BIOL/PBIO 3333
Genetics
Quiz 2
9/27/14
For the answers to the quiz, click here:
Question 1 pertains to the following. In the guinea pig, one locus involved in the control of coat color may
be occupied by any of four alleles: C (full color); ck (sepia); cd (cream); or ca (albino). The order of
dominance is C > ck > cd > ca.
1. A sepia guinea pig was crossed to cream guinea pig. The sepia guinea pig had an albino parent and the
cream guinea pig had a sepia parent and an albino parent. What would be the phenotypes and the ratios of
the progeny produced in this cross?
a) 1 sepia: 1 cream; b) 3 sepia: 1 cream; c) 1 sepia: 2 cream: 1 albino; d) 3 cream: 1 albino; e) none of the
above.
2. Considering the ABO blood types in humans, identify the genotypes that would be expected for the two
parents depicted below:
Male parent: Blood type A: father type B
Female parent: Blood type B: mother type O
Which of these blood types would be possible among the offspring of this couple?
a) type A; b) type AB; c) type O; d) all of the above; e) only two of the above are correct.
3. Horses can be cremello (a light cream color) chestnut (a brownish color) or palomino (a golden color
with white in the tail). Of these phenotypes, only palominos never breed true. The following phenotypes
and ratios were observed in several crosses:
Cremello x palomino
1 cremello: 1 palomino
Chestnut x palomino
1 chestnut: 1 palomino
Palomino x palomino
1 chestnut: 2 palomino: 1 cremello
These results are most consistent with:
a) recessive lethality; b) incomplete dominance; c) recessive epistasis; d) complementary gene action; e)
none of the above.
4. In a species in the cat family, eye color can be gray, blue, green or brown, and each trait is truebreeding. In separate crosses involving homozygous parents, the following were observed:
Cross
1
2
3
P1
Green x gray
Green x brown
Gray x brown
F1
All green
All green
All green
F2
3 green: 1 gray
3 green: 1 brown
9 green: 3 brown: 3
gray: 1 blue
In a cross between a gray-eyed cat and one of unknown genotype, the F1 generation was not observed.
However, the F2 resulted in the same F2 ratio as cross 2. The genotypes of the original parents (P1
generation) can be represented as:
a) AA x aa; b) AAbb x aaBB; c) AAbb x AABB; d) AA′ x Aa; e) AaBb x Aa
Questions 5-6 pertain to the following: In hobbits, the recessive genes for nonhairy feet (f), allergy to pipe-weed (p) and poor appetite (a) are all recessive to
the wild type alleles. Females heterozygous for all three genes were mated to
males homozygous recessive for all traits. The phenotypes of the recovered
progeny are given in the table on the right:
5. The distance, in map units, between the f and a loci is:
a) 19.7 m.u. b) 21 m.u. ; c) 22.6 m.u.; d) 39.4 m.u.; e) these genes are not
linked.
phenotype
apf
a++
ap+
+++
+p+
++f
+pf
a+f
number of
progeny
21
90
293
15
82
313
94
92
6. The coefficient of coincidence for this experiment is:
a) 0.005; b) 0.036; c) 0.25; d) 0.625; e) 0.78.
Questions 7-8 pertain to the following. A trihybrid corn plant is testcrossed.
The progeny phenotypes and frequencies are in the table on the right:
7. The map distance between the b locus and the c locus is:
a) 3.5 map units; b) 7.1 map units; c) 45.8 map units; d) 46.7 map units; e) the
two genes show no evidence of linkage.
8. The map distance between the a locus and the c locus is:
a) 3.5 map units; b) 7.1 map units; c) 45.8 map units; d) 46.7 map units; e) the
two genes show no evidence of linkage.
phenotype
+++
+bc
++c
abc
a++
ab+
a+c
+b+
number of
progeny
455
33
37
470
35
37
456
477
Questions 9 and 10 pertain to the following. Neurospora fungi of genotype a+ were crossed to a mating
type that contained the mutant +b alleles for these two gene loci. In the chart below, 1000 individuals are
scored for spore genotype distribution:
Spore
number
1
2
3
4
5
6
7
8
totals
-------------------------------------------------Ascus Types------------------------------------------
1
2
3
4
5
6
7
++
++
ab
ab
+b
+b
a+
a+
5
++
++
ab
ab
++
++
ab
ab
1
+b
+b
ab
ab
++
++
a+
a+
5
a+
a+
a+
a+
+b
+b
+b
+b
808
+b
+b
a+
a+
+b
+b
a+
a+
90
++
++
++
++
ab
ab
ab
ab
1
++
++
+b
+b
a+
a+
ab
ab
90
9. The distance between the a gene and the centromere is approximately:
a) 5.05 map units; b) 10.1 map units; c) 9.3 map units; d) 19.2 map units; e) none of the above.
10. The distance between the a and b genes is approximately:
a) 1.2 map units; b) 5.2 map units; c) 10.25 map units; d) 20.5 map units; e) the a and b genes are not
linked.