1. Monohybrid cross: involve a single pair of contrasting traits P generation True breeding different forms of trait F1 generation one form of trait expressed

2. Monohybrid cross F 2 generation (from self pollination of the F 1 ) 3/4 exhibit the same form as F 1 1/4 exhibit the contrasting form

3. Figure 3.1 Monohybrid cross:

4. Punnett square allows the genotypes and phenotypes resulting from a cross to be visualized easily

5. Punnett square – Step 1 Identify genotypes of F 1 generation determine possible gametes

6. Punnett square – Step 2 List F1 gametes on Punnett Square margins

7. Punnett square – Step 3 Identify possible fertilization outcomes (row x column)

8. Punnett square – Step 4 determine genotype and phenotype of F2 generation

9. Testcross determines if dominant phenotype is homozygous or heterozygous crosses with homozygous recessive

10. Dihybrid cross: Involves two different contrasting traits

11. Punnett square dihybrid cross 9:3:3:1 dihybrid ratio.

12. Dihybrid Cross: The product law can be used to predict the frequency with which two different phenotypes will occur simultaneously

13. Testcross of two traits