In sheep, coat color is influenced by two genes. Gene A influences pigment production, while gene B produces black or brown pigment. If two heterozygous white sheep were crossed and offspring were produced in a ratio of 12 white sheep to 3 black sheep to 1 brown sheep, what are the genotypes of the offspring?A) The white sheep could be A-B- or aaB-.
B) The white sheep could be A_B_ or aabb.
C) The white sheep could be A_B_ or A_bb.
D) The white sheep must all be aabb.
E) The white sheep must all be A_B_.

C) The white sheep could be A_B_ or A_bb.

Explanation:

Given that in a certain population of sheep, coat color is influenced by two genes, in which:

Gene A: influence pigment production

Gene B: influence black or brown pigment.

Since Gene B influences Black or Brown pigment production and we are given three coat color (white, black and brown), definitely, this implies that Gene A influences White  pigment production.

NOW, If two heterozygous sheep were crossed; definitely we knew our heterozygous genes will be AaBb, so if two of these were crossed;

Offspring that were produced were in the ratio of 12 white: 3 black : 1 brown

So, we are asked to deduce, what is the possible genotype of the offspring:

If a cross occur between AaBb:

i.e AaBb × AaBb

we have the following gametes for the cross: (AB, Ab, aB, ab)

                 AB                       Ab                 aB                     ab

AB            AABB                 AABb              AaBB                AaBb

Ab            AABb                  AAbb              AaBb                Aabb

aB            AaBB                   AaBb              aaBB                aaBb

ab            AaBb                   Aabb                aaBb               aabb

So, since gene A influences white pigment production; if can either be A_B_ or A_bb.

Since gene B influences black or  brown pigment production;

then aaB_ represent Black sheep

and aabb represent homozygous recessive Brown sheep.

So for white sheep; we have the following gene:

( AABB, AABb, AaBB, AaBb, AABb, AAbb, AaBb, Aabb, AaBB, AaBb, AaBb, Aabb ) = 12

Black sheep = (aaBB, aaBb, aaBb) = 3

Brown = (aabb) = 1

Therefore, The white sheep could be A_B_ or A_bb.

b a mature ovary of a plant.

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.'