A, B, D, R, T are genes located on 5 different chromosomes. In all cases, the capital letter allele is dominant to lower case allele (i. e. A is dominant to a). In the following cross: AaBbDdRrTt (1st parent) x AabbDdrrTT (2nd parent) What fraction of progeny will genotypically resemble the 2nd parent?

Overall fraction of progeny that will genotypically resemble the second parent (AabbDdrrTT) = 1/32

Explanation:

We can calculate the fraction of progeny that will resemble the second parent by drawing a square diagram for each of the given parent genes separately and then multiplying the required gene fractions together.

First Parent = AaBbDdRrTt  

Second Parent = AabbDdrrTT

Parent Alleles       A        a

A                           AA     Aa

a                            Aa     aa

The progeny resembling the second parent genotype (Aa) = 2/4 = 1/2

Parent Alleles      B        b

b                           Bb     bb

b                           Bb     bb

The progeny resembling the second parent genotype (bb) = 2/4 = 1/2

Parent Alleles      D        d

D                           DD    Dd

d                           Dd    dd

The progeny resembling the second parent genotype (Dd) = 2/4 = 1/2

Parent Alleles      R        r

r                           Rr       rr

r                           Rr       rr

The progeny resembling the second parent genotype (rr) = 2/4 = 1/2

Parent Alleles      T        t

T                           TT    Tt

T                           TT    Tt

The progeny resembling the second parent genotype (TT) = 2/4 = 1/2

Overall fraction of progeny that will genotypically resemble the second parent (AabbDdrrTT) = 1/2 x 1/2 x 1/2 x 1/2 x 1/2 = 1/32

i'd say that the moon rock is about 2.2 billion years old.