wind. This is branched
or can be very feathery.
• Fertilization in plants- the fusion of male and female
gamete in plants happen in the ovule of the flower.
• Pollen tube- after the pollen is placed on the stigma. It
germinates and grows a pollen tube. The pollen tube
grows down the stigma, style and the through the wall of
the ovary into the ovule through a tiny opening on
surface of ovule known as the micro pyle. Then the male
nucleus reaches the ovule through the pollen tube and
fuse together resulting in a zygote to form. After the
fertilization the ovule containing the zygote becomes the
seed. Ovule wall becomes the seed coat or the testes and
ovary wall becomes the fruit.
• Germination is the process of the start of the growth of
the seed. The seed contains a structure known as the cotty
ledon which act as the storage component providing the
nutrients till the plant grows and can carry out
photosynthesis by itself.
• Factors required for germination- water which is
absorbed by seed coat and split which lets the radical and
plumule out of the seed. Oxygen require for aerobic
respiration and optimum temperature is needed for the
enzymes work.
reproductive system in human
• sexual maturity of males and females known as
adolescence or puberty.
• Secondary sexual characteristics are characteristics theat
appear in both males and females from puberty.
• Males- age between 13 to 16
shoulders widen
larynx enlarge and voice deepens
growth of muscles and bones accelerates
pubertal hair grows
sperm production begins
penis becomes larger
• females- age between 10 and 14
pubic area widen
pubertal hair grows
storage of more fats and body mass increase
mammary glands starts to grow
growth of bones and muscles accelerates
release of egg cells
menstrual cycle starts
