Describe natural selection with reference to: (a) variation within populations (b) production of many offspring (c) struggle for survival, including competition for resources (d) reproduction by individuals that are better adapted to the environment than others (e) passing on of their alleles to the next generation
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Understand that ionising radiation and some chemicals increase the rate of mutation
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State that mutation, meiosis, random mating and random fertilisation are sources of genetic variation in populations
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Describe a chromosome mutation as a change in the chromosome number or structure, using Down’s syndrome as an example (47 chromosomes instead of 46)
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Describe a gene mutation as a random change in the base sequence of DNA, using sickle cell anaemia as an example
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Describe the determination of sex in humans (XX and XY chromosomes)
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State that two identical homozygous individuals that breed together will be pure-breeding
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Explain why observed ratios often differ from expected ratios, especially when there are small numbers of offspring
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Use genetic diagrams, including Punnett squares, to predict the results of monohybrid crosses and calculate phenotypic ratios, limited to 1:1 and 3:1 ratios
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Understand and use the terms: dominant, recessive, phenotype, genotype, homozygous and heterozygous
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BNO Team