Pure-breeding snails with unbanded shells were crossed with pure-breeding snails with banded shells. All the first-generation snails had unbanded shells. Two first-generation snails were then crossed, and some of their offspring had banded shells.
Which combination of inherited alleles produced each banded offspring?
One unbanded-shell allele from each first-generation parent.
One banded-shell allele from each first-generation parent.
One banded-shell allele and one unbanded-shell allele, with both fully expressed.
Two banded-shell alleles from one first-generation parent and none from the other.
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.