Question

in badgers, fur color is inherited through simple autosomal inheritance, and black fur is dominant to white fur. A black badger is crossed with a white badger. In a cete of four kits, all of the kits are black. You have asked to draw a conclusion about the black badger. What is the best conclusion you can draw from this data? a. The black badger is definitely homozygous. b. the black badger is probably homozygous. c. the black badger is definitely heterozygous. d. the black badger is probably heterozygous. e. the genotype of the black badger cannot be inferred with this information.

Answer 1

Ans. Given-

Black fur is dominant over white fur. Let the dominant allele be W and recessive allele be w.

Cross between a black badger and a white badger produces all the black badgers.

# Note that the recessive phenotype, here white fur, is only expressed in homozygous recessive condition. So, the genotype of white badger is ww.

# The dominant phenotype is expressed in both homozygous dominant as well as heterozygous condition. So, the genotype of black badger is either WW or Ww.

# During fertilization, both the parents contribute one allele to the offspring.

If the black badger were heterozygous (Ww), it would also contribute a recessive allele (w) to the offspring. The white badger (ww) would always contribute only the receive allele (w). In such case the recessive alleles from both parents would produce white-fur offspring. Since there is no white-fur offspring in F1, the black badger parent can NOT be heterozygous.

# A homozygous dominant black badger produces gametes with dominant allele W. Fusion of W (from black badger) with recessive w (from white badger) produces offspring with Ww genotype- all of them be black.

Therefore, the black badger is definitely homozygous (WW).

# So, correct option is- A. the black badger is definitely homozygous (WW).