In a breed of cattle, the allele for no horns (H\text{H}H) is dominant to the allele for horns (h\text{h}h).
A farmer has a bull with no horns but does not know its genotype. The bull is crossed with several cows that have horns. All 12 of the calves have no horns.
Which conclusion is most likely?
The bull is Hh\text{Hh}Hh, because the cows with horns can only pass on h\text{h}h.
The bull is HH\text{HH}HH, as an Hh\text{Hh}Hh bull would give some calves with horns.
The bull is hh\text{hh}hh, because having horns is the recessive characteristic.
The bull's genotype cannot be found, because all of the calves look the same.
186 exam-style questions on OCR GCSE Biology 5.1 Inheritance, covering 5.1.1 The genome, 5.1.2 Environment and phenotype, 5.1.3 Variants and mutations, 5.1.4 How genetic variants influence phenotype, 5.1.5 Asexual and sexual reproduction, 5.1.6 Haploid and diploid, 5.1.7 Meiotic cell division, 5.1.8 Single gene inheritance, 5.1.9 Predicting single gene crosses, 5.1.10 Sex determination, 5.1.11 Multiple gene inheritance, and 5.1.12 Development of our understanding of genetics. Each one has a worked solution and a mark scheme showing where the marks go.