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BIOLOGY 350
GENETICS
EXAM 2
NAME_______________
1. (15pts) Name all of the Hardy Weinberg equilibrium assumptions (okay, there are
8).
2. (15pts) Genes a, b, and c are recessive. Females heterozygous at these three loci
are crossed to phenotypically wild-type males. The progeny are phenotypically as
shown.
a. (5pts) What is known of the female’s parents genotype with respect to
these three loci? Give the gene order and arrangement of the homologs.
b. (10pts) Map the three genes
Daughters:
All
+++
Sons
TOTAL
+++
23
abc
++c
ab+
+bc
a++
a+c
+b+
26
45
54
427
424
1
0
1000
3. (10pts) Define narrow sense heritability and provide the equation for determining
it.
4. (10pts) A quantitative geneticist determines that for leaf width in a wild flower:
VA= 4.2, VD = 1.6, VE = 2.7 What is the narrow sense heritability for leaf width?
Show your work in setting up your answer
Unknown to many people, there are three loci in tomatoes that cause these insidious
plants to bear fruit of very large size. The ordinary tomato weighs a pound. When
homozygous for contributing alleles at all three loci, however, the plant bears “killer
tomatoes” weighing 301 lbs. Assume each locus contributes equally to the fruit size
and answer the following questions (Questions 5, 6, 7, and 8)
5. How much in fruit weight does each contributing allele contribute?
a. 300lb
b. 200lb
c. 100lb
d. 50lb
e. 1 lb
6. If one crosses a normal tomato with a killer tomato plant, F 1 plants producing 150
lb fruits are formed. How frequently will a plant producing 200lb tomatoes be found
among the F2 progeny?( 150lb F1 plants selfed)?
a. 1/64
b. 6/64
c. 15/64
d. 20/64
e. none of these
7. Suppose a 150 lb F1 plant is test crossed with an ordinary (1 lb) tomato. How
frequently will a tomato plant bearing 100lb tomatoes be produced?
a. 1/4
b. 3/8
c. 1/3
d. 1/64
e. 15/64
8.What is the weight of a tomato with the following genotype: AaBbCC?
a. 51 lbs
b. 101 lbs
c. 151 lbs
d. 201 lbs
e. 251 lbs
Population Genetics:
For Questions 9 - 13, let A and a represent dominant and recessive alleles
whose respective frequencies are p and q in a given interbreeding
population at equilibrium (p + q = 1).
9. If 16 percent of the individuals in the population have recessive phenotypes, what
is the percentage of heterozygous genotypes?
a. 24%
b. 48%
c. 68%
d. 88%
e. none of these
10. If 16 percent of the individuals in the population have recessive phenotypes,
what percentage of the TOTAL number of recessive genes exist in the heterozygous
condition?
a. 20%
b. 40 %
c. 60%
d. 80%
e. none of these
11. Red green color blindness is due to a sex linked recessive gene. About 64
women out of 10,000 are color blind. What proportion of men would be expected to
show the trait if mating is random?
a. 8%
b. 18%
c. 28%
d. 48 %
e. 68%
12. A sample population in West Virginia show that 152 residents had type M blood
(IM IM), while 259 had type MN blood (IM IN), and 89 had type N blood (IN IN). What is
the frequency of the type M allele (IM) in this population?
a. 0.563
b. 0.304
c. 0.551
d. 0.422
e. none of these
13. In a large endangered tiger population 60 percent of individuals have begun
inbreeding. The frequency of the recessive allele a is 0.02.What will its frequency be
after two generations of inbreeding at this rate?
a. 0.02
b. 0.315
c. 0.56
d. 0
e. none of these
14. Which of the following is likely to have the most dramatic effect on allele
frequencies in a founding population of 12 individuals over 2 generations.
a. mutation
b. migration
c. genetic drift
d. inbreeding
Bonus:
What year was Mendel’s work published?
a. 1565
b. 1665
c. 1765
d. 1865
e. 1905