In a garden pea, the axial flower is dominant to terminal flower. What will be the percentage of offsprings with terminal flowers, when two heterozygous plants are crossed?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 25%
Let A = axial (dominant) and a = terminal (recessive). Both parents are heterozygous: Aa × Aa.
Gametes from each parent: A and a.
Offspring: 1 AA : 2 Aa : 1 aa. AA and Aa have axial flowers; only aa has terminal flowers.
Terminal = 1 out of 4 = 25%.
Option (1) 25% — Correct. Crossing two heterozygous plants, Aa × Aa, gives AA, Aa and aa in the ratio 1 : 2 : 1. Only aa shows the recessive terminal flower, so 1 in 4, or 25%, have terminal flowers.
Option (2) 50% — Incorrect. 50% is the share of heterozygous (Aa) plants, which are axial.
Option (3) 75% — Incorrect. 75% is the share of axial plants.
Option (4) 0% — Incorrect. Both parents carry a, so aa plants do appear.