Chapter 12 / 9 short lessons
Inheritance
Use genetic language and diagrams to predict offspring, interpret chance variation and distinguish kinds of mutation.
G3 Combined Biology / K327 / K328 / 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 9 marked as readOne gene, different alleles
Distinguish a gene from an allele and locate alleles on homologous chromosomes.
About 4 minContinuous or discontinuous variation?
Distinguish continuous and discontinuous variation and interpret suitable examples.
About 5 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 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 minWhat you will be able to do
- Distinguish genetic terms and forms of variation.
- Construct 3:1 and 1:1 crosses and interpret observed differences.
- Explain the usual XX/XY model and gene/chromosome mutations.
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