Answer:
the male genotype = +/+
the female genotype = x/x
Explanation:
From the question; we are being told that:
A pair of wild type fruit flies of unknown origin are mated and produce wild type F1 offspring.
At the tail end of the question, it was stated that:
If the mutant phenotype is due to a recessive mutation in an autosomal maternal effect gene, what are the genotype of the original parents?
From the two statements above;
We assume to Let the wild type allele be : +
The gene needed for the cross will be : +/+ but we don't know yet if it is from the paternal or maternal side.
However, from the second statement; it is said that if the mutant genotype is due to recessive mutation in an autosomal maternal effect gene", we can see a clue here that the mutant genotype = x/x is coming from the maternal side(female)
SO, we can rewrite this as;
We let the male genotype to be: +/+ since the female genotype is x/x
If a cross occurs between:
+/+ and x/x
we have:
+ +
x +/x +/x
x +/x +/x
We can see that the statement is true that all the F1 offspring produced wild type offspring.
Now if these traits +/x and +/x undergo a cross for the second filial generation F2; they will definitely produce: wild types for all the offspring
Finally, from the foregoing, the result of F2 cross will also eventually yield
F3 with 75% wild type and 25% mutant
