Question

question #1
in the swallowtail butterfly, the allele for black wings (b) is dominant over the allele for yellow wings (b). a cross between two black - wing butterflies produces a yellow - wing butterfly.
what are the correct genotype and phenotype of the offspring?
a

genotype	bb
phenotype	yellow wings

b

genotype	yellow wings
phenotype	bb

c

genotype	bb
phenotype	yellow wings

d

genotype	yellow wings
phenotype	bb

Explanation:

Step1: Recall Dominant/Recessive Traits

Dominant allele (B) masks recessive (b). Yellow wings (recessive) need genotype \( bb \) (since dominant B would show black).

Step2: Analyze Offspring Genotype/Phenotype

Offspring has yellow wings (recessive phenotype), so genotype must be \( bb \) (homozygous recessive). Phenotype is yellow wings.

Step3: Evaluate Options

• A: Genotype \( Bb \) shows black (dominant), wrong.
• B: Genotype/Phenotype mixed, wrong.
• C: \( bb \) (genotype) → yellow (phenotype), correct.
• D: Genotype/Phenotype mixed, wrong.

Answer:

C. genotype: \( bb \), phenotype: yellow wings