Variation Reflective Creative Self Effective Learner Thinker Manager L.O: Understand different types of variation Grade 4: List some examples of human variation and categorise into genetic causes, environmental causes, or both. Grade 6: List some examples of variation in plants and categorise these as being due to genetic causes, environmental causes, or both. Grade 8: Explain why some traits are only due to genetic causes. Explain why it is so hard to get valid results from identical-twin studies and discuss some of the issues scientists face when conducting these. Reflective Learner Creative Thinker Self Manager Effective Participator

Who?What?Why? When?Where?HoW? Pictures are of identical twins who have visable differences due to environmental variation e.g. Diet/exercise, smoking and hair dye.

Genetic causes of variation Boardworks GCSE Science: Biology Similarity and Variation Many characteristics are caused by the genes that we inherit from our parents. These are never exactly the same as either parent’s genes, but a new combination. When sex cells (gametes) are produced in the parents, genes are swapped between the chromosomes so that they are not exactly the same as the parents’. At fertilisation, any sperm could fuse with the egg, mixing the genes from both parents to form a very different combination. This means that offspring are always different to their parents, creating genetic variation. 3

Environmental causes of variation Boardworks GCSE Science: Biology Similarity and Variation It is not just genes that determine a person’s characteristics. What else has an effect on what you are like? what you eat where you live Teacher notes This slide could be used as a starting point for a discussion about what makes each student who they are – they may come up with many more examples. You could ask them to start thinking about which environmental factors have had the greatest impact on their development. how much exercise you do illness and injury your education 4

Environmental causes of variation Boardworks GCSE Science: Biology Similarity and Variation The same goes for plants!! Availability of water Availability of sunlight Access to nutrients in the soil Teacher notes This slide could be used as a starting point for a discussion about what makes each student who they are – they may come up with many more examples. You could ask them to start thinking about which environmental factors have had the greatest impact on their development. Soil pH Disease 5

Inherited and acquired characteristics Boardworks GCSE Science: Biology Similarity and Variation Some characteristics, such as eye colour and earlobe shape, are only determined by genes. These are called inherited characteristics. Other types of characteristics, such as scars and language, are not inherited but depend on environmental factors. These are called acquired characteristics. Differences in some characteristics, like body mass, are due to a combination of inherited and environmental factors. It can be difficult to say how much influence each factor has. 6

Mutation and genetic variation HIGHER LEVEL Mutation and genetic variation Boardworks GCSE Science: Biology Similarity and Variation Mutation is a change in the type or amount of DNA and is therefore another cause of genetic variation. Mutations can occur spontaneously – for example, through the incorrect copying of DNA when it replicates, or through the unequal distribution of chromosomes during cell division. Mutations can also be caused by environmental factors, such as radiation (for example, UV radiation from the sun) and certain chemicals. These factors are called mutagens. Teacher notes Students could be asked about the different effects of a mutation in a body cell and a mutation in a gamete. Mutations in body cells cannot be passed on to future generations, whereas a mutation in a gamete can be passed on. Some mutations may be beneficial, but many are harmful and increase the risk of developing diseases such as cancer. 7

Self Manager Creative Thinker TASK Self Manager Grade 4: Complete the Inherited vs Environmental Venn diagram and extension question Grade 6: Complete ‘Twin Studies’ sheet Grade 8:Complete ‘Twin studies’ sheet including the ‘Student follow-up’ question Creative Thinker

Inherited v environment Effective Participator Inherited v environment Team Worker Inherited features Environmental features Both Extension: Explain why you have classified some features as being caused by both inherited and environmental factors.

Team Worker Effective Participator Blood group   Accent Eye colour Speaking French Natural hair colour Skin colour Freckles Weight Scars Height Tooth fillings Ear piercing Tattoos Sporting ability Hair style Intelligence INHERITED Versus ENVIRONMENT Team Worker Effective Participator

Plenary Review Reflective Learner Grade 4 Grade 6 Grade 8

Self Manager Reflective Learner Answers

Variation Reflective Creative Self Effective Learner Thinker Manager L.O: Understand different types of variation Grade 4: List some examples of human variation and categorise into genetic causes, environmental causes, or both. Grade 6: List some examples of variation in plants and categorise these as being due to genetic causes, environmental causes, or both. Grade 8: Explain why some traits are only due to genetic causes. Explain why it is so hard to get valid results from identical-twin studies and discuss some of the issues scientists face when conducting these. Reflective Learner Creative Thinker Self Manager Effective Participator