BIOL/PBIO 3333
Genetics
Quiz 2
22 February 2013
For Quiz Answers, click here
1. Manx cats are a large domestic breed that have very large hind haunches and a
shortened tail. When two Manx cats are crossed, 1/3 of the progeny do not show the
Manx phenotype- they have a normal body and tail. This finding is consistent with
which of the following?
a) the Manx characteristic behaves like a single gene trait, and all Manx cats are
heterozygotes for the Manx gene; b) the Manx tail phenotype is dominant; c) the
Manx gene acts as a recessive lethal; d) all of the above; e) none of the above.
2. Two pink-flowered snapdragon plants are crossed to each other. What is the
probability that in a group of six plants, there will be two pink, two whites and two
reds (Hint: remember the equation for solving specific terms of the binomial
expansion? How would this apply to the three phenotypes seen here?)
a) 0.0293; b) 0.088; c) 0.178; d) 0.352; e) none of the above.
3. In the common daisy, the genes A and a and B and b represent two pairs of alleles
acting on flower color. A and B are required for color. What would be the predicted
ratio of colored to colorless among the progeny of an F1 cross, where the parentals
were two colorless plants, one homozygous for A and the other homozygous for B
a) 9:3:3:1; b) 9:7; c) 9:3:4; d) 12: 3: 1; e) none of the above.
4. In corn, three dominant genes are necessary for aleurone color. The genotype
B_D_R_ is colored. Any homozygous recessive for one gene is colorless. The ratio of
colored to colorless individuals in the cross BbDdRr  BbDdRr would be:
a) 9:7; b) 16:1; c) 13:3; d) 27:37; e) none of the above.
Questions 5-7 pertain to the following. In Drosophila, a cross was made between
females expressing three X linked traits, scute bristles (sc) sable body (s) and
vermilion eyes (v), and wild type males. The F1 females were then crossed to wild
type males with the following results from 2000 progeny counted:
Females:
Males:
All wild type:
1000 progeny
Scute sable vermilion
Sable vermilion
Scute vermilion
Vermilion
Sable
Scute sable
Scute
Wild type
290
149
30
10
46
14
157
304
5. The distance between the scute and vermilion genes is:
a) 5 map units; b) 10 map units; c) 16.5 map units; d) 33 map units; e) 43 map units.
6. In this cross, the interference value is:
a) zero; b) 0.10; c) 0.27; d) 0.35; e) 0.73.
7. A scute male is crossed to a sable, vermilion female and the female progeny from
this cross are now crossed to scute sable vermilion males. Out of 1500 testcross
progeny produced, what number would be expected to be vermilion in phenotype?
a) 75; b) 150; c) 230; d) 247; e) none of the above.
Question 8 pertains to the following. The father of Mr. Spock, first officer of the
starship Enterprise, came from the planet Vulcan. Spock’s mother came from Earth.
A Vulcan has pointed ears (determined by allele P), adrenals absent (determined by
A) and a right-sided heart (determined by R). All are dominant to the normal Earth
alleles. The three loci are autosomal, and they are linked as shown in the following
linkage map:
A-------------------------10 m.u.---------------P--------------------8 m. u. -----------R
8. Assume Dr. Spock marries an earth woman. What proportion of their offspring
would have Vulcan ears and a right-handed heart, but with adrenals?
a) 3.6%; b) 4.6% c) 8%; d) 10%; e) 41.4%.
Questions 9 and 10 pertain to the
following. In Neurospora the cross
between AB x ab was made and 100
asci were scored with the results
shown on the right
9. In this cross, the distance between the
A locus and the centromere can be
estimated to be:
a) 7 map units; b) 14 map units; c) 22
map units; d) about 44 map units; d) the
A and B genes are not linked.
10. True or false. The distance between the A and B genes is over 32 map units.