State the law of segregation. Explain it with a monohybrid cross between tall and dwarf pea plants up to F2.

How to lay out the answer. Follow the frame, then write it in your own words.

1 · State the law. The two alleles of a gene do not blend; they separate during gamete formation, so each gamete gets only one.
2 · Set up the parents and gametes. P: TT (tall) × tt (dwarf); gametes T and t.
3 · Give the F1. All Tt and tall, because tall is dominant over dwarf.
4 · Self the F1 and draw the Punnett square. [Diagram: gametes T and t on each side; boxes TT, Tt, Tt, tt]
5 · Write both ratios. Phenotypic 3 tall : 1 dwarf; genotypic 1 TT : 2 Tt : 1 tt.
6 · Link to real life. Seed producers use test crosses to confirm that a new variety is true breeding.
7 · Close in one line. So the recessive allele is hidden in F1, not lost, and returns in F2 because alleles segregate.

Scoring tip: Write the gametes in circles and give both ratios. Missing the genotypic ratio usually costs a mark.