1. Inheritance and Selection
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Inheritance and Selection

2. Variation
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Variation is a name given to differences in a species, e.g. dogs:
Variation is due to each animal having different GENETIC INFORMATION in their cells.

3. Where is this information stored?
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Genetic information is stored by genes which are arranged on chromosomes:
Section of a chromosome:
Genes for eye colour
Genes for blood group:
Genes for hair colour
Different species have different numbers of chromosomes. Humans have 46 (23 pairs) in every cell.

4. Environmental differences
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Clearly, not all differences are due to just our genes…
Variation due to inheritance only
Variation due to environment only
Variation due to a bit of both

5. Sexual reproduction
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Sexual reproduction involves two organisms of the same species. Each organism produces a GAMETE.
For example, in animals the gametes are the egg and the sperm:
When the sperm penetrates the egg the egg is fertilised and cells start to reproduce to form a new individual:

6. Sexual reproduction In plants, the gametes are the egg and pollen:
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In plants, the gametes are the egg and pollen:
Fertilisation
Any type of sexual reproduction helps a species to become more varied because the offspring inherit characteristics from both parents.

7. Selective breeding Friesian Jersey Hereford
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Friesian
I raise cows. Each type of cow is good at a certain job. The Friesian cow produces large quantities of milk, the Jersey cow produces very nice milk and the Hereford cow produces lot of beef.
Jersey
Hereford
If, for example, I want lots of milk I would only breed Friesian cows with each other – this is SELECTIVE BREEDING.

8. Words – clones, damp, independent, roots, identical
Asexual reproduction
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Plants can reproduce ASEXUALLY. The offspring are genetically ________ to the parent plant and are called _________. Two examples:
1) This spider plant has grown a rooting side branch (“stolon”) which will eventually become __________.
2) A gardener has taken cuttings of this plant (which probably has good characteristics) and is growing them in a ____ atmosphere until the ____ develop.
Words – clones, damp, independent, roots, identical