How do I determine the genotypic ratios that may appear among the progeny of simple crosses?

Question

How about the genotypes of the parent's that may give rise to each ratio?

I am very confused. I have a chart that I'm supposed to fill out, one the left colum it has a genotypic ratio of 1:2:1 and right under that it has 1:1. Then it says, uniform progeny (all offspring look the same). On the right side it says, parental genotypes, and the three bars next to each of the above is empty.

What the heck?

Will someone please give me a clue as to how I should solve this?

Answer 1

it is difficult from info you give~to suggest an answer~in life there are so many variables.

recessive genes

dominant genes

s*x linked genes

would suggest ~on web ~"bbc gcse bitsize genes"

"bbc science and nature"~for site links.

a good guide ~if you have access to a library ~have a look in the pet section .

there are some guides to genetics~try "new coloured canaries.

hope this helps

have a nice day

Answer 2

Can you send me that chart? ([e-mail]) and I'll try to resolve it.

Now, try to do it yourself following next tips:

P1: AA    x    BB

G1: A   A    B    B

F1: AB, AB, AB, AB

P2: AB    x    AB

G2: A   B    A   B

F2: AA, AB, BA, BB     (comment: AB and BA are the same!!! so you have F2: AA, 2AB, BB - *1:2:1*)

P3: AA    x     AB

G3: A   A    A   B

F3: AA, AB, AA, AB <=> 2AA, 2AB <=> 2:2 <=> *1:1*

This is basic:

P: AB     x     CD            <=     REMEMBER THIS!!!

G: A   B    C    D            <=     REMEMBER THIS!!!

F: AC, AD, BC, BD      <=     REMEMBER THIS!!!