Note: these problems are significantly harder than the earlier set.
Do not worry if you cannot do them immediately. We will do some
similar examples in class.
FOR FRIDAY 10/23, LOOK AT SOME OF THESE EXAMPLES AND THINK ABOUT THEM!!
1. In a population of pea plants, the frequency of the tall (T) height allele is 0.8 and the frequency of the short (t) height allele is 0.2. What is the probability that a plant will be TT; Tt; tt?
2.In a population of pea plants, the frequency of the red-flower color allele is 0.7 and the frequency of the white flower-color allele is 0.3. What is the probability that a pea plant will have red flowers; white flowers?
3. A pea plant with red flowers and known genotype Rr, is bred to a pea plant
with red flowers and unknown genotype. Assume the allele frequencies are
as in problem 2.
(a) What is the probability that the plant of unknown genotype is RR; Rr; rr?
(b) What is the probability that this plant will pass on an R allele; an r
allele?
(c) What is the probability that these plants will have an offspring that is
RR; Rr; rr?
(See the example of the ND mother, and non-albino father; this is the same)
4. Repeat the same problem as above, only this time both parents have red
flowers with unknown genotypes.
(Again see the worked example.)
5. Again, repeat the same process, only this time one parent has white flowers, and the other parent has red flowers with unknown genotype.
6. For the ABO blood types, the frequency of the A allele is 0.3, of the B
allele is 0.1, and of the O allele is 0.6.
What is the probability that a person will be AA, AB, BB, AO, BO, OO?
7. Using the same allele frequencies as in problem 6:
(a) A person of blood type AB, and a person of blood type A but with an
unknown genotype, have a child. What is the probability that the child is
AA, AB, BB, AO, BO, OO?
(b) These same parents have a child with blood type A. What is the
probability that this child is AA, AO?
(c) If the child is AO, what is the probability that the parent of blood type
A is AA, AO?
8. Using the same allele frequencies as in problems 6 and 7:
Two parents of blood type B but unknown genotype have a child. What is
the probability that the child is BB; BO; OO? What is the probability
that this child has blood type B?
9. For the deafness gene Dfna1, the frequency of the autosomal dominant deafness allele is 0.01, and of the normal allele is 0.99. What is the probability that a person will be deaf; not deaf? (This probability only pertains to this deafness gene, not to any other causes of deafness that exist.)
10. For the Cf gene, the allellic frequency of the normal allele is 0.975 and of the mutant allele is 0.025. What is the probability that a person will be phenotypically normal? Will be a carrier? Will have Cf? What percent of phenotypically normal people will be carriers?
11. A woman, who is a carrier for the mutant Cf allele, marries a man of
normal phenotype but unknown genotype. Using the same allele
frequencies as above:
(a) What is the probability that their child will be phenotypically normal?
(b) What is the probability that their child will be a carrier?
(c) What is the probability that their child will have Cf?
12. Two people, who are phenotypically normal but have unknown genotypes,
marry and have a child. Using the cystic fibrosis allele frequencies from
above:
(a) What is the probability that their child has Cf?
(b) What is the probability that their normal child is a carrier?
(c) What is the probability that their normal child is not a carrier?