Tue Breeding Dihybrid Cross for F2 generation

Question

5) A true breeding short tailed black eyed male was mated true breeding long tailed blue eyed female. Their offspring were taken and mated to make f2 generation.

 

3,000 long tailed black eyed males

1,200 long tailed blue eyed males

1,200 short tailed blue eyed males

3,000 short tailed black eyed males

10,000 short tailed blue eyed females.

 

Which tale length is dominant

What color is dom

What tail length is dom

What is mod of inheritance for tail length

Mode of inheritance for eye color

What is the geno and pheno for f1 female and f1 male.

Answer 1

Here is some help with how to approach this problem...

 

The first thing that we need to realize is that we are working with a dihybrid cross.  The traits we are working with are tail length and eye color.  The f1 generation will be heterozygous for both traits since we are crossing true breeding parents.  If simple inheritance is controling the trait we expect 4 phenotypes and  phenotypic ratio of the f2 generation to be 9:3:3:1.   Do the results we are given fit the 9:3:3:1 ratio?  

 

long/black __________

long/blue _________

short/black _________

short/blue __________

 

If it appears that this could fit the 9:3:3:1 ratio, we must conduct a chi^2 test to determine if we can statistically accept it.

 

If we can accept it then we can easily determine which tratits are dominant and which are recessive.