Monohybrid inheritance

What the syllabus asks of you

• Describe inheritance as the transmission of genetic information from generation to generation
• Describe genotype as the genetic make-up of an organism and in terms of the alleles present
• Describe phenotype as the observable features of an organism
• Describe homozygous as having two identical alleles of a particular gene
• State that two identical homozygous individuals that breed together will be pure-breeding
• Describe heterozygous as having two different alleles of a particular gene
• State that a heterozygous individual will not be pure-breeding
• Describe a dominant allele as an allele that is expressed if it is present in the genotype
• Describe a recessive allele as an allele that is only expressed when there is no dominant allele of the gene present in the genotype
• Interpret pedigree diagrams for the inheritance of a given characteristic
• Use genetic diagrams to predict the results of 13 Explain how to use a test cross to identify an monohybrid crosses and calculate phenotypic unknown genotype ratios, limited to 1 : 1 and 3 : 1 ratios
• Use Punnett squares in crosses which result in more than one genotype to work out and show the possible different genotypes 14 Describe codominance as a situation in which both alleles in heterozygous organisms contribute to the phenotype 15 Explain the inheritance of ABO blood groups: phenotypes are A, B, AB and O blood groups and alleles are IA, IB and Io 16 Describe a sex-linked characteristic as a feature in which the gene responsible is located on a sex chromosome and that this makes the characteristic more common in one sex than in the other 17 Describe red-green colour blindness as an example of sex linkage 18 Use genetic diagrams to predict the results of monohybrid crosses involving codominance or sex linkage and calculate phenotypic ratios