How do I work out a genetic cross?
- Note the phenotypes of the parents, work out whether they are homozygous or heterozygous.
- Choose letters to represent the alleles. The upper case letter should represent the dominant alleles and the lower case represents the recessive ones.
- The parents should be labelled and their phenotypes represented with a pair of letters.
- State the gametes each parent would produce. Label them.
- Use a Punnet square to show how the gametes would cross.
- State the phenotype of each genotype and indicate the ratio.
HD
Related Biology A Level answers
All answers ▸Explain how FHS and oestrogen illustrate the principle of negative feedback during the menstrual cycle, and explain therefore why oestrogen may be used as a contraceptive.
Describe the function of enzymes DNA helicase and DNA polymerase during DNA replication (2 marks)
What is eutrophication and what are its effects?
Explain the primary, secondary and tertiary structure of proteins