## keepitsimple Group Title How many different phenotypes are possible in the offspring of two parents with genotypes AA and aa, where A is the dominant allele for a trait and a is the recessive allele for the same trait? one year ago one year ago

1. nincompoop Group Title

use a punnett square

"Phenotype" can be another word for "look," like the way an organism appears, physically. Let's pretend we're talking about flowers, that a capital A stands for RED flowers, and a lowercase a stands for WHITE flowers. RED and WHITE are two different phenotypes. Two different "looks." You get it? ~~~~~~~~~ Now, the question gives us two genotypes. (A A) is the genotype of one of the parents. (a a) is the genotype of the other parent. Let's pretend we're still talking about flowers. The (A A) parent would be a RED flower. And the (a a) parent would be a WHITE flower. We need to figure out the possible genotypes of their offspring. So, like nincompoop says, we need to make a Punnett Square. Here it is: |dw:1356761066854:dw| This Punnett Square has four squares in all. You see? Each of those four squares has a genotype that the offspring could have. And you see how all of the squares have the same genotype? (A a) What that means is that if a (A A) parent mates with an (a a) parent, then the offspring will always have the genotype (A a). So, since capital A represents RED flowers, and lowercase a represents WHITE flowers, what color would an (A a) genotype flower be? The answer is RED. Why? Because in the genotype, the capital letter always matters more than the lowercase letter. If there's a capital letter in the genotype, then that's the only one that matters. Again, if an (A A) parent mates with an (a a) parent, then there is a 100% chance that their offspring will have the genotype (A a). So, how many phenotypes could the offspring have? How many different "looks" could the offspring have?

3. nincompoop Group Title

I'll read on intro to Mendelian Genetics first. Let me know if you need the chapter text

4. keepitsimple Group Title

Thxs

Do you know the answer to the question? I could double check it with you.

6. abb0t Group Title

Oh gawd no.

Guys, abb0t doesn't approve. Everything in this threat is now invalid. abb0t gets a medal.

8. realsofia Group Title

4

@realsofia 1. I would have preferred to see our friend keepitsimple figure out the answer for him/herself. It encourages the learning process. 2. You're wrong.

10. realsofia Group Title

okay so then what is the answer then?