A2 Assessment Unit BY5: 5.4 Inheritance

(a) The importance of meiosis and fertilisation in sexual reproduction giving rise to variation. Random assortment, crossing over and fertilisation as sources of variation.
(b) Alleles as different forms of the same gene. An understanding of the principles of monohybrid and dihybrid Mendelian inheritance. Chi squared. Codominance. Linkage. Sex linkage as illustrated by haemophilia.
(c) Gene mutation as illustrated by sickle cell anaemia and chromosome mutation as illustrated by Down's syndrome. Mutagens and carcinogens. Oncogenes
Suggested Practical Activities: Experiment to illustrate gene segregation (Drosophila, maize cobs and tomato plants are suitable, but other material may be used). Fast cycling brassicas (SAPS).

A2 Assessment Unit BY5: 5.6 Applications of reproduction and genetics

(b) The Human Genome Project has been used to locate and sequencealleles on human chromosomes. The potential uses and abuses of this knowledge. Possibility of automated routine screening for particular predisposing genes. Ethical issues surrounding this knowledge and gene ownership.