Biology · Continuity and change
D3.2 — Inheritance
Biology · SL / HL · syllabus-mapped notes
D3.2.1
Production of haploid gametes in parents and their fusion to form a diploid zygote as the means of inheritance
Explain how haploid gametes and their fusion form the basis of inheritance.
D3.2.2
Methods for conducting genetic crosses in flowering plants
Carry out a genetic cross in flowering plants, and name the P, F1 and F2 generations.
D3.2.3
Genotype as the combination of alleles inherited by an organism
Define genotype, allele, homozygous and heterozygous.
D3.2.4
Phenotype as the observable traits of an organism resulting from genotype and environmental factors
Define phenotype, and classify traits by whether genotype, environment or both determine them.
D3.2.5
Effects of dominant and recessive alleles on phenotype
Explain dominance and recessiveness, and the molecular reason behind them.
D3.2.6
Phenotypic plasticity as the capacity to develop traits suited to the environment experienced by an organism, by varying patterns of gene expression
Explain phenotypic plasticity, and why it is not heritable.
D3.2.7
Phenylketonuria as an example of a human disease due to a recessive allele
Explain PKU as a recessive disorder, and how screening and diet prevent its effects.
D3.2.8
Single-nucleotide polymorphisms and multiple alleles in gene pools
Explain SNPs and multiple alleles in a gene pool.
D3.2.9
ABO blood groups as an example of multiple alleles
Explain the ABO blood groups, and why two alleles are codominant and one recessive.
D3.2.10
Incomplete dominance and codominance
Contrast incomplete dominance with codominance, with an example of each.
D3.2.11
Sex determination in humans and inheritance of genes on sex chromosomes
Explain sex determination, and how genes on sex chromosomes are inherited.
D3.2.12
Haemophilia as an example of a sex-linked genetic disorder
Explain haemophilia, and why males are affected far more often than females.
D3.2.13
Pedigree charts to deduce patterns of inheritance of genetic disorders
Deduce patterns of inheritance from pedigree charts.
D3.2.14
Continuous variation due to polygenic inheritance and/or environmental factors
Contrast discrete and continuous variation, using skin colour as a polygenic example.
D3.2.15
Box-and-whisker plots to represent data for a continuous variable such as student height
Construct and read box-and-whisker plots, and choose the right measure of central tendency.
D3.2.16
Segregation and independent assortment of unlinked genes in meiosis
Explain segregation and independent assortment as consequences of meiosis.
D3.2.17
Punnett grids for predicting genotypic and phenotypic ratios in dihybrid crosses involving pairs of unlinked autosomal genes
Use a Punnett grid to predict genotypic and phenotypic ratios in a dihybrid cross.
D3.2.18
Loci of human genes and their polypeptide products
Explain what a gene locus is, and how to find a gene's locus and product.
D3.2.19
Autosomal gene linkage
Explain autosomal gene linkage, and how to represent it in a diagram.
D3.2.20
Recombinants in crosses involving two linked or unlinked genes
Explain recombinants, and use their frequency to tell linked from unlinked genes.
D3.2.21
Use of a chi-squared test on data from dihybrid crosses
Use a chi-squared test to assess whether dihybrid cross data fit a predicted ratio.