Imagine that long fins in zebrafish is a dominant trait. a breeder wants to set up a breeding program beginning with homozygous dominant long-finned fish. if she obtains a handful of the long-finned fish, how can she tell which if any of these are homozygous for the trait? a. cross the long-finned fish with short-finned fish; if three-fourths of the offspring are long-finned and one-fourth are short-finned, the long-finned parent is homozygous. b. cross the long-finned fish with short-finned fish; if half the offspring are long-finned and half are short-finned, the long-finned parent is homozygous. c. cross the long-finned fish with short-finned fish; if four-fifths of the offspring are long-finned and one-fifth are short-finned, the long-finned parent is homozygous. d. cross the long-finned fish with short-finned fish; if the offspring are all long-finned, the long-finned parent is homozygous.

D - Cross the long-finned fish with short-finned fish; if the offspring are all long-finned, the long-finned parent is homozygous.

Explanation:

Since long fins is a dominant trait, a cross between homozygous dominant long-finned fish and short-finned fish should results in all long-finned offspring.

If long fin allele is L, homozygous long fin will be LL and short fin will be ll

                  LL    x    ll

This will result in Ll, Ll, Ll, Ll genotype offspring and since L is dominant, all the offspring will have long fin.

Hence, in order to for the breeder to tell which of the long-finned fish is/are homozygous for the trait, all she needs to do is mate each of the long-finned fishes with a short-finned fish. Anyone that yields all long-finned offspring is homozygous for the trait.

The correct option is D.

ans.

dna fingerprinting is defined as a process that determines the dna characteristics of an individual. these dna characteristics are unique among individuals as their fingerprints, so it is known as dna fingerprinting.

steps of dna fingerprinting includes extraction of dna from sample, amplification of dna, restriction digestion of amplified dna, and then analysis of dna by gel electrophoresis, respectively.

thus, the next step performed by the scientist is 'to cut the amplified dna (obtained by polymerase chain reaction) by restriction enzymes that cleave the dna into fragments and their analysis.'