(2)

Sickle cell anaemia and thalassemia are autosomal linked recessive disease while haemophilia is a sex linked recessive disease.

(4)

If a colourblind female (${\mathrm{X}}^{\mathrm{c}}{\mathrm{X}}^{\mathrm{c}}$) marries a man whose mother is colourblind, (${\mathrm{X}}^{\mathrm{c}}\mathrm{Y}$) then

[IMAGE 21]

All offspring would be colourblind.