Name ____________
Probability and Punnett Square Practice Set
Per. _______
This worksheet is meant to have you test your skills at the ye olde punnett square and to help hone you
probability skills to make your math teacher happy.
We’ll start off with some easy ones.
1. Green (GG) pea color is dominant to Yellow (gg) Pea color. If you breed two plants one Green the of yellow
what would you get?
2. Red Hair (rr) in humans is recessive to all other hair colors (Rr). If you bred a red headed father with a
auburn haired mother, what genotypic ratio would you get?
Genotypic ratio: ______ : ______
3. Simple Math Problems:
a. ¼ + ¼ = _____
b. ½ ÷ ½ = _____
c. ¼ × ¼ = _____
Time for some harder ones.
4. Fill in the Punnett Square for this DiHybrid Cross.
You have decided to break into the Guinea Pig breeding business, and want to corner the market on straight
haired (g) blue(w) Guinea Pigs. Both traits require a homozygous recessive (ggww) and are true-breeding. You
have two completely heterozygous guinea pigs (GgWw). Use the punnett square to find out the likelihood
(probability) of getting a completely recessive guinea pig.
Time for some harder probability math problems (WOO FRACTIONS)
6.
a. ¾ - ½ = ____
b. ¼ × ¾ = ____
c. 5/8 ÷ ¼ = _____
Now for the really hard question (TRIHYBRID):
7. Having made a fair bit of business on your straight haired blue Guinea Pigs, you have decided to branch out.
You’d like to start selling both long and short haired versions of your blue Guinea Pig. Short hair in guinea pigs
is a Dominant trait so is denoted with (H). How many blue, straight long haired guinea pigs can you expect to
be able to bring to market if your breeders predict 64 baby Guineas being born? (ggwwHh x ggwwHh)
AND NOW FOR SOME PROBLEMS THAT FORK LINE METHOD IS GOOD FOR.
1. In the cross between the following parents: AaBb x AaBB – what is the chance that the offspring’s
genotype will be AABB?
2. The following parents are crossed:
NnMMkkLl x nnMmKKLl
How many offspring will have the dominant phenotype for the N and K genes?
3. In seahorses the Z gene codes for zebra stripes which are dominant over no stripes. The X gene codes
for crossed eyes which is dominant over uncrossed eyes. Lastly, the J gene codes for jelly fish like
tentacles which are dominant over (jj) squidlike tentacles. You have two parents that are completely
heterozygous for all traits. Can they have offspring that have Zebra Stripes, uncrossed eyes, and
squidlike tentacles? If so, what is the percent chance that this would happen? (Hint: # / 64)
4. THE TOUGH ONE:
While visiting China, you managed to acquire a breeding pair of pandas. The pandas have some unique
traits that you think could be used to start a business. The female panda has green eyes (bb), black fur
splotches (Ff), and white body fir (Ww) while the male panda has black eyes (Bb), white fur splotches
(ff), and green body fir (ww). The shady person that sold you the pandas say that they carry the gene for
domestication (d) but are not domesticated. Your goal is to breed the pandas in hopes of getting a panda
with the following phenotype: Black Eyes, Black Splotches, Green body fir, and domestication AKA the
EC PANDA! Based on the information above, what is the percentage of chance that the offspring of the
breeding pair of pandas will be EC Pandas?
5. Genotype to Phenotype interpretation:
Blue (B) = Dominant
Hairy (H) = Dominant
Three legs (T ) = Dominant
Round eyes (R) = Dominant
Head Spikes (S) = Dominant
Triangle Head (G) = Dominant
Red (b) = Recessive
bald (h) = Recessive
Two Legs (t) = Recessive
Diamond eyes (r) = Recessive
Head Loops (s) = Recessive
Pentagon Head (g) = Recessive
Draw the phenotype that represents this genotype: BbHhttrrSsgg
Draw the phenotype that represents this genotype: bbHHTtRRssGg
6. Using the traits from the above question, what would the offspring look like from the following parents:
bbhhttrrssgg x BBHHTTRRSSGG ? (list the traits)