2.69 Urinary system

2.68b Osmoregulation

2.68 excretion

2.67b human organs of Excretion

2.67a excretion in plants

3.34 causes of mutation

3.34 causes of mutation

3.33 antibiotic resistance

3.32 Types of mutation

3.31 evolution

3.30 Mutation

3.29 species variation

3rd possibilty - variation in population entirely due to environmental factors e.g. home language

cannot be inherited 

3.21b

3.21a Genetic probability

3.20b pedigree 2

3.20a pedigree diagrams

3.18c Codominance