Zebrafish (Danio rerio) is an important model organism in the field of genetics. One of the first mutant genes to be studied in this species was golden. The mutant allele was discovered in a pigmentation mutant purchased from a pet store, which changed the color of the fish from the wild-type silver-white coloration to a pale golden color. Calculate the percent likelihood of golden offspring from a cross between a heterozygous wild-type male fish to a golden female fish a 0% b 50% c 25% d 100%

b

Explanation:

Let the wild type trait, the silver-white, be represented by A allele and the mutant trait, the golden color, be represented by a allele.

Heterozygous wild-type male fish would be Aa

Golden female fish would be aa

     Aa    x    aa

  Aa   Aa    aa    aa

2/4 Aa = silver-white

2/4 aa = golden color

Hence, the percent likelihood of golden offspring is 2/4 or 50%.

The correct option is b.

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