Question

in a group of cockatiels, some individuals have bright orange cheeks and others have pale orange cheeks. in this group, the gene for the cheek color trait has two alleles. the allele for pale orange cheeks (r) is recessive to the allele for bright orange cheeks (r). this punnett square shows a cross between two cockatiels. punnett square with r, r on top; r, r on left; cells: rr, rr, rr, rr what is the expected ratio of homozygous dominant to heterozygous to homozygous recessive offspring genotypes? choose the most likely ratio. options: 0:2:2, 2:0:2, 2:2:0

Explanation:

Step1: Identify Genotypes

First, we identify the genotypes from the Punnett square. The genotypes are \( Rr \), \( rr \), \( Rr \), \( rr \).

Step2: Classify Genotypes

• Homozygous dominant (\( RR \)): Count how many \( RR \) genotypes are present. From the Punnett square, there are 0.
• Heterozygous (\( Rr \)): Count how many \( Rr \) genotypes are present. There are 2.
• Homozygous recessive (\( rr \)): Count how many \( rr \) genotypes are present. There are 2.

Step3: Determine the Ratio

The ratio of homozygous dominant : heterozygous : homozygous recessive is \( 0:2:2 \).

Answer:

0:2:2