Sexual reproduction and its importance for survival of species
Sexual reproduction is important for the survival of a species and increases
variation. Therefore it is sexual reproduction that produces variety in a species
and maintains biodiversity.
Variation
The differences between organisms are called variation. Variation can occur
within a species.
There are two different types of variation.
1. Continuous variation – When every member of a species shows a
characteristic but that characteristic varies from one extreme to another.
e.g. Height in humans, tail length in mice, volume of milk produced by cows
2. Discontinuous variation – When organisms either have or don’t have a certain
characteristic and can be divided into different groups.
e.g. Ability to roll tongue in humans, Flower colour in sweet pea plants, blood
group in humans
Inherited characteristics

Certain characteristics that an organism possesses are determined by
genetic information that they received from their parents.

The parent’s genetic information is contained within their chromosomes,
which are found in the nucleus.

Every normal body cell contains a nucleus with two matching sets of
chromosomes

Genetic information is passed from parents to their offspring by sex cells in
the process of fertilisation
Sex cells
Sex cells are known as gamete
Male
Female
Gametes
Name of male
gamete
Site of male
gamete production
Plant
Pollen
Animal
Sperm
Anther
Testes
Name of female
gamete
Site of female
gamete production
Ovule
Ovule
Ovary
Ovary
Gametes are formed from a gamete mother cell with two set of chromosomes
(diploid).
Gametes only possess one set of chromosomes (Haploid).