Successful reproduction aims to produce a new living organism, which (at some stage) will
become independent of the parent(s).
Sexual reproduction involves two parents as the new offspring is formed from a
combination of their genetic material.
Asexual reproduction involves only one parent, and the offspring is an identical copy of the
parent.
Sexual reproduction in plants
Sexual reproduction in plants, like animals, involves the production of gametes. In plants the
male gamete is contained in the pollen grain, and the female gamete is the egg which is
contained in the ovule.
Structure of a flower
S tigm a
S tam en
{
A nther
Filam ent
N ectary
S epal
Petal
S tyle
O vary
O vule
Egg
Structure
Sepal
Function
Protects the bud
Petal
Surrounds reproductive organs and can
attract insects
Stamen
Male part of flower
Anther
Pollen grain produced here
Stigma
Catches pollen grains
Ovary
Contains the ovules
Nectary
(insect pollinated only)
Produces nectar which attracts insects
Pollination
 The transfer of pollen from the anther to the stigma is called pollination.
 Pollination is carried out by insects or wind.
The structure of a flower is altered depending on the plant’s method of pollination:
Structure
Insect pollinated flowers
Wind pollinated flowers
Petals
Brightly coloured and
scented
Dull petals
Pollen
Sticky or spiky to stick to
insects
Very light to be carried in the wind
Stigmas
Sticky to enable pollen to
stick to it
Hangs outside the flower.
Feathery (creating a large
surface area). Both of
these help to catch pollen
Stamen
Inside flower so that insect
brushes past
Large and hanging out of flower so
that pollen blown by wind
Nectar
Sweet and sticky to attract
insects
None as do not need to attract
insects
 The pollen grain contains the male sex cell.
 The female sex cell (egg) is in the ovule, which is in the ovary.
 To produce a new plant the male and female sex cells (gametes) must fuse. This fusion of the
gametes is called fertilisation.
Fertilisation occurs as follows:
1. the pollen grain containing the male gamete lands on the stigma
2. a pollen tube develops and grows down through the style towards the ovule.
3. the male gamete moves down the pollen tube and enters the ovule
4. fertilisation occurs when the male gamete fuses with the female gamete (egg).
Fruit formation
Once fertilisation has taken place the ovule becomes a seed and the ovary becomes a fruit.
 The ovary wall often becomes soft and fleshy as in tomatoes and grapes.
 Sometimes it becomes hard and dry e.g. pods (beans) or nuts (hazel).
The seed has four main parts:

Seed coat

Food stores

Embryo root

Embryo shoot
Seed Coat
Embryo Shoot
Embryo root
Food Stores
Seed dispersal
The seeds must be scattered as far as possible from the parent plant to reduce competition for food,
light and water.
Dispersal
Mechanism
Description
Examples
Sycamore
Wind
Extensions which act like parachutes or
wings to carry the seed in the wind
Poppy
Wind
Fruits may be shaken by wind to release
seeds like pepper
Examples
Dispersal
Mechanism
Description
Cherry
Animal
(internal)
Brightly coloured, juicy, edible layer
entices animals to eat it. Seeds pass
through the digestive system unharmed
and are passed out in the faeces away
from the parent plant
Burdock
Animal
(external)
Have hooks which stick to animals fur
then fall off away from parent plant
Acorn
Animal
(external)
May be carried away by animal and
dropped
Summary of sexual reproduction and life cycle in plants:
Asexual reproduction in plants
Vegetative propagation means growing plants from plant parts rather than from seed, and
so only requires one parent.
o Bulbs and tubers are used to produce new plants vegetatively

Bulbs are made up of separate leaves like an onion or daffodil

Tubers are solid with eyes, like potatoes

Both are stores of food (storage organs)
o Some plants have attached offspring:

Runners – a long stem with a new plant at the end.

Special stems grow out from the parent plant and when they
touch the soul roots begin to grow.

Plantlets – tiny plants attached to the parent plant


Plantlets detach from the parent and grow separately.
Offsets – plants grow up from the roots of an adult
Sexual reproduction in animals
A new organism produced by sexual reproduction is formed
from genetic information from both parents.
Each parent's genetic information is contained in a gamete (sex cell).
The female gamete is called an _________ (or __________),
The male gamete is called a ___________.
Sexual reproduction is successful at the point of fertilisation.
Fertilisation is the moment when the nucleus from the male gamete fuses with the nucleus
from the female gamete.
Internal fertilisation takes place inside the body of the female. The sperm is deposited in the
female's body by the male. External fertilisation takes place outside of the bodies of the
parents. The female lays the eggs and the male deposits the sperm on (or close to) the eggs.
Asexual reproduction in animals
Asexual reproduction in animals can take place by:

Budding

Parthenogenesis

Regeneration

Binary fission
Sexual reproduction versus asexual reproduction
Sexual Reproduction
Advantages
Produces variation
within a species
Disadvantages
Requires more
energy (displays,
gamete production
etc)
Slower than asexual
reproduction.
Asexual Reproduction
Advantages
Quicker than sexual
reproduction.
Lower energy cost
Disadvantages
No genetic variation
(unfavourable
characteristics
passed on to
offspring)