Topic: Monohybrid Inheritance
Lesson 1: Introduction to Inheritance
| Section | Details |
|---|---|
| Objective | – Define inheritance and explain the transmission of genetic information across generations. |
| Activities | Starter (5 mins): Show images of parent and offspring organisms (e.g., humans, animals, plants) and discuss inherited traits. Main (25 mins): 1. Define inheritance, genotype, phenotype, homozygous, and heterozygous. 2. Explain dominant and recessive alleles with examples. Plenary (10 mins): Students classify given traits as dominant or recessive and identify examples of genotype and phenotype. |
| Resources | Diagrams of genetic traits, whiteboard, and marker pens. |
| Time | 40 minutes |
| Homework | Write examples of inherited traits in humans and explain whether they are dominant or recessive. |
| Assessment | Class participation and ability to define key terms. |
| Past Paper Practice | IGCSE Biology 0610/22/O/N/20 Q4(a). |
Lesson 2: Predicting Monohybrid Crosses
| Section | Details |
|---|---|
| Objective | – Use Punnett squares and genetic diagrams to predict monohybrid crosses and calculate phenotypic ratios. |
| Activities | Starter (5 mins): Ask students why some offspring look different from their parents. Main (25 mins): 1. Explain how to use Punnett squares for monohybrid crosses. 2. Work through examples of 1:1 and 3:1 phenotypic ratios. 3. Interpret pedigree diagrams to trace inheritance. Plenary (10 mins): Students solve a simple genetic cross using a Punnett square. |
| Resources | Punnett square templates, example pedigree charts, and whiteboard. |
| Time | 40 minutes |
| Homework | Solve practice problems involving Punnett squares and calculate phenotypic ratios. |
| Assessment | Student accuracy in predicting genetic outcomes using Punnett squares. |
| Past Paper Practice | IGCSE Biology 0610/31/M/J/20 Q3(b). |
Lesson 3: Codominance and Sex-Linked Traits
| Section | Details |
|---|---|
| Objective | – Explain codominance and sex-linked inheritance, using genetic diagrams to predict outcomes. |
| Activities | Starter (5 mins): Show ABO blood group chart and explain codominance. Main (25 mins): 1. Discuss codominance with ABO blood group inheritance. 2. Explain sex-linked characteristics with red-green color blindness as an example. 3. Use genetic diagrams to predict phenotypic ratios for codominance and sex-linked traits. Plenary (10 mins): Quick quiz on codominance and sex-linked inheritance. |
| Resources | ABO blood group chart, sex-linked trait diagrams, and sample genetic problems. |
| Time | 40 minutes |
| Homework | Create a genetic diagram to predict offspring with ABO blood groups for given parental genotypes. |
| Assessment | Ability to interpret and construct genetic diagrams for codominance and sex-linked inheritance. |
| Past Paper Practice | IGCSE Biology 0610/41/M/J/21 Q2(a). |
Key Notes for Teachers:
- Relate monohybrid inheritance to real-life examples (e.g., eye color, blood types).
- Ensure students understand how to construct and interpret Punnett squares before moving to complex examples.
- Use visual aids for codominance and sex-linked traits to improve comprehension.
Key Notes for Students:
- Dominant traits are expressed even if only one allele is present, while recessive traits require two copies.
- Codominance occurs when both alleles contribute equally to the phenotype (e.g., blood types).
- Sex-linked traits are often more common in males because they have only one X chromosome.
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