9 a inheritance & selection (boardworks)

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  • 1. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 20051 of 28 KS3 Biology 9A Inheritance and Selection
  • 2. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 20052 of 28 9A Inheritance and Selection Contents Types of variation Causes of variation Summary activities Variation investigation Selective breeding
  • 3. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 20053 of 28 What characteristics have been passed on in this family? Family characteristics
  • 4. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 20054 of 28 The members of this family tree are related and so they share certain similar characteristics. Inherited characteristics Shared family characteristics are inherited from parents. So why don’t all family members look exactly alike?
  • 5. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 20055 of 28 Variation can come about for two reasons. What are they? 1. People inherit characteristics from both of their parents and each person gets a different combination of features. This is called inherited variation. 2. Other characteristics are affected a person’ surroundings. This called environmental variation. Which features are environmental and which are inherited? Different types of variation People are similar, but not identical, to their parents or each other. The differences in a species are called variation.
  • 6. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 20056 of 28 Variation – environmental or inherited?
  • 7. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 20057 of 28 9A Inheritance and Selection Contents Types of variation Causes of variation Summary activities Variation investigation Selective breeding
  • 8. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 20058 of 28 Deciding whether a characteristic is inherited or environmental can cause a lot of discussion. Scientists have now decided that only four features are truly inherited and not affected by the environment at all. What are the four truly inherited characteristics? natural eye colour Inherited characteristics only? natural hair colour blood group some inherited diseases
  • 9. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 20059 of 28 From a cell to DNA
  • 10. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200510 of 28 Fertilization and cell division – animation
  • 11. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200511 of 28 Identical twins – animation
  • 12. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200512 of 28 Non-identical twins – animation
  • 13. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200513 of 28 Apart from eye colour, natural hair colour, blood group and some inherited diseases, all other features are caused by a mixture of inheritance and environmental factors. What environmental factor might affect skin colour? What causes other features? The shape of this person’s nose is just like their mum’s nose. However their nose was broken and ended up with a kink in it. So, the initial nose shape was inherited, but over time it has been affected by the environment. Is nose shape an inherited or environmental characteristic?
  • 14. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200514 of 28 Variation in humans can be due to inherited factors, environmental factors or a combination of both factors: Inherited variation When humans reproduce via sexual reproduction, the nuclei of the male sex cell and the female sex cell fuse. This cannot happen the same way twice, which makes each individual unique. Variation summary Environmental variation Some features are due to the conditions in a person’s surroundings. For example, accent is just affected by environment but skin colour is due to both inherited and environmental factors.
  • 15. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200515 of 28 9A Inheritance and Selection Contents Types of variation Causes of variation Summary activities Variation investigation Selective breeding
  • 16. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200516 of 28 Eric bought 50 beefsteak tomatoes for his restaurant. The mass of each tomato was measured (in grams) and the results are given in the following table. 78.5 108.3 111.3 102.1 94.4 113.2 100.2 95.7 109.7 113.5 83.2 106.4 102.1 99.8 102.4 118.1 105.6 112.7 103.8 89.2 110.8 105.2 112.6 93.8 88.9 99.6 109.4 99.8 109.4 108.8 84.8 91.9 97.1 91.7 111.8 98.4 97.5 109.0 92.1 99.2 100.4 98.6 103.7 109.3 104.6 102.3 87.4 97.3 119.3 96.1 Variation investigation – beefsteak tomatoes
  • 17. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200517 of 28 The masses of the beefsteak tomatoes can be made into a frequency graph by counting how many tomatoes weigh between 78g and 82g, 82g and 96g and so on. Variation investigation – beefsteak tomatoes What does this graph show? Distribution of Mass of Beefsteak Tomatoes mass (g) frequency
  • 18. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200518 of 28 Eric also bought 50 plum tomatoes from the local farm, which were also weighed. The masses (in grams) of this second type of tomatoes are listed in the table below: 40.0 62.2 65.3 58.1 73.0 74.4 61.3 71.0 48.1 71.6 59.0 63.9 64.4 44.9 59.8 60.5 71.1 62.0 64.4 65.7 56.3 55.7 50.2 55.6 52.3 59.4 68.3 61.8 54.7 59.4 49.7 71.9 71.2 46.5 42.0 58.6 60.6 63.7 64.5 59.6 43.1 58.2 60.1 68.3 72.5 57.2 63.1 48.5 64.5 47.7 Variation investigation – plum tomatoes
  • 19. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200519 of 28 The masses of the plum tomatoes can be displayed in a frequency graph by counting how many tomatoes weigh between 40 g and 44 g, 44 g and 48 g and so on. Variation investigation – plum tomatoes Distribution of Mass of Plum Tomatoes mass (g) frequency What does this graph show?
  • 20. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200520 of 28 Variation investigation – comparing results Compare the frequency graphs for the masses of the beefsteak and plum tomatoes. mass (g) frequency Distribution of Mass of Beefsteak Tomatoes Distribution of Mass of Plum Tomatoes frequency mass (g)  Are there any differences between the two sets of results?
  • 21. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200521 of 28  Are there any other measurements of the tomatoes that can be easily recorded and would show a similar set of results to the measurements of mass?  Some quantities cannot be measured immediately but are important to those who grow and those who buy a crop of tomatoes, e.g. disease resistance and time taken to ripen. Can you think of any more quantities like this? Variation investigation – analyzing results Other questions to consider when comparing the frequency graphs for the masses of the beefsteak and plum tomatoes.  What can you say about the variation of mass within each species of tomato and the variation between the two sets of results?
  • 22. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200522 of 28 9A Inheritance and Selection Contents Types of variation Causes of variation Summary activities Variation investigation Selective breeding
  • 23. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200523 of 28 Selective breeding is a process used to produce different breeds of animals or varieties of plants that have useful characteristics. Farmers can choose individual cows to mate in order to produce a generation of cows that will yield more milk. Apple growers want to produce a type of apple that is tasty and resistant to disease. This can be done by crossing a variety of apple known for taste with another variety that shows strong resistance to disease. What is selective breeding?
  • 24. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200524 of 28 Selective breeding – true or false?
  • 25. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200525 of 28 9A Inheritance and Selection Contents Types of variation Causes of variation Summary activities Variation investigation Selective breeding
  • 26. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200526 of 28 Glossary  characteristics – The features of a living thing.  environmental variation – Differences in characteristics caused by surroundings or living conditions.  inherited variation – Differences in characteristics that are passed on from parents to offspring.  natural selection – Passing on inherited characteristics that make living things best adapted for survival.  selective breeding – Producing specific offspring that have useful characteristics of both parents.  variation – The differences in characteristics between living things.
  • 27. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200527 of 28 Anagrams
  • 28. © Boardworks Ltd 20041 of 20 © Boardworks Ltd 200528 of 28 Multiple-choice quiz