in the cross bb x bb (two heterozygous mice), what percentage of the offspring would you predict to have the…

in the cross bb x bb (two heterozygous mice), what percentage of the offspring would you predict to have the same phenotype as the parents? 0% 25% 50% 75% 100% done next, you perform a cross with a mouse with black fur and a mouse with white fur. which result(s) for the offspring would confirm that the mouse with black fur was heterozygous? 4 mice with black fur 8 mice with black fur, 1 mouse with white fur 5 mice with black fur, 6 mice with white fur 6 mice with black fur, 2 mice with white fur done

in the cross bb x bb (two heterozygous mice), what percentage of the offspring would you predict to have the same phenotype as the parents? 0% 25% 50% 75% 100% done next, you perform a cross with a mouse with black fur and a mouse with white fur. which result(s) for the offspring would confirm that the mouse with black fur was heterozygous? 4 mice with black fur 8 mice with black fur, 1 mouse with white fur 5 mice with black fur, 6 mice with white fur 6 mice with black fur, 2 mice with white fur done

Answer

Explanation:

Step1: Set up Punnett - square

The cross is Bb x Bb. The possible gametes from each parent are B and b. The Punnett - square has 4 boxes:

B b
B BB Bb
b Bb bb

Step2: Determine phenotypes

BB and Bb have the same phenotype (dominant phenotype, assuming B is for black fur). The ratio of BB:Bb:bb is 1:2:1. The proportion of offspring with the dominant phenotype (same as parents) is $\frac{1 + 2}{4}=\frac{3}{4}=75%$.

For the second part: If a black - furred mouse (could be BB or Bb) is crossed with a white - furred mouse (bb), a heterozygous black - furred mouse (Bb) will produce offspring in a 1:1 ratio of black (Bb) to white (bb) fur. 6 mice with black fur and 2 mice with white fur is a 3:1 ratio which is not correct. 4 mice with black fur doesn't give enough information. 8 mice with black fur and 1 mouse with white fur is not a 1:1 ratio. 5 mice with black fur and 6 mice with white fur is not a 1:1 ratio. A 1:1 ratio of black to white fur in the offspring would confirm the black - furred mouse is heterozygous.

Answer:

75% 6 mice with black fur, 2 mice with white fur