In a homozygous pea plant, axial flowers (A) are dominant over terminal flowers (a).
Draw a Punnett square board to show the gametes and offsprings when both the parent plants are heterozygous for axial flowers.
Topic: Punnett square — Aa × Aa
Answer
PARENTS: Aa × Aa Gametes: A, a and A, a
PUNNETT SQUARE A a A AA (axial) Aa (axial) a Aa (axial) aa (terminal)
OFFSPRING: 1 AA, 2 Aa, 1 aa — that is, THREE plants with AXIAL flowers to ONE with TERMINAL flowers.
Set the working out fully — parents, gametes, then the square — because marks are given for the METHOD as well as the result.
Write the gametes of one parent along the TOP and those of the other down the SIDE, then fill each box by combining the two letters that meet there.
LABEL EACH BOX WITH ITS PHENOTYPE as well as its genotype (axial or terminal). That is what makes the 3:1 ratio visible at a glance and answers part (iii) at the same time.