Monohybrid cross (Punnett square)एकसंकर संकरण (पुनेट वर्ग)
NCERT Figs 4.3–4.4 · Class 12 Biology · Chapter 4 · interactive diagram
Parts and their functions
- Tall parent (TT) (लंबा जनक (TT)) — True-breeding tall pea plant; homozygous TT. Makes only T gametes.
- Dwarf parent (tt) (बौना जनक (tt)) — True-breeding dwarf pea plant; homozygous recessive tt. Makes only t gametes.
- Gametes (युग्मक) — Law of segregation: each gamete gets only one allele of the pair — T from the tall parent, t from the dwarf parent.
- F₁ hybrid (Tt) (F₁ संकर (Tt)) — Heterozygous Tt; all F₁ plants are tall because T is dominant over t (law of dominance).
- TT — 1/4 (TT — 1/4) — Homozygous tall: 1/4 of the F₂.
- Tt — 1/2 (Tt — 1/2) — Heterozygous tall: 2 of 4 boxes = 1/2 of the F₂. Looks like TT; only a test cross can tell them apart.
- tt — 1/4 (tt — 1/4) — Homozygous dwarf: 1/4 of the F₂. The recessive trait hidden in F₁ reappears.
Steps
- 1 · Parents: true-breeding tall (TT) × dwarf (tt).
- 2 · Gametes: T and t (one allele each).
- 3 · F₁: all tall, genotype Tt.
- 4 · F₂ (selfing F₁): 3 tall : 1 dwarf; 1 TT : 2 Tt : 1 tt.
Original diagram drawn by Simple Learning Hub, based on NCERT Figs 4.3–4.4. Report a mistake