a cross is performed between a bird that is homozygous for red feathers and a bird that is homozygous for…
a cross is performed between a bird that is homozygous for red feathers and a bird that is homozygous for blue feathers. purple offspring result due to incomplete dominance. then, two of the purple offspring are crossed. what proportion of the offspring from the second cross will be purple?\n1 in 4\n2 in 4\n3 in 4\n4 in 4
Answer
Explanation:
Step1: Define alleles
Let R represent the allele for red feathers and B represent the allele for blue feathers. The homozygous red - feathered bird has genotype RR and the homozygous blue - feathered bird has genotype BB. The purple offspring have genotype RB due to incomplete dominance.
Step2: Set up the second cross
When two purple (RB) birds are crossed, we use a Punnett - square. The possible gametes from each parent are R and B. The Punnett - square has the following combinations:
| R | B | |
|---|---|---|
| R | RR | RB |
| B | RB | BB |
Step3: Count the genotypes
From the Punnett - square, we have 1 RR (red), 2 RB (purple), and 1 BB (blue).
Answer:
2 in 4