Monohybrid Inheritance - Genetic Cross Diagrams

✓ Engaging powerpoint
✓ Recaps previous learning
✓ Lots of short AFL tasks
✓ Past paper questions and mark scheme

This lesson on Monohybrid Inheritance is designed for KS4 Science students enrolled in the CIE Cambridge IGCSE Biology 0610 (2023-25) course. This is the third and last lesson in the topic 17 Inheritance.

The lesson recaps previous learning from other linked topics to ensure students have a strong foundation before diving into the material. It also includes concise and easy-to-understand information and a variety of quick assessment for learning tasks to help students solidify their understanding of the topic.

This resource also includes past paper questions alongside a mark scheme to further deepen students’ understanding. These questions can be printed on one sheet of A4 (using ‘two pages one sheet’ on your printing settings). These can be used during the lesson, as homework or revision.

Objectives:

• 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 8 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 monohybrid crosses and calculate phenotypic 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
• Explain how to use a test cross to identify an unknown genotype
• Describe codominance as a situation in which both alleles in heterozygous organisms contribute to the phenotype
• Explain the inheritance of ABO blood groups: phenotypes are A, B, AB and O blood groups and alleles are IA , IB and Io
• 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
• Describe red-green colour blindness as an example of sex linkage
• Use genetic diagrams to predict the results of monohybrid crosses involving codominance or sex linkage and calculate phenotypic ratios

This lesson would also be adaptable for all GCSE students (whether AQA, Edexcel, OCR) and great for KS3 Science or as a GCSE revision resource.