In a cross between two heterozygotes Dede Ctct X Dede Ctct w

In a cross between two heterozygotes (Dede Ctct X Dede Ctct), we can ask the following question: what is the probability that an offspring will have normal ears and a normal tail or have droopy ears and a crinkly tail? Do a punnet square to reval this:

Solution

Step 1

Calculate the individual probabilities of each phenotype

This can be accomplished using a Punnet square

The probability of normal ears and normal tail is

9 / ( 9+3+3+1) = 9/16

The probability of droopy ears and crinkly tail is

1 / (9+3+3+1) = 1/16

Step 2

Add together the individuals probabilities

1/16 + 9/16 = 10/16

This means that 10/16 is the probability that an offspring will have either normal ears and normla tail or droopy ears and a crinkly tail
this also is

10/16 = 0.625 , that means that 62.5% of the offspring are predicted to have a normal ears and a normal tail or have droopy ears and a crinkly tail