Question

For the following crosses, indicate the probability of obtaining the indicated genotype in an offspring. Remember, it is easiest to treat each gene separately as a monohybrid cross and then combine the probabilities.

1. Cross: AABb × AaBb
Offspring: Aabb
2. Cross: AaBb × AaBb
Offspring: aaBB
3. Cross: AABbcc × aabbCC
Offspring: AaBbCc
4. Cross: AaBbCc × AaBbcc
Offspring: aabbcc

Answer 1

Answer:

1. Frequency of Aabb= 1/8

2. Frequency of aaBB= 1/16

3. Frequency of  AaBbCc = 1/2

4. Frequency of aabbcc = 1/32

Explanation:

1. Cross: AABb × AaBb

Offspring: Aabb

AA x Aa= 1/2 AA: 1/2 Aa

Bb x Bb = 1/4 BB: 1/2 Bb: 1/4 bb

Frequency of Aabb= 1/2 Aa x 1/4 bb= 1/8

2. Cross: AaBb × AaBb

Offspring: aaBB

Aa x Aa= 1/4 Aa: 1/2 Aa: 1/4 aa

Bb x Bb = 1/4 BB: 1/2 Bb: 1/4 bb

Frequency of aaBB= 1/4 aa x 1/4 BB= 1/16

3. Cross: AABbcc × aabbCC

Offspring: AaBbCc

AA x aa = All Aa

Bb x bb = 1/2 Bb : 1/2 bb

cc x CC = All Cc

Frequency of  AaBbCc  = 1 Aa x 1/2 Bb: 1 Cc = 1/2

4. Cross: AaBbCc × AaBbcc

Offspring: aabbcc

Aa x Aa= 1/4 Aa: 1/2 Aa: 1/4 aa

Bb x Bb = 1/4 BB: 1/2 Bb: 1/4 bb

Cc x cc = 1/2 Cc: 1/2 cc

Frequency of aabbcc = 1/4 aa x 1/4 bb x 1/2 cc= 1/32