In fruit flies, curved wings are recessive to normal wings, and ebony body is recessive to gray body. a cross was made between two true-breeding flies, one with normal wings and gray body, the other a fly with curved wings and ebony body. the f1 offspring were thus hybrids. these hybrids were crossed to each other (dihybrid cross). for observations, 120 flies were collected. if these traits are independently assorting, what is the expected number of flies with curved wings and gray body

23 flies

Explanation:

Let true breeding flies with normal wings and gray body : AABB

Let true breeding flies with curved wings and ebony body: aabb

Their cross: AABB X aabb = AaBb ( F1 progeny )

Ratio in F2 progeny when F1 progeny is self crossed ( considering independent assortment)

AaBb X AaBb =

flies with normal wings, gray body: 9

flies with normal wings, ebony body: 3

flies with curved wings, gray body: 3

flies with curved wings, ebony body: 1

Here, 120 flies were collected. According to the ratio of independent assortment number of flies with curved wings and gray body:

(3/16) * 120 = 22.5 = almost 23 flies

answer: b

coz red blood cells marrow and circulates the body for 120 days.