1. IGCSE Biology – 4BI0
MAKING SENSE OF
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3. Copyright © 2015 Henry Exham
2.7 Reproduction in Humans – Sexual and Asexual
Objectives
3
• Can you describe the differences between sexual and
asexual reproduction?
• Do you understand that fertilisation involves the
fusion of a male and female gamete to produce a
zygote that undergoes cell division and develops into
an embryo?

4. Copyright © 2015 Henry Exham
2.7 Reproduction in Humans – Sexual and Asexual
Reproduction
4

5. Copyright © 2015 Henry Exham
2.7 Reproduction in Humans – Sexual and Asexual
Asexual Reproduction
5
• Cells in one part of the body divide by mitosis
and then break off from the parent to form a
new organism.
• All the offspring are genetically identical.
• These organisms all reproduce asexually.
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6. Copyright © 2015 Henry Exham
2.7 Reproduction in Humans – Sexual and Asexual
Sexual Reproduction
6
• Sex cells called gametes are produced.
• There are two types, a male gamete and
a female.
• The male gamete must move to the
female gamete and fuse.
• This is called fertilisation.
• The new cell formed is called a zygote.

7. Copyright © 2015 Henry Exham
2.7 Reproduction in Humans – Sexual and Asexual
Sexual Reproduction
7
• This cell will then divide many times by
mitosis to form the new organism.
Zygote
Embryo
Egg
Sperm

8. Copyright © 2015 Henry Exham
2.7 Reproduction in Humans – Sexual and Asexual
Sexual Reproduction - Gametes
8
• The male gamete sperm are produced in the
testes.
• In the female the ova are produced in the
ovaries.
• The cells inside these organs divide by meiosis.
• Meiosis produces cells that are not genetically
identical.

9. Copyright © 2015 Henry Exham
2.7 Reproduction in Humans – Sexual and Asexual
Sexual Reproduction - Meiosis
9
• In meiosis four cells are made from the original
cell.
• These cells are called haploid cells as they each
have half the compliment of chromosomes.
• This process is covered in more detail in section
5.2 along with mitosis.

10. Copyright © 2015 Henry Exham
2.7 Reproduction in Humans – Sexual and Asexual
Sexual Reproduction - Sperm
10
• Sperm cells have a tail for swimming.
• The head contains the genes from the father
in the nucleus.
• The acrosome digests its way into the egg for
fertilisation.

11. Copyright © 2015 Henry Exham
2.7 Reproduction in Humans – Sexual and Asexual
Cell Division
11
• The whole of asexual reproduction happens using mitosis.
• This is when a cell with the full number of chromosomes
(diploid) copies itself to become two identical cells.
• In sexual reproduction, the gametes are made using
meiosis.
• This produces haploid cells with only half the full number of
chromosomes.
• Once they combine to make a zygote they will once again be
up to the full number of chromosomes and the new cell can
continue dividing using mitosis.

12. Copyright © 2015 Henry Exham
2.7 Reproduction in Humans – Sexual and Asexual
Sexual and Asexual
12
Asexual Sexual
Produces genetically identical
organisms
Produces genetically different
organisms
Only needs one parent Needs two parents
Uses mitosis Uses meiosis to make gamete
and then mitosis to grow in size
after fertilisation
Very quick but no variation so
susceptible to disease
Slower but produces variation

13. This PowerPoint is protected under copyright.
It is designed for educational use. Either personal study or to be
presented to a class. It may be edited or duplicated for these
purposes only.
It must not be shared or distributed online in any format.
Some images used are under a separate creative commons license,
these are clearly marked.
Copyright © 2015 Henry Exham
Brought to you by MrExham.com
TERMS AND CONDITIONS
13