Kevin J Grundig vetech at
Wed Nov 13 05:47:42 EST 1996

Test Quiz For Genetics buffs:
Results are for Genetics class
Send Answers to email: grundigk at
Thanks for your input.

1.) In Drosophila, kidney-shaped eye (k), cardinal eye (cd), and ebony
body (e) are three recessive genes.  If homozygous kidney, cardinal
females are crossed with homozygous ebony males, the Fl offspring are
all wild-typ
e. If heterozygous Fl females are mated with kidney, cardinal, ebony,
males, the following progeny appear:

880 kidney, cardinal
887 ebony
64 kidney, ebony
67 cardinal
49 kidney
46 ebony, cardinal
3 kidney, ebony, cardinal
4 wild-type

Calculate the distances between the three genes, and draw a map of the
chromosome on which they are located.  (5 points)

2.) The following three recessive markers are known in lab mice:
hotfoot (h), obese (o), and waved (wa).  A mouse heterozygous for all
three traits was testcrossed, with the following results:

357 hotfoot, obese, waved 
74 hotfoot, obese
66 waved
79 obese
343 wild-type
61 hotfoot, waved
11 obese waved
9 hotfoot

Determine the relative order and map distance between the genes
involved.  (5 points)
Calculate Interference, if any exists.  (2 points)
What are the phenotypes of the parents of the triply heterozygous
mouse?  (2 points)

3.) In university administrators, the following genes responsible for
character mutations have been localized to chromosome 20: brainless
(bl), intolerant (mt), and arrogant (ar). The distances between these
genes are as 

bl-int 10.0 map units 
int-ar 6.1 map units
bl-ar 16.1 map units

Construct a map of chromosome 20 based on these data.  (2 points)

Calculate the probability of a double crossover between the genes
involved. (2 points)

4.) In corn, the alleles C and c result in colored versus colorless
seeds, Wx and wx in nonwaxy versus waxy endosperm, Sh and sh in plump
versus shrunken endosperm.  When plants grown from seeds heterozygous
for each of t
hese pairs of alleles were testcrossed with plants from colorless,
waxy, shrunken seeds, the progeny seeds were as follows:

4 colorless, nonwaxy, shrunken
974 colorless, nonwaxy, plump
20 colorless, waxy, shrunken
2349 colorless, waxy, plump
951 colored, waxy, shrunken
99 colored, waxy, plump
2216 colored, nonwaxy, shrunken
15 colored, nonwaxy, plump

Determine the relative order of the three genes and construct a linkage
map showing the distances between the genes.  (5 points)

5.) In Drosophila, the genes ct (cut wing margin), y (yellow body), and
v (vermilion eye color) are X-linked.  Females heterozygous for all
three traits were mated with wild-type males, and the following male
offspring we
re obtained:
(Remember + means wild-type allele for that gene)

	ct	y	v	4
	ct	y	+	93
	ct	+	v	54
	ct	+	+	349
	+	y	v	331
	+	y	+	66
	+	+	v	97
	+	+	+	6

What is the order of the genes?  (2 points)
Calculate the recombination frequencies and the interference between
the genes.  (5 points)
Draw a genetic map of the x chromosome showing the relative positions
of these genes  (1 point)
Why were only male offspring counted?  (2 points)

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