Black fur (B) is dominant to white fur (b) in guinea pigs. An F1 cross was conducted and resulted in 100% heterozygous guinea pigs (Bb). What is the genotypic ratio outcome of the F2 generation? A. 2 BB : 1 Bb : 1 bb

B. 3 Bb : 1 bb

C. 4 Bb

D. 1 BB : 2 Bb : 1 bb

The genotypic ratio outcome of the F2 generation involving 2 heterozygous (Bb) guinea pigs would be 1 BB : 2 Bb : 1 bb

From the cross below:

                 Bb     x     Bb

               BB    Bb    Bb    bb

BB - 1

Bb - 2

bb - 1

Thus, the genotypic ratio of the F2 would be 1 BB : 2 Bb : 1 bb

More on genotypic ratios can be found here: link

D. 1 BB : 2 Bb : 1 bb

Explanation:

This question involves a single gene coding for fur color in guinea pig. Black fur (B) is dominant over white fur (b). This means that, as stated in the question, if a black fur parent (BB) is crossed with a white fur parent (bb), a 100% heterozygous offspring (Bb) with black fur will result.

If two heterozygous guinea pigs are crossed i.e. Bb × Bb, the following gametes will be produced by each heterozygous parent:

Bb = B and b

Using these gametes in a punnet square (see attached image), offsprings with the following genotypic ratio will be produced:

1 BB : 2 Bb : 1 bb

BB and Bb = black fur guinea pigs

bb = white fur guinea pigs

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.