X-Linked Inheritance Simulator

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About This MicroSim

This simulator lets students explore X-linked recessive inheritance by selecting parental genotypes and immediately seeing the resulting Punnett square, chromosome diagram, and offspring phenotype tally. Three X-linked traits are available: color blindness, hemophilia, and Duchenne muscular dystrophy.

How to Use

1. Select Mother's genotype — homozygous normal, carrier, or affected.
2. Select Father's genotype — normal or affected.
3. Choose a trait from the dropdown to see trait-specific allele labels.
4. The Punnett square and offspring summary update instantly.
5. Read the insight box for a key takeaway about each cross.

Lesson Plan

Grade Level

9-12 (college placement Biology)

Duration

10-15 minutes

Prerequisites

• Understanding of dominant and recessive alleles
• Basic knowledge of sex chromosomes (XX female, XY male)
• Familiarity with Punnett squares

Activities

1. Exploration (5 min): Try all combinations of mother and father genotypes. Observe which crosses produce affected sons, affected daughters, or carrier daughters.
2. Guided Practice (5 min): Answer: "Why do X-linked recessive traits appear more frequently in males?" Use the carrier mother x normal father cross to support your answer.
3. Assessment (5 min): Predict the offspring ratios for a carrier mother crossed with an affected father, then check your prediction with the simulator.

Assessment

• Can students explain why sons are more likely to express X-linked recessive traits?
• Can students predict offspring genotype and phenotype ratios from parental genotypes?
• Can students identify that carrier females are phenotypically normal but can pass the allele to sons?

References

1. X-linked recessive inheritance - Wikipedia
2. Color blindness - Wikipedia
3. Hemophilia - Wikipedia