Variation

18.1

What the syllabus asks of you

Describe variation as differences between individuals of the same species
State that continuous variation results in a range of phenotypes between two extremes; examples include body length and body mass
State that discontinuous variation results in a limited number of phenotypes with no intermediates; examples include ABO blood groups, seed shape in peas and seed colour in peas
State that discontinuous variation is usually caused by genes only and continuous variation is caused by both genes and the environment
Investigate and describe examples of continuous and discontinuous variation
Describe mutation as genetic change 9 Describe gene mutation as a random change in the base sequence of DNA
State that mutation is the way in which new 10 State that mutation, meiosis, random mating alleles are formed and random fertilisation are sources of genetic variation in populations
State that ionising radiation and some chemicals increase the rate of mutation

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Chapter 17: Variation

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