Genetic Problems Worksheet
Solving without a Punnett Square
and Three Trait Problems
Genetics problems can be solved using probability in addition to Punnett Squares. Solving using
probability can be much more useful than Punnett Squares when solving for more than 2 traits.
1. List the number of possible gametes that could be formed from an individual who is Aa.
2. List the number of possible gametes that could be formed from an individual who is AaBb.
3. List the number of possible gametes that could be formed from an individual who is AaBbCc.
4. List the number of possible gametes that could be formed from an individual who is AaBbCcDd.
5. Do you notice a pattern on how the number of possibilities increases? What is that pattern?
6. What is a probability that an individual with the genotype of AaBb produces an “AB” gamete? Try
solving each trait individually (i.e. what is the probability that a gamete will have an A?) and then
combining those probabilities.
7. What is a probability that an individual with the genotype of AaBB produces an “AB” gamete? Try
solving each trait individually (i.e. what is the probability that a gamete will have an A?) and then
combining those probabilities.
8. If individual AaBb mates with individual AaBB, what is the probability that they produce an
offspring with the genotype AABB? Think about the gametes necessary to produce this offspring.
What is the probability of those gametes being made? Combine those probabilities.
9. Use a Punnett Square to check the previous problem after you have attempted to answer it using
probability.
10. What is a probability that an individual with the genotype of AaBbCc produces an “ABC” gamete?
Try solving each trait individually (i.e. what is the probability that a gamete will have an A?) and
then combining those probabilities.
11. What is a probability that an individual with the genotype of AaBBcc produces an “ABc” gamete?
Try solving each trait individually (i.e. what is the probability that a gamete will have an A?) and
then combining those probabilities.
12. If individual AaBbCc mates with individual AaBBcc, what is the probability that they produce an
offspring with the genotype AABBcc? Think about the gametes necessary to produce this
offspring. What is the probability of those gametes being made? Combine those probabilities