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Heterozygous/homozygous clarity
Yeah, I think that's just a typo. 3:1 ratio is seen for a Het x Het cross, and heterozygous, by definition, means that the two alleles are different (i.e. one dominant, one recessive).

On the other hand, a heterozygous x homozygous recessive cross would give a 1:1 ratio of dominant:recessive phenotypes.

Heterozygous/homozygous clarity
In the genetic practice problems attached to the lab manual, page A35 under "General logic" #4 says: "For example, a 3:1 ratio would imply that a heterozygous individual was crossed with a heterozygous RECESSIVE individual."

Is there such thing as a heterozygous RECESSIVE individual? Why can't it be a heterozygous dominant individual? Wouldn't that yield the same 3:1 ratio?

Genetics problems
Has everyone been trying the genetics practice problems? Any hang-ups? Post your questions here.

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Welcome
Welcome to the for Section 104.104!
Please feel free to post and answer questions in the discussion section, or to clarify any previous answers.