Download Organism # of Gamete # of Zygote # of Pairs of Zygote

Name:
Date:
Period:
Genetics - Exercises and Problems
Meiosis and Genetics
Adopted from the University of Virginia's Biology Department
I.
Complete the following table:
Organism
# of Gamete
Chromosomes
Ascaris Suis
A. Megalocephala
Drosophilia
Melanozaster
Onion
Pig
Corn
Human
Crayfish
I
# of Zygote
Chromosomes
4
2
8
# of Pairs of Zygote
Chromosomes
4
8
19
10
9.
Assuming that in any of the organisms mentioned in I, all members of paired chromosomes differ
from each other. Which ~ese
organisms could theoretically produce the greatest variety in its
offspring? From you own observations, which of these organisms actually show the greatest
variety?
'(
Monohybrid Cross:
10. Let A be any dominant gene and a be its corresponding recessive gene. Assuming that each pair
of parents has 32 offSrring, give thj ;xpected genotype results of the following crosses.
AAxAA)AAxAa\AAxaa
Aa x A'f'a x a~aaxaa
II. In Holstein cattle solid color is dominant over spotted coat. Ifa homoz\iygous solid colored bull is
mated to a spotted cow for 12 breeding seasons, what would be the nature ofthe expected
offspring, both phenotypically and genotypically? What results would be expected if both bull
and cow were heterozygous? What results would be expected if a spotted bull was mated with 8
heterozygous cow? (Let S stand for a solid color; s for spotted)
12. Determine the probably genotype of the parents in Holstein cattle for each ofthe following groups
of offspring:
200
2.
A given organism has two pairs of chromosomes in diploid cells. This is represented by the
formula AA8B. A stands for one kind of chromosome and B for the other. Using these letters,
how would you represent a gamete?
3.
In the organism described in #2, assume that you can distinguish one of the A chromosomes from
the other a, and one of the B chromosomes from the other b; you may represent the diploid cell as
AaBb. (independent assortment)
a. How many distinguishable kinds of gametes could be formed from such diploid cells?
b. Using the symbols A, a, B, and b, show the chromosome content of all possible kinds of
haploid cells. '
.
a.
b.
c.
d.
e.
f.
Offspring
Offspring
Offspring
Offspring
Offspring
Offspring
all spotted
9 solid, 2 spotted
6 solid, 6 spotted
all solid, (3 possible answers)
7 solid, 5 spotted
II solid, I spotted
~I'
4.
5.
v.
Assume that you can distinguish the chromosomes AaBbCc in a diploid cell. (independent
assortment)
3.
How many kinds of gametes might result from meiosis?
b. Show the chromosome content of all possible gametes.
Repeat what you have done in #4, with the additional pair, Dd.
••• ..,u"•••..••,'-'••.."...•
I~"
Diploid Cell
VI..J,
•..•
•.••
....•..•...•.•...•....•......••....••..•.....•
vn .
# of kinds of gametes
# of kinds of gametes expressed
as a power of2
AaBb
AaBbCc
AaBbCcDd
7.
From the results of the above table, state a general rule for determining the number of kinds of
gametes when you know the diploid number of chromosomes.
\
8.
Using the general rule formulated in 7, give the number of kinds of gametes for all ofthe
organisms mentioned in # l.
'"
Offspring 10 ~
2
j
Sf.VlltJ
50 '(;1
13. A blue-eyed child has a brown-eyed father and a brown-eyed mother. From this family would you
-judge that blue eyes are the result of a dominant Or a recessive gene? Why or why not?
14. In cats the gene for short hair is dominant over the gene for long hair (Angora). A short-haired
tom cat is mated with an Angora female. She has a litter of 8 kittens, 6 short-haired and 2 with
long hair. If you mated these same cats 4 more times, getting a total of 40 offspring, would you
expect the results to be closer to the expected ratio? What was the genotype of the torn cat?
15. Anoather short-haired tom cat, mated several times with an Angora, results in nurn/erous
offspring all of which are short-haired. If you wished to produce Angora kittens, how would you
go about it if you are to select parents from among all these kittens and their parents?
16. The polled (hornless) condition in cattle is dominant over horned. A cattle man has the range
stocked with polled cattle only, but some horned cattle occasionally appear in the offspring. These
are removed from the range before they can reproduce. It is assumed that the range is fenced and
that stray bulls are kept out. How do you explain the occurrence of homed offspring?
17. In summer squash white fruit color is dominant over yellow. If a squash plant homozygous for
white is crossed with one homozygous for yellow, what will be the APPEARANCE of the F,? Of
the F,? Of the offspring ofa cross of the F, back to its yellow parent? (backcross)
18. A white fruited squash plant when crossed with a yellow fruited one produces offspring about half
of which are white and half yellow. What are the genotypes of the parents? (Let W represent the
gene for white, w the gene for yellow.)
19. A certain polled bull (see 16, above) is bred to 3 cows. With cOWA, which is homed, a polled calf
is born; with cOWB, also horned, a horned calfl$produced; with cow C, which is polled, a horned
calf is produced. What are the genotypes of these 4 animals, and what further offspring would you
expect from these 3 matings? (Let P represent the gene for polled, p the gene for homed.)
~\e..
20. In man, brown eyes, B, are dominant over blue, b. A brown-eyed man has 8 children with a
woman with blue-eyes that are all brown-eyed. What are the GENOTYPES of all the individuals
in this family? PHENOTYPES?
32. If you toss an unbiased coin and an unbiased'lq at the same time, what is the probability that you
will get heads and 3? ("Note: the probability of2 unrelated events is equal to the probability of
one multiplied by the probability of the other.)
21. A blue-eyed man both of whose parents were brown-eyed
father was brown-eyed and whose mother was blue-eyed.
What are the genotypes of all the individuals mentioned?
33. Jfyou draw two cards, one after the other, from a perfectly shuffled deck, what is the probability
of getting a pair of aces?
married a brown-eyed woman whose
They have one child, who is blue-eyed.
22. In guinea pigs the coat may be rough or smooth. Certain rough-coated guinea pigs when crossed
with smooth coated guinea pigs produce all rough coated guinea pigs. Other rough-coated guinea
pigs when crossed with smooth coated ones produce equal numbers of tough coated and smoothe
coated guinea pigs. Smooth coated animals when crossed together always produce offspring
whose coats are smooth. Explain these results. Write the genotypes for all the animals concerned
in these crosses.
Lack of Dominance
23. In 4:00 flowers, red flower color, J:is not completely dominant over white, R', the heterozygous
plants being pink colored. In the following crosses, in which the genotypes of the parents are
given, what are the gametes produced by each parent, and what will be the flower color of the
offspring from each cross?
RR'l<RI,R'R'xRR'
RRxR'R'
,RR'xRR'
I
24. If you wanted to produce 4:00 seed all of which would yield pink-flowered
how would you do it?
plants when sown,
25. ln Andalusian fowls the heterozygous condition of the alleles for black plumage B, and white
plumage, B', is blue. What offspring will" blue Andalusian fowl have if bred to birds of the
following plumage?
a.
b.
c.
Black ~
Bluet
White?
26. In shorthorn cattle red coat, R, is incompletely dominant over white coat, R', the heterozygous
condition being a mixture of red and white hairs, called roan. A cattleman has a roan bull and
some white cows, but wants a pure-breeding red herd on his ranch. Outline a breeding program
for him to follow which will enable him to do this without bringing in other stock.
27. In snapdragons the homozygous condition (RR) results in red flower color; (RR') the
heterozygous condition results in pink flower color; and the homozygous recessive (R'R') results
in white flower color. If a red plant is crossed with a white plant, what will be the phenotype and
genotype of the F, plants" If you cross two of the F, plants what will be the resulting phenotypes
and genotypes of the F, plants?
Probability
28. If you toss a coin which is unbiased (i.e. just as likely to faU one way as the other), what is the
probability that it will show heads rather than tails?
29. In a toss ofan unbiased die (pI. dice) what is the probability
4,5, or 6?
34. If you toss die A and die B at the same time, what is the probability that you will get a 5 and a 6?
This problem differs from any of the above, in that there are 2 ways of getting 5 and 6. If A turns
up 5, then B must turn up 6 to get this combination; if A turns up 6 then B must turn up 5. ('Note:
If a type of event may occur in several mutually exclusive ways, the probability of the type is the
sum of the probabilities of the different ways. Hence, in the above problem the probability of A
turning up 5 and B turning of 6 is 116 x 116 or 1/36; the probability of A turning up 6 and B
turning up 5 is also 1/6 x 1/6 or 1/36. Thus the probability of 5 and 6 turning up either way is 1136
+ 1136 or 1/18.)
35. If you toss 2 coins at the same time, what is the probability that you will get two heads? Two tails?
One head and one tail?
1/i'-.O~
36. Give male gametes half of which contain gene A and half gene j, and female gametes half of ,
which contain gene A and half gene.t~at
is the probability after fertilization occurs that zygote
AA will be formed? aa? Aa? (Note that this is determinable by the product and the sum rules of
probability.)
37. Assuming brown eyes to be dominant and blue eyes recessive, what is the probability
offspring of two heterozygous brown-eyed parents will have
a.
b.
that an
Brown eyes?
Blue eyes?
Dihybrid cross
38. What are the gametes formed by the following squash plants, the genotypes of which for fruit
color and shape are given? Assume that white fruit W is dominant over yellow w; and disk fruit
shape D, is dominant over sphere shape, d.
a. WWdd x wwDD
b. WwDd x Wwdd
c. WwDD x wwdd
d. WwDd x wwdd
39. What will be the appearance of the offspring from each cross in #38?
40. A white disk squash crossed with a yellow sphere squash results in a seed which when planted
yields the following:
a.
b.
c.
d.
37
33
33
35
White, disk
white, sphere
yellow, disk
yellow, sphere.
that it will turn up I, rather than 2, 3,
30. What is the probability that you will turn up the 7 of diamonds in cutting a perfectly shuffled pack
of cards (52 cards in a pack of cards)?
31. What is the probability that you will turn up any 7 in cutting a perfectly shuffled pack of cards?
What were the genotypes of the parents?
41. Some dogs bark when trailing, others are silent. The barking trait is due to a dominant gene (B)
and silent trait is due to a recessive gene (bb). Erect ears (E) are dominant to drooping ears (ee).
What kind of pups would be expected from a heterozygous, erect eared mated to a droop-eared,
silent trailer?
42. Albinism in humans is due to a recessive gene, the allele of which results in normal pigmentation.
In very few humans, a condition known as wooly hair is due to a dominant gene. located on
another chromosome. A wooly-haired albino, on Iy one of whose parents was wooly haired,
marries a straight-haired woman whose father was a homozygous normally pigmented man and
whose mother was
albino. What is the probability that a child of theirs will be
a. Wooly haired?
b. Albino?
c. Wooly haired and albino?
d. Straight haired and normally pigmented
an
Sex-Linked Inheritance
43. A color blind man has a child with a woman with oormal vision. From this union ooe color-blind
daughter is born. Give the genotypes of these three people. List the genotypes and phenotypes of
all possible offspring from this pregnancy?
44. A male with normal vision has a child with a female with normal vision whose father also has
normal vision. They produce a colorblind boy. From which of his four grandparents did this child
derive the gene fro colorblindness?
45. A man sues his wife for divorce on the grounds of infidelity. Both the man and his wife have
normal vision, but there is a daughter who has a defect of the eye which is known to be a sex~inked recessive. Is this sufficient evidence of infidelity on the part of the wife? Why or why not?
46.
A certain recessive lethal gene in man is carried On the X-Chromosome, but not on the Y
chromosome. An individual who fails to receive at least one does of the dominant allele dies
before birth. In a mating between a normal male and a heterozygous female show the expected
sex ratio of living births.
Inheritance of Blood Types
47. Give genotypic and phenotypic ratios of the offspring of the following parents:
a. AB x 00
b. AOxBO
c. ABxAB
d. AB xBO
e. AAxAB
48. Four babies were born at the hospital the same night. Their blood groups were later found to be 0,
A, Band AB. The 4 pairs of parents were
I. 0 and 0
2. AB and 0
3. A and B
4. Band 8
How could each of the babies be assigned to its right parents?
49. A woman with blood types A, M has a child with types B, MN. Her husband has types A, Nand
accuses a certain man of being the father of the child. The man is found to have types B, N. Does
this evidence offer conclusive proof of the paternity of the child?
50. After 8 years ofpartnered life, during which time she had frequent relations with her husband, but
had failed to become pregnant, Mrs. X fell in love with Mr. Y. During the 5 years which followed,
2 children were born. In the meantime, the persons involved tried to come to an understanding
and wished to determine which of the 2 men was the father of each child. The blood types of
these involved were:
a.
b.
Husband
Lover
O,MN
A,N
c.
d.
e.
f.
Wife
I" Child
2" Child
3" child
What conclusions
O,MN
O,MN
O,M
A,N
can be made as to the father of each child?
51. Mrs. J becomes pregnant once a year. Her first 3 children are completely normal and b0"l without
mishap. The 4" child is definitely jaundiced, but survives. The 5th child dies ofjawldic)ll shortly
after birth. The 6", 7" and 8· conceptions end in abortion. The 9" child is normal and born
without mishap. Assume that the Rh gene is involved. Give the genotype of Mrs. J, Mr. J and all
of the children. Indicating any uncertainties and reasons therefore.
52. A woman of blood type 0 has a child of type B; the mother accuses Mr. X, who is type AB of
being the father is this sufficieot proof?