In a species of lizard, the allele S S\,S for spotted skin is dominant to the allele s s\,s for plain skin.
A spotted lizard, P, was crossed with a plain lizard. The table shows the offspring produced.
| offspring phenotype | number of offspring |
|---|---|
| spotted | 48 |
| plain | 52 |
Another spotted lizard, Q, has genotype SsSsSs.
Explain what the breeding results show about the genotype of lizard P.
Lizard P could be crossed with lizard Q or with a plain lizard. Calculate and compare the probability of producing a plain offspring from each cross.
71 exam-style questions on Edexcel GCSE Biology 3.3 Inheritance, covering 3.3.1 Gregor Mendel and the basis of genetics, 3.3.2 Alleles and inherited characteristics, 3.3.3 Monohybrid inheritance, 3.3.4 Determination of sex at fertilisation, 3.3.5 Outcomes from monohybrid crosses, 3.3.6 Inheritance of ABO blood groups, 3.3.7 Inheritance of sex-linked disorders, and 3.3.8 Multiple genes and phenotypic features. Each one has a worked solution and a mark scheme showing where the marks go.