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OCR Biology A
20.6 Speciation & artificial selection
Teacher notes
Selective breeding in humans
Specification references
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6.1.2
HSW1, HSW2, HSW9, HSW10, HSW11, HSW12
Introduction
In this activity Charles Darwin’s theory of natural selection and whether Mendel’s
theory application of his laws of segregation to human selection is good science is
discussed.
Chapter 20 Patterns of inheritance and variation and 20.6 Speciation and artificial
selection will be useful resources from the Student book.
Learning outcomes
After completing the worksheet students should be able to:
 understand that sometimes theories and models used to explain
observations are based on invalidated evidence
 explore how bad science occurs when observations from the ‘real
world’ are selected to fit the demands of a pre-existing theory. How
looking for patterns and trends must be objective, otherwise personal
beliefs influence interpretation
 appreciate that science can be used subjectively to support
particular political and social motivations
 investigate how science may aim to benefit the majority, but can
negatively affect the minorities.
Teacher notes
It would be useful to introduce the activity with a review of Charles Darwin and natural
selection. A recap of Mendel’s theory would prepare students to consider whether the
application of his laws of segregation to human selection is good science.
Discuss with students what their feelings and thoughts are about quoted terms such as
‘desirables’, ‘undesirables’, ‘human stock’, ‘unfit’, ‘socially good’, and ‘Grade A individuals’.
These terms are subjective; who decides on which individuals and traits fit into each
category? Should scientific knowledge be trusted or deployed to support political or social
objectives?
Answers
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To ‘improve’ society and human population.
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That all perceived negative traits, such as alcoholism, etc. were
controlled only by genetics, and that there were no environmental effect.
(1 mark)
© Oxford University Press 2016 www.oxfordsecondary.co.uk/acknowledgements
This resource sheet may have been changed from the original
1
OCR Biology A
20.6 Speciation & artificial selection
Teacher notes
Use evidence to show that environment has an impact on the frequency of mental
health and disorders. Also, genes could be recessive, and so sterilisation of only
those with the metal disorders would not prevent them arising in the offspring of
carriers or for mutations to occur during meiosis that could cause the disorder.
(2 marks)
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Students should consider:

Who: leaders, healthcare professionals, scientists, consider the difference
between age groups, culture, religion, etc.
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How: what is ‘unfit’ – quality of life, disability, illness, prevents someone
working, or needs regular care, negative impact on people living with the
disorder.
Deafness is an example that could be considered a disability or a different
culture.
(2 marks)
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Student should consider:

Both are discrimination against some members of society as they are deemed
‘unfit’, instead of aiming to help them.
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Both aim to ‘improve’ the fitness of the human population.
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Positive eugenics used propaganda to encourage behaviour changes, it was
optional.
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Negative eugenics enforced sterilisation.
(2 marks)
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Students should consider:

Prenatal diagnosis gives parents a choice, it is not enforced like negative
eugenics. The aim is to allow parents to give a choice based on their personal
opinions not those of society.
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Genetic counselling aims to give informed choices
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Prejudice in the population could lead to parents choosing to not proceed with
a pregnancy due to a higher risk of a physical or mental disorder.
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Is more common when there is a risk of a disorder, so could be considered to
be targeting the ‘less fit’ members of society.
(3 marks)
© Oxford University Press 2016 www.oxfordsecondary.co.uk/acknowledgements
This resource sheet may have been changed from the original
2