A test cross is done with an organism that is a dihybrid for two unlinked autosomal genes. What proportion of the progeny will be true-breeding for both genes? 0%, 25%, 50%, 75%, 100%


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John McCann Profile
John McCann answered

25% of course!

Do your cross by Punnet square or branching line and see that only four true breeders for the original cross will be your outcome.

Looks something like this.

Aa X Bb

--------------The rest will be mixes of the above and not true breeders.

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John McCann
John McCann commented
No, I am ethologist. This is pretty standard genetics though.
Charles Davis
Charles Davis commented
Hmm so you're closer to a paleontologist. these ...ists baffles me LOL
John McCann
John McCann commented

This is ethology. The study of animal behavior in the wild. I was a Canid ethologist and studied Canis lupus arctos, the Arctic wolf, for much of my time in the field.

Paleontology is a subdivision of earth science. Geology, in other words.

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