how could the botanist best determine whether the genotype of the green-pod plant is homozygous or heterozygous?
The botanist should perform a test cross : cross the green‑pod plant with a plant that is homozygous recessive for pod color (yellow pods in peas).
Core idea
- Green pod color is dominant over yellow, so a green‑pod plant could be either homozygous (GG) or heterozygous (Gg).
- Crossing it with a recessive (gg) plant reveals its genotype by the pattern of offspring.
What to do step by step
- Choose a plant known to be homozygous recessive for pod color (yellow pods, gg).
- Cross the unknown green‑pod plant (G?) with this yellow‑pod plant and grow a large number of offspring.
- Record the pod color of all offspring plants once they mature.
How to interpret results
- If all offspring have green pods, the green‑pod parent is most likely homozygous (GG), because every offspring receives a dominant G allele.
- If the offspring show approximately half green and half yellow pods, the green‑pod parent is heterozygous (Gg), producing about 50% Gg (green) and 50% gg (yellow).
Mini Punnett square view
- Cross if parent is GG: GG × gg → all Gg (all green pods).
- Cross if parent is Gg: Gg × gg → ½ Gg (green), ½ gg (yellow).
So, the best way for the botanist to determine whether the green‑pod plant is homozygous or heterozygous is to do a test cross with a homozygous recessive (yellow‑pod) plant and analyze the offspring ratios.
Information gathered from public forums or data available on the internet and portrayed here.
