1. 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

2. 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.

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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.

10. 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

11. Plenary Review
Reflective
Learner
Grade 4
Grade 6
Grade 8

12. Self
Manager
Reflective
Learner
Answers

13. 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