Genetics question

[Opejay]

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In the dihybrid cross between AABb and AaBb, what fraction of the offspring will be homozygous dominant for A and homozygous recessive for B?

Help.

Thanks!

 

[fluoropHore]

You can make a large dihybrid cross like this http://www.biology.arizona.edu/mendelian_genetics/problem_sets/dihybrid_cross/graphics/03td.gif or compute the individual probabilities for each allele (AA vs Aa and Bb vs. Bb) and multiply. You should get 2/16...or 1/8

 

[sdm33]

Cross AA x Aa you will get 1/2 AA
Cross Bb x Bb you get 1/4 BB
1/2 x1/4 = 1/8 or 2/16 same def