1. Variation and Inheritance LO: To learn how characteristics can vary.
with…

2. The Mr Men Match.

3. Variation Ways in which Tom and James are the same (caused by genes):
“Variation” is the name given to differences between individuals of the SAME species.
Variation is due to GENETIC or ENVIRONMENTAL causes. For example, consider identical twins:
Ways in which Tom and James are the same (caused by genes):
Ways in which Tom and James are different (caused by environment):
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4. What’s that then?

5. Genes, Chromosomes and DNA
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6. Where is this information stored?
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.
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7. Genes
Human cells have 46 chromosomes other organisms have different numbers of chromosomes.

8. Sexual Reproduction
The human egg and sperm cell (“GAMETES”) contain 23 chromosomes each.
When fertilisation happens the gametes fuse together to make a single cell called a ZYGOTE. The zygote has 46 chromosomes (23 pairs).
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9. So what causes variation?

10. Meet our Mr Men
And our Little Misses
Now lets meet their children!

12. What did we learn from this?
Children inherit features from their parents
If two parents have a certain characteristic then their child may show it even more (e.g. Mr Small + Little Miss Tiny = Mr Very Small!)
Some things such as glasses, scars and muscles we get from our environment, they are not inherited.

13. Genetic information
The instructions that make up a plant or animal comes from their parents.
½ comes from the sperm and ½ from the egg
These instructions are found in the nucleus of the cells.
The instructions for each characteristic are called GENES.

14. We saw that when Mr Small and Little Miss Tiny produced a child it was even smaller.
What would happen if Mr Very Small had a child with Little Miss Miniscule??

15. This is called selective breeding and can be used to make larger animals and crops that produce more fruit
Large fruited Mum
Large fruited Dad
Very large fruited child!
At this point give out picture of the giant bull.

16. This is depending on the strength of the genes...
Some genes have more clout when it comes to deciding a feature than others.
“Stronger” genes are known as dominant
“Weaker” genes are known as recessive.
The gene for brown eye colour is dominant. If one of your parents have brown eyes it is very likely you will too!
There’s still a small chance of blue eyes but the probability is decreased.

17. Variation
Level 4 – Recognise difference between organisms of the same species
Level 5 – Explain what may have caused some examples of variation within a species
Level 6 – Suggest why variation might increase an organisms chances of survival
Level 7 – Explain, using variation, why certain species have become extinct

18. Variation…your task
You have been asked to produce a poster for Year 8 students to teach them about ‘variation’.
Use you LOs as your level ladder for this task and tick them off as you go 
Key words;
Variation
Gene
Inherit
Environmental
Survival
Extinction
Organism
Don’t forget to include the two types
of variation and examples of each!

19. Lets see what you’ve learned:
Farmer Hemming wants to breed cows that are large and meaty so that he can sell them for more.
What advice would you give him in order to produce larger cows?
2. He can’t seem to breed cows with nose rings! Why not?
3. How many chromosomes are in your cells?