Question

The seeds from Mendel’s tall plants were round and yellow, all three characters due to a dominant gene at each of three independently assorting loci. The recessive genotypes dd, ww, and gg produce dwarf plants with wrinkled and green seeds, respectively.,

(a) If a pure, tall wrinkled and yellow variety is crossed with a pure dwarf, round, green variety, what phenotypic ratio is expected in the F₁ and F₂?

(b) What percentage of the F₂ is expected to be of genotype DdWWgg?

(c) If all the dwarf, round, green individuals in the F₂ are isolated and artificially crossed at random , what phenotypic ratio of offspring is expected?

Answer 1

a) When a pure, tall wrinkled and yellow variety is crossed with a pure dwarf, round, green variety:

DDWWGG X ddwwgg

The F1 generation will all be  DdWwGg - Tall, round and yellow.

In F2 generation, The phenotypic ratio will be 27:9:9:9:3:3:3:1, that is:

27 tall round yellow
9 tall round green
9 tall wrinkled yellow
9 dwarf round yellow
3 tall wrinkled green
3 dwarf round green
3 dwarf wrinkled yellow
1 dwarf wrinkled green

b) 3.12% will be DdWWgg out of the 64 plants.

c) 8:1 - 8 round and 1 wrinkled phenotype can be observed.