Answer:
Step-by-step explanation:
(a) If 60 birds were raised from a cross between individuals that were heterozygous for the gene, then according to Mendelian genetics, the offspring should segregate in a 3:1 ratio of normal to silky feathers.
To determine how many would be expected to have each phenotype, we can use a Punnett square:
L l
L LL (normal) Ll (normal)
l Ll (normal) ll (silky)
From this Punnett square, we can see that of the four possible offspring genotypes, three would result in the normal feather phenotype, and one would result in the silky feather phenotype. Therefore, we can expect 45 birds with normal feathers (3/4 of 60) and 15 birds with silky feathers (1/4 of 60).
(b) If you had a normal feathered bird, you could determine whether it is homozygous or heterozygous for the gene by crossing it with a known homozygous recessive bird (ll). If the normal feathered bird is heterozygous (Ll), then half of its offspring should have silky feathers (ll) when crossed with the homozygous recessive bird (ll). If the normal feathered bird is homozygous (LL), then all of its offspring should have normal feathers (Ll) when crossed with the homozygous recessive bird (ll). By analyzing the phenotype of the offspring, you can determine whether the normal feathered bird is homozygous or heterozygous for the gene.