A widow's peak is a distinct V-shaped point in the hairline at the center of the forehead. This physical trait is controlled by a single gene, where the allele for having a widow's peak, represented by WWW, is dominant. A person with a straight hairline has the recessive phenotype, caused by the allele www.
Complete the table below by identifying the missing genotype name, alleles, or hairline type (widow's peak or straight) for each row:
| Genotype | Alleles | Hairline Type |
|---|---|---|
| homozygous dominant | (i) | widow's peak |
| (ii) | ww | (iii) |
| heterozygous | Ww | (iv) |
The table below lists possible genetic crosses between parents. Complete the table by determining the probability (as a decimal) of each cross producing a child with a widow's peak. One has been done for you.
| Parent genotypes | Probability of child with a widow's peak |
|---|---|
| Ww×WWWw \times WWWw×WW | (v) |
| Ww×wwWw \times wwWw×ww | 0.5 |
| Ww×WwWw \times WwWw×Ww | (vi) |
66 exam-style questions on Edexcel IGCSE Biology Inheritance. Each one has a worked solution and a mark scheme showing where the marks go.