if tall (D) is dominant to dwarf (d0, and two homozygous varieties DD and dd are crossed, what kind of progeny will be produced?
Since all will be Dd, what you you think the phenotype will be?
To determine the kind of progeny that will be produced in a cross between two homozygous varieties (DD and dd) where tall (D) is dominant to dwarf (d), we need to consider the genotype of the parent plants.
The genotype of the first parent plant is DD, which means it is homozygous dominant for the tall trait. The genotype of the second parent plant is dd, which means it is homozygous recessive for the dwarf trait.
When these two parent plants are crossed, all the offspring will receive one allele from each parent to form their genotype. Since the tall trait (D) is dominant, individuals only need one copy of the dominant allele to express the tall phenotype.
The possible genotypes and phenotypes of the progeny can be determined using a Punnett square:
D D
d Dd Dd
d Dd Dd
From the Punnett square, we see that all the offspring will have the genotype Dd. Since the tall trait is dominant, all the progeny will exhibit the tall phenotype.
Therefore, the kind of progeny produced from crossing the homozygous varieties DD and dd will be all tall plants with the genotype Dd.
When tall (D) is dominant to dwarf (d), crossing two homozygous varieties with genotypes DD (tall) and dd (dwarf) will produce hybrid offspring.
The genotype of the F1 progeny will be Dd (heterozygous for tallness). Phenotypically, all the F1 progeny will be tall because the dominant trait (D) masks the expression of the recessive trait (d).
So, the progeny produced will be tall plants (phenotypically) with a genotype of Dd (heterozygous).