Problem 1: Monohybrid Cross with Test Cross

Question: A tall plant of unknown genotype is test-crossed with a dwarf plant. 47 tall and 53 dwarf offspring are produced. What is the likely genotype of the tall parent?

Solution:

• Test cross offspring ratio ≈ 1:1 (47 tall : 53 dwarf ≈ 1:1 due to sampling variation)
• 1:1 ratio in test cross = heterozygous parent
• Answer: Tall parent is Tt (heterozygous)
• Cross: Tt × tt → 1 Tt (tall) : 1 tt (dwarf)