The diagram below shows the pattern of inheritance of deafness in a family. The letter H represents the allele for hearing and h represents the allele for deafness.

Here are the solutions to your questions:

2.2.1 How many of EACH of the following are represented in this diagram?

a) Males
There are three males (Jon, Paul, Lyall) represented by squares.

$$\boxed{3}$$

b) Generations
There are three generations shown in the pedigree.

$$\boxed{3}$$

2.2.2 Give the:

a) Phenotype of Jon
Jon has the genotype Hh, where H represents hearing.

$$\boxed{\text{Hearing}}$$

b) Genotype of Paul
Paul's parents are Jon (Hh) and Linda (hh). Paul can hear (unshaded square), so he must have at least one H allele. Since Linda can only pass on an h allele, Paul's genotype must be Hh.

$$\boxed{\text{Hh}}$$

2.2.3 Both Lyall's parents can hear, yet he is deaf. Explain how he inherited deafness.
Lyall is deaf, which means his genotype is homozygous recessive ($\text{hh}$). Since he inherited one 'h' allele from each parent, both of his parents (Gabby and Paul) must carry the recessive 'h' allele. As both Gabby and Paul can hear, they must also possess the dominant 'H' allele. Therefore, both Gabby and Paul are heterozygous ($\text{Hh}$). When two heterozygous parents ($\text{Hh} \times \text{Hh}$) reproduce, there is a 25% chance of their offspring inheriting two recessive alleles ($\text{hh}$), resulting in deafness.

2.2.4 Lyall marries a woman who is homozygous dominant for hearing. Use a genetic cross to show the percentage chance of them having a deaf child.
Lyall's genotype: $\text{hh}$ (deaf)
Woman's genotype: $\text{HH}$ (homozygous dominant for hearing)