In Dachshunds black is dominate, chocolate is recessive, shorthair is dominate over longhair.

What would be the genotypes and phenotypes if you cross a hetrozygous black shorthair dachshund with a hetrozygous black shorthair dachshund?

1. The first thing that we need to do is set up a interpretation key.
   
   BB or Bb = black, bb = chocolate , XX or Xx = shorthair, xx = longhair
   
   
2. Next you write out the cross.
   
   

   BbXx crossed with BbXx

   
   
   
3. Then you number the first set of genes from the cross.

4. 1	2	3	4
   B	b	Y	y

   
   
   
5. The next thing you need to do is determine the possible gene combinations.
   
   

   Pair #1 with #3, #1 with #4, #2 with #3, and #2 with #4

   1-3	BY
   1-4	By
   2-3	bY
   2-4	by

   Place in square in top of the columns.

   
   
   
6. Repeat step 4 with the second set of genes in the cross. Place in square in front of the rows
   
   
   
   
7. So you end up with a square like this.
   
   

   	BY	By	bY	by
   BY
   By
   bY
   by

   
   
   
8. We take the letters at the top of each column and place it in each square below.

   	BY	By	b  Y	by
   BY	B  Y	B  y	b  Y	b  y
   By	B  Y	B  y	b  Y	b  y
   bY	B  Y	B  y	b  Y	b  y
   by	B  Y	B  y	b  Y	b  y

   
   
   
9. We take the letters at the front of each row and place it in each square next to it.
   
   

   	BY	By	b  Y	by
   BY	BB  YY	BB  Y y	Bt  Y Y	Bt  Y y
   By	BB  Yy	BB yy	Bt  Yy	Bt  yy
   bY	Bt  Y Y	Bt  Y y	bb  Y Y	tt  Y y
   by	Bb  Yy	Bb  yy	bt  Yy	bt  yy

   
   
   
10. Now we determine the genotypes and the phenotypes.

    Ratio	Genotype	Phenotype
    1/16	BBXX	black, shorthair
    1/16	BBxx	black, longhair
    2/16	BBXx	black, shorthair
    2/16	BtXX	black, shorthair
    4/16	BbXx	black, shorthair
    2/16	Bbxx	black, longhair
    2/16	bbXx	chocolate, shorthair
    1/16	bbXX	chocolate, shorthair
    1/16	bbxx	chocolate, longhair

    
    
    
11. Summary 9/16 black shorthair, 3/16 black longhair, 3/16 chocolate shorthair, 1/16 chocolate longhair.