Genetic Inheritance in Brassica rapa

Students investigate Mendelian inheritance in Brassica rapa by studying two traits: stem height (tall vs. dwarf) and stem color (purple vs. green). They grow F1 and F2 generations, predict outcomes with Punnett squares, then compare predictions with actual phenotypic ratios using class data.

1. Begin with seeds from two crossbred parent lines that are homozygous dominant for one trait and homozygous recessive for the other.
2. Plant F1 seeds and record phenotypes (tall vs. dwarf, purple vs. green stems).
3. Infer genotypes of the F1 plants from the observed phenotypes.
4. Use Punnett squares to predict expected genotype and phenotype ratios for the F2 generation.
5. Plant F2 seeds, grow them under controlled conditions, and record phenotypes for both traits.
6. Compile individual and combined class data to increase sample size.
7. Compare observed results with predictions, analyze discrepancies, and calculate ratios.

Biology 1107 Lab 2 || Plant Genetics - aceconnect:

📄 Genetic inheritance in Brassica rapa - Australian Curriculum: https://v8.australiancurriculum.edu.au/resources/work-samples/samples/genetics-practical-above/

* Test additional traits in Fast Plants, such as leaf color (yellow-green vs. green) or rosette growth habit.

• Use digital tools to simulate Punnett squares and compare with experimental outcomes.

• Wash hands after handling soil, fertilizer, and plant tissue.
• Keep water away from electrical grow lights and equipment.
• Use scissors or cutters safely when trimming plants.

• What phenotypes were observed in the F1 generation? What does this reveal about dominance? (All F1 were tall and purple, showing T and P are dominant.)
• What ratios did you predict for the F2 generation using a Punnett square? (Expected 9:3:3:1 phenotypic ratio for tall-purple : tall-green : dwarf-purple : dwarf-green.)
• How close were the observed ratios to predictions? Were deviations due to chance, environment, or experimental error?
• How does combining class data improve reliability compared to using only one group’s results?
• What evidence supports Mendel’s laws of segregation and independent assortment in your experiment?