Genetics Problems
(single trait crosses)

Pictured above is an alien who displays all of the dominant characteristics of its species.  Below is a chart listing various traits found in this alien race.  Use the information in the chart to solve the genetics problems that follow.

Trait Dominant Phenotype Recessive Phenotype
Body color  (Y)  Yellow  (y)  Orange 
# of Antennae (A)  (a) 
Eye color (P)  Purple  (p)  White 
Eyesight (E)  Glasses needed  (e)  Glasses not worn
# of Body Rings  (R)  3 (r)  5

 

1.  A heterozygous male mates with a pure yellow female.  What is the chance this couple will produce an orange baby?  answer

2.  Two purple-eyed aliens mate.  Both aliens are hybrid for the eye color trait.  What is the chance this couple will produce a baby with a homozygous recessive genotype?  answer

3.  A heterozygous female with 3 body rings mates with a 5-ringed male.  What is the chance that this couple will have a baby that looks like its mother?   answer

4.  A pure male alien displaying the dominant body color mates with a female that is homozygous recessive for this characteristic.  What is the chance that this couple will have a baby with a hybrid genotype?  answer

5.  A male alien with 1 antenna mates with a female alien who has 2 antennae.  The female is heterozygous for the antenna trait.  What is the chance that this couple will produce a baby with the recessive phenotype?  answer

6.  An alien couple, both of which wear glasses, are having a baby.  The male's genotype is heterozygous.  The female is phenotypically dominant but does carry the recessive allele.  What is the chance that this couple's baby will have to wear glasses?  answer

7.  A 3-ringed female mates with a homozygous male.  The female has been genetically tested and is carrying both the dominant and the recessive allele for this trait.  The male displays the recessive phenotype.  What is the chance that this couple will have a genetically pure baby? answer

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Answers

 

1.  male = Yy     female = YY

     chance of orange baby (yy) = 0%

return to the problems

 

 

 

 

 

 

 

 

 

 

2.  male = Pp     female = Pp

     chance of baby with homozygous recessive genotype (pp) = 25%

return to the problems

 

 

 

 

 

 

 

 

 

 

 

3.  male = rr                  female = Rr

     chance of baby looking like mom - e.g. having 3 rings (RR or Rr) = 50%

return to the problems

 

 

 

 

 

 

 

 

 

 

4.  male = YY                  female = yy

     chance of baby having hybrid gentotype (Yy) = 100%

return to the problems

 

 

 

 

 

 

 

 

 

 

 

5.  male = aa     female = Aa

     chance of baby with recessive phenotype - e.g. 1 antenna (aa) = 50%

return to the problems

 

 

 

 

 

 

 

 

 

 

6.  male = Ee     female = Ee

     chance of baby wearing glasses (EE or Ee) = 75%

return to the problems

 

 

 

 

 

 

 

7.  male = rr     female = Rr

     chance of genetically pure baby  (RR or rr) = 50%

     return to the problems