10.2 - ibbriner

10.2 - Inheritance

DCS Topic Code	Statement	Guidance
10.2.U1	Gene loci are said to be linked if on the same chromosome.
10.2.U2	Unlinked genes segregate independently as a result of meiosis.
10.2.U3	Variation can be discrete or continuous.
10.2.U4	The phenotypes of polygenic characteristics tend to show continuous variation.
10.2.U5	Chi-squared tests are used to determine whether the difference between an observed and expected frequency distribution is statistically significant.
10.2.A1	Morgan’s discovery of non-Mendelian ratios in Drosophila.
10.2.A2	Completion and analysis of Punnett squares for dihybrid traits.	Alleles are usually shown side by side in dihybrid crosses, for example, TtBb.
10.2.A3	Polygenic traits such as human height may also be influenced by environmental factors.
10.2.S1	Calculation of the predicted genotypic and phenotypic ratio of offspring of dihybrid crosses involving unlinked autosomal genes.
10.2.S2	Identification of recombinants in crosses involving two linked genes.	In representing crosses involving linkage, show genotypes as vertical pairs seperated by horizontal lines repesenting the chromosomes.
10.2.S3	Use of a chi-squared test on data from dihybrid crosses.