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AQA GCSE Science & Additional Science
Biology 1 Topic 7
Genetic
variation
Genetic variation and its
and its
control
control
Hodder Education Revision Lessons
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AQA GCSE Science & Additional Science
Biology 1 Topic 7
Overview
• There are differences of course between different species of
plants and animals, but there are also differences between
individuals of the same species.
• These differences are due partly to the information in the
cells they have inherited from their parents and partly to the
different environments in which the individuals live and grow.
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AQA GCSE Science & Additional Science
Biology 1 Topic 7
Genetic control
Asexual reproduction can be used to produce individuals that
are genetically identical to their parent.
Scientists can now add, remove or change genes to produce the
plants and animals they want.
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AQA GCSE Science & Additional Science
Biology 1 Topic 7
Why organisms are different 1
The information that results in plants and animals having
similar characteristics to their parents is carried by genes.
Genes are passed on in the sex cells (gametes) from which
offspring develop.
What are the gametes in humans called?
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AQA GCSE Science & Additional Science
Biology 1 Topic 7
Why organisms are different 2
The nucleus of the cell contains the chromosomes, which carry
the genes.
Different genes control the development of different
characteristics of an organism.
What characteristics have you inherited from your parents?
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AQA GCSE Science & Additional Science
Biology 1 Topic 7
Why organisms are different 3
Variation can also be caused by the conditions in which the
organism has developed (environmental factors).
What environmental factors do you show?
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AQA GCSE Science & Additional Science
Biology 1 Topic 7
Reproduction
There are two types of reproduction.
• Sexual reproduction is the joining (fusing) of male and
female gametes. This mixing of the genetic information of
two parents leads to genetic variation in the offspring.
• Asexual reproduction involves only one parent and the
offspring are genetically identical (clones).
Give an example of sexual and asexual reproduction.
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AQA GCSE Science & Additional Science
Biology 1 Topic 7
Cloning techniques
Plants can be grown from cuttings of a parent plant. Other
techniques are:
• tissue culture — using small groups of cells from the parent
plant to produce large numbers of plants
• embryo transplants — splitting apart cells in an embryo
and implanting them into host mothers
• adult cloning — removing a nucleus from an egg cell and
inserting one from a body cell; after treatment, the embryo is
implanted into a womb
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AQA GCSE Science & Additional Science
Biology 1 Topic 7
Tissue culture
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AQA GCSE Science & Additional Science
Biology 1 Topic 7
Adult cell cloning 1
Adult animals that show outstanding features can be cloned for
meat or milk production.
•
•
•
•
The nucleus is removed from an unfertilised egg cell.
A nucleus from a body cell is inserted into the egg cell.
The cell is triggered to divide via electric shocks.
This embryo has identical genetic information to the body
cell.
• This embryo is inserted into a host womb and its
development continues to produce a clone of the parent.
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AQA GCSE Science & Additional Science
Biology 1 Topic 7
Adult cell cloning 2
The procedure
for cloning
sheep
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AQA GCSE Science & Additional Science
Biology 1 Topic 7
Genetic engineering
Genetic engineers can alter the behaviour of cells by using
enzymes to ‘cut out’ genes from cells of one organism and
placing them in the cells of other organisms.
These engineered cells then take on the desired characteristics
of the genes that have been added to them.
Genetic engineering can be used to treat genetic disorders.
There are ethical issues involved with genetic engineering.
What are they?
What do you think of these issues?
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AQA GCSE Science & Additional Science
Biology 1 Topic 7
Genetic modification
Crops can also be genetically engineered to give desired
characteristics. These are called genetically modified (GM)
crops. GM crops are grown to have:
• greater yields
• drought and disease resistance
• resistance to herbicides
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AQA GCSE Science & Additional Science
Biology 1 Topic 7
Genetic modification concerns
There are concerns about the effects that GM crops might have
on:
• populations of wild plants, and the danger of cross-pollination
• insects
• health, after eating GM crops
What are your views?
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