1 What type of cross is this? 21.2 a) What is the phenotype of a rabbit that is dominant for both characteristics? b) What is the genotype of the white rabbit with short ears? c) What is the genotype

Question 21

21.1 This cross involves two different characteristics (fur color and ear length).
The type of cross represented is a dihybrid cross.

21.2

• a) Phenotype of a rabbit that is dominant for both characteristics:

  • Dominant fur color is brown fur (B).
  • Dominant ear length is long ears (E).
  • Phenotype: Brown fur, long ears

• b) Genotype of the white rabbit with short ears:

  • White fur is recessive, so the genotype for fur color is bb.
  • Short ears are recessive, so the genotype for ear length is ee.
  • Genotype: bbee

• c) Genotype of the gametes of a heterozygous brown rabbit with short ears:

  • A heterozygous brown rabbit has the genotype Bb.
  • A rabbit with short ears has the genotype ee (since short ears are recessive).
  • So, the genotype of this rabbit is Bb ee.
  • To find the gametes, we combine one allele for fur color with one allele for ear length.
    • From Bb, the possible alleles are B and b.
    • From ee, the only possible allele is e.
  • Possible gametes: Be, be