Question

Short-legged variety of sheep is an example of
(A)Recessive germline mutation
(B)Dominant germline mutation
(C)Recessive somatic mutation
(D)Dominant somatic mutation

Answer 1

Hint: Short-legged variety of sheep, also known as ancon sheep possess very short legs and was observed by Seth Wright in 1791. The short-legged trait of these sheep as a result of specific mutations.

Complete answer:
Here, in this case, the short-legged variety of sheep known as the ancon breed is an example of a recessive germline mutation.
It is because of the following reasons-
-the homozygous recessive genotype expressed the short-legged traits in the sheep while the heterozygous sheep were long-legged. That concludes that the mutation is recessive. If it were a dominant mutation, the heterozygous sheep would have possessed the short legs.
-Selfing in F1 progenies produces a large number of short-legged sheep which means that the mutation is germline, not somatic. If it were somatic, the sheeps having cells with mutant allele only will express it.

Additional Information:
A germline mutation creates a constitutional mutation in the offspring that is present in every cell of the organism. It occurs very soon after fertilization or occurs from a previous constitutional mutation in a parent.
Somatic mutation is a change in the genetic structure that is not inherited from a parent and also not passed down to an offspring. They do not affect the germline.

So, the correct answer is "Recessive germline mutation".

Note: Alleles are different forms of a single gene and as diploid organisms carry two copies of a gene, the ones carrying identical alleles is known as homozygous and the one carrying different alleles is known as heterozygous for a gene. The recessive mutation is where the organisms must be homozygous for the mutant allele in order to show a mutant phenotype. However, in the Dominant one, a mutant phenotype occurs in the presence of a normal copy of the gene and it is associated with either a loss or gain of function.