Zoo/Bot 3333
Genetics
Quiz 2
February 25, 2011
For answers to the quiz, click here
1. A gene influencing canary color has two alleles. A yellow male canary is crossed to a
green female canary. In their progeny, all the females are yellow and all the males are
green. Considering the mechanism of sex determination for this species, which of the
following are true?
a) this gene locus is sex-linked; b) green feather color is dominant to yellow; c) a cross
between two F1 siblings will produce equal numbers of green and yellow males; d) all of
the above; e) none of the above.
2. In the guinea pig, an allelic series is involved in coat color, where C (full color) >ck
(sepia) > cd (cream) > ca (albino). If a sepia and cream guinea pig are crossed, and both of
these guinea pigs had an albino parent, what would be the expected phenotypes and ratio
observed in the offspring of this sepia x cream cross?
a) 3 sepia: 1 albino; b) 3 cream: 1 albino; c) 1 cream: 1 albino; d) 9 full: 3 cream: 3 sepia:
1 albino; e) none of the above.
Questions 3-4 pertain to the following. In cats, eye color can be grey, blue, green or
brown, and each trait can be true-breeding. In separate crosses between true-breeding
strains, the following results were obtained:
Cross
Parental
F1
F2
1
Green x gray
Green ¾ green: ¼ gray
2
Green x brown Green ¾ green: ¼ brown
3
Gray x brown Green 9/16 green: 3/16 brown 3/16: gray: 1/16 blue
3 True or false: Since we see a 3:1 ratio in the phenotypes detected in the F2 crosses,
these four colors must represent allelic variants at a single gene locus that have difference
dominance relationships.
4. From the above results, what result would be expected in the F2 generation in a cross
between a true-breeding blue and a true-breeding green cat?
a) the same results as cross #1; b) the same results as cross #2; c) the same results as
cross #3; d) ½ blue: ½ green; e) none of the above.
5. With regard to the ABO locus, a male parent has blood type B; his mother was type A.
The female parent has blood type A; her father was type B. Which of the following
possibilities are excluded?
a) children of blood type A; b) children of blood type B; c) children of blood type AB; d)
children of blood type O; e) all classes would be expected to be produced in equal
frequencies.
Questions 6-7 pertain to the following cross. A fly heterozygous for three different genes
(AaBbCc) is testcrossed to a fly homozygous
Phenotype Number of progeny
recessive for these three mutations. The following
Abc
18
progeny types are produced and given in the table
aBc
630
on the right:
abc
148
6. The distance between the a and c locus is:
AB c
132
a) 8 map units; b) 9 map units; c) 16 map units; d)
a BC
22
17.9 map units; e) the a and c genes are not linked
abC
120
in this cross.
ABC
140
AbC
615
7. The coefficient of coincidence for the above
total
1825
cross is:
a) 0.0288; b) 0.193; c) 0.762; d) 1.31; e) none of the above is correct.
8. A fly heterozygous for three different genes
(AaBbCc) is testcrossed to a fly homozygous recessive
for these three mutations. The following progeny types
are produced and given on the table on the right:
Which of the following are correct?
a) The B gene locus is not linked to the A gene locus;
b) the distance between the B and C gene loci is 8 map
units; c) in the parental heterozygote, the B and C loci
are in the trans configuration; d) all of the above; e)
none of the above.
Phenotype Number of progeny
abC
228
aBc
235
aBC
16
abc
22
AbC
224
ABc
233
ABC
22
Abc
20
total
1000
Questions 9 and 10 pertain to the following. A cross in Neurospora was conducted
between two different mating types carrying different alleles for genes A and B. The
cross could be represented as aB x Ab. The following classes of asci were obtained:
Spore
pairs
total
1
Ab
Ab
aB
aB
127
2
AB
AB
ab
ab
125
3
Ab
AB
ab
aB
100
4
Ab
ab
AB
aB
36
5
Ab
aB
Ab
aB
2
6
AB
ab
AB
ab
4
7
AB
ab
Ab
aB
6
9. The distance between the A gene locus and the centromere is:
a) 6 map units; b) 12 map units; c) 14 map units; d) 18.5 map units; e) 28 map units.
10. The distance between the A gene locus and the B gene locus is:
a) 6 map units; b) 8 map units; c) 20 map units; d) 40 map units; e) the two genes are not
linked.