Chapter 14 / 11 short lessons
Inheritance
Read genetic diagrams, predict offspring probabilities and explain how inherited variation can change a population over generations.
G3 Pure Biology / K325 / 2027 syllabus
What do you think?
A cross predicts a 3:1 ratio. Must every group of four offspring contain exactly three of one phenotype?
Lessons
0 of 11 marked as readOne gene, different alleles
Distinguish a gene from an allele and locate alleles on homologous chromosomes.
About 4 minGenotype, phenotype and dominance
Use dominant, recessive, homozygous, heterozygous, genotype and phenotype correctly.
About 5 minFrom parents to F1 and F2
Construct a complete-dominance cross through F1 and F2, distinguishing genotype and phenotype ratios.
About 6 minExplain a 1:1 cross
Use a heterozygote-by-recessive cross to predict outcomes and interpret evidence about genotype.
About 5 minExpected ratios are probabilities
Explain chance differences between expected and observed inheritance ratios, especially in small samples.
About 5 minPedigrees and human disorders
Read pedigrees of human disorders, set out genetic diagrams for them and calculate combined probabilities such as an affected boy.
About 7 minABO: more than two alleles
Explain codominance and multiple alleles using ABO genotypes and phenotypes.
About 6 minThe usual XX and XY model
Use a genetic diagram to explain the usual chromosomal determination of sex in humans.
About 4 minGene and chromosome mutations
Describe gene and chromosome-number mutations, with sickle-cell anaemia, Down syndrome and factors increasing mutation rate.
About 5 minContinuous or discontinuous variation?
Distinguish continuous and discontinuous variation and interpret suitable examples.
About 5 minNatural selection and evolution
Explain differential survival and reproduction, environmental selection and inherited population change over generations.
About 6 minWhat you will be able to do
- Distinguish a gene, its alleles and the characteristics expressed.
- Construct monohybrid crosses and interpret expected ratios.
- Explain ABO inheritance and the usual XX/XY model.
- Connect mutation, variation and selection to population change.
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