Exam 1-Practice Q's

Question 1

How many chromosomes are in a chromosome sets in a grasshopper

if n=12

Answer 1

12

Question 2

How many chromosome sets are present in a diploid somatic cell of an individual grasshopper?

Answer 2

2

Question 3

The cattle, Bos taurus, is a diploid organism with a haploid chromosome number of 30. How many total chromosomes should be present in a germ cell of a cattle in prophase II of meiosis?

Answer 3

30

Question 4

If a somatic cell in a diploid dog has 78 total chromosomes how many total chromosomes would you expect to in that dog’s gametes?

Answer 4

n=39

Question 5

Which if the following statements about homologous chromosomes is true?

a) They have identical DNA sequences
b) There are a pair of homologous chromosomes in each haploid gamete
c) They contain all of the same genes but not necessarily the same alleles
d) homologous chromosome pairs pair up and undergo crossing over during anaphase I of meiosis

Answer 5

c) They contain all of the same genes but not necessarily the same alleles

Question 6

Draw a diagram of a germ cell of an organism with a diploid chromosome number of 6 in metaphase I of meiosis. In your diagram label a pair of homologous chromosomes and a pair of sister chromatids

Answer 6

answer in quiz 1

Question 7

Which of Mendel’s two laws of inheritance apply only to pea plants and not to other organisms?

a. ) Mendel’s law of segregation
b. ) Mendel’s law of independent assortment
c. ) Both the laws of segregation and independent assortment apply organisms that reproduce sexually
d. )Both the laws of segregation and independent assortment apply only to pea plants, because that was all Mendel studied

Answer 7

c.) Both the laws of segregation and independent assortment apply organisms that reproduce sexually

Question 8

In a particular type of flowering plant, purple
petals are dominant to white petals, and flat leaves are dominant to curly leaves. If a plant that was heterozygous for both traits was crossed with another plant that was also heterozygous for both traits, what is the probability that an offspring would be heterozygous for both traits?

Answer 8

1/4 that the offspring would be heterozygous for both traits WwCc

Question 9

In a cross between AaBbCc and AaBbCc, what is the probability that an offspring will be AaBbCc?

Answer 9

1/21/21/2=1/8

Question 10

A test cross is designed to determine the genotype of a parent plant with the dominant tall phenotype. All of the resulting offspring are tall. What is the genotype of the tall parent?

Answer 10

DD

Question 11

A man with albinism, a recessive trait, and a woman with a normal phenotype have several children, one of which displays albinism

a) What is the genotype of the mother with the normal phenotype
b) What is the probability that the children that do not display albinism are heterozygous

Answer 11

a) heterozygous

b) 100%

Question 12

Mendel crossed pea plants that had purple, axial flowers with plants that had white, terminal flowers, and all the F1offspring had purple, axial flowers. He then allowed the F1offspring to self-fertilize, and he examined 575F2offspring. The following were his results: 318purple, axial; 108purple, terminal; 110white, axial; 39white, terminal. Are these results consistent with the hypothesis that the gene that determines flower color assorts independently from the gene that determines flower position in pea plants

Answer 12

observed: 318/575 WT, 108/575 Wt, 110/575 wT, 39/575 wt
expected: 323/ 575, 108/575, 108/575, 36/575

chi square = 0.06608
p= 0.995 fail to reject

Yes the results are consistent with the hypothesis of independent assortment

Question 13

The haploid chromosome number of the house mouse, Mus musculus, is 20. What is the total number of chromosomes expected in the diploid body cells of a mouse

Answer 13

40

Question 14

The diploid number of an organism is 20

a) How many homologous pairs of chromosomes are present in a germ cell in prophase I
b) How many chromosomes would be present in prophase II?

Answer 14

a) 10

b) 10

Question 15

Two highly inbred strains of mice, one with black fur and the other with gray fur were crossed (you can assume each strain is true-breeding). All of the F1 offspring had black fur. Predict the genotypic outcome of intercrossing the F1 offspring

Answer 15

1 GG: 2 Gg: 1 gg

Question 16

Predict the phenotypic outcome of intercrossing the F1 offspring

Answer 16

3 black: 1 gray

Question 17

What is the probability of flipping a penny, a nickel, a dime and a quarter and getting heads on each flip

Answer 17

1/21/21/2*1/2=1/16

Question 18

What is the probability that you will roll a 1 or a 3 on a dice?

Answer 18

1/6+1/6=2/6

Question 19

Q: In a cross between 2 heterozygotes (Aa), what is the probability that the offspring will be homozygous recessive (aa)

Answer 19

1/2*1/2=1/4

Question 20

In a cross between 2 heterozygotes (Aa), what is the probability that an offspring will be a heterozygote

Answer 20

There are 2 mutually exclusive ways in which a heterozygote Aacan be produced from 2 heterozygous parent
Aa : 1/2*1/2= 1/4
or 
aA: 1/2*1/2=1/4
1/4+1/4 = 1/2

Question 21

A cross between a homozygous white feathered rooster and a homozygous black feathered hen results in black and white spotted heterozygous chicks. What is the most likely explanation of inheritance of feathers in chickens

Answer 21

codominance

Question 22

In a Mendelian monohybrid cross involving codominant alleles, which of the following statements is true?

Answer 22

Offspring would exhibit a 1:2:1 genotypic and phenotypic ratio

Question 23

Hemophilia is a blood clotting disorder in humans that follows an X-linked recessive pattern of inheritance. A man with hemophilia and a woman without hemophilia have a daughter with hemophilia. What are the genotypes of the parents? Use XH to represent the normal allele and Xh to represent the hemophilia allele.

Answer 23

Mother is X^HX^h and father is X^hY

Question 24

The following interactions are found in mice. The albino allele (b) eliminates all color in homozygotes and is recessive to the normal pigment allele (B). The black allele (a) causes the normal gray-brown agouti coat color to be much darker and is recessive to the normal agouti allele (A). A mouse with the genotype aaBb will be what color

Answer 24

have a black coat

Question 25

Anhidrotic ectodermal dysplasia is an X-linked recessive disorder in humans characterized by small teeth, no sweat glands, and sparse body hair. This trait is usually seen in men, but women who are heterozygous carriers of the trait often have irregular patches of skin with few or no sweat glands, and the distribution of such patches differs among affected heterozygous females, even between identical twins.

a) Explain why heterozygous women have irregular patches of skin lacking sweat glands.
b. ) Why does the distribution of skin patches lacking sweat glands differ among affected heterozygous female

Answer 25

a) women have 2 X chromosomes, making them more likely to express the recessive gene
b) x inactivation is random so it expresses in some places but not in others

Question 26

A mutation that causes a yellowing of leaves in snapdragon plants was discovered in the early 1900s. Plants with this condition are called aurea and have less chlorophyll than green plants. Crosses between various combinations of green and aurea plants yielded the following results.
green x green = all green
aurea x aurea = 2/3 aurea, 1/3 green
green x aurea = ½ green, ½ aurea

a) How can you explain the unusual results from these crosses?
(b) With respect to snapdragon color, what can be said about the Gand G^A alleles?

Answer 26

a) area is a recessive lethal allele

b) aurea is dominant with respect to color

Question 27

Assume that long ear lobes in humans are an autosomal dominant trait that exhibits 30% penetrance. A person who is heterozygous for long ear lobes mates with a person who is homozygous for normal ear lobes. What is the probability that their first child will have long ear lobes

Answer 27

Long x normal
Llxll
(1/2 chance it will be ll) = 0.5 chance
30% penetrance = 0.3 chance

0.5x 0.3= 15% chance

Question 28

The wild-type fur of mice is described as agouti, which results from a light band of pigment on a dark hair shaft. A true-breeding mouse with agouti fur was crossed with a true-breeding albino mouse (with white fur), and all the F1 mice were agouti. The F1 mice were intercrossed, and the F2 progeny were as follows: 43 agouti, 16 black, 20 albino
a ) Explain these results (i.e. genetic phenomenon)

(b) What are the genotypes of the true-breeding agouti mouse, the true-breeding albino mouse, and the F1agouti mice

Answer 28

ratio is 43/79 = 9 
16/79 = 3
20/79 = 4
9:3:4
a) recessive epistasis 
b) agouti- BBAA
albino- bbaa
black- bbAA

Question 29

The haploid chromosome number of the house mouse Mus musculus, a diploid organism, is 20. If the cells of an individual mouse all have a total of 39 chromosomes, which of the following terms correctly describes those cells

a) diploid
b) trisomic
c) polyploid
d) monosomic

Answer 29

d) monosomic

Question 30

Which of these following terms best describes those cells?

a) euploid
b) polyploid
c) aneuploid
d) tetraploid

Answer 30

c) aneuploid

Question 31

Male Drosophila do not undergo crossing over. When doing a testcross in flies to determine recombination frequency, which sex must the tester parent (the homozygous recessive)

Answer 31

male

Question 32

Two genes that are 60 map units apart are expected to show \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
A. independent assortment
B.25 percent recombination
C.30 percent recombination
D.50 percent recombination
E.60 percent recombination

Answer 32

A. independent assortment

Question 33

Two recessive mutant alleles in tomato plants, m (mottled) and d(dwarf), affect leaf type and plant height. Two true-breeding tomato plants were crossed, resulting in wildtype F1 dihybrids with normal leaves and tall height. An F1 plant was then crossed with a homozygous recessive (mottled, dwarf) plant, and the F2 generation included the following phenotypes and numbers:
55 wildtype
8 dwarf
53 mottled, dwarf
7 mottled
(a) Calculate the frequency of recombination between the two genes
(b)Was the F1 double heterozygote in cis or trans?(c)What were the genotypes of the true-breeding parent

Answer 33

(a) 12%
d and m are recombinant together they make up 12%

(b) cis
draw both combinations

(c) MD/ MD and md/md

Question 34

If you cross a true-breeding black cat with a true-breeding white cat and allof the offspring are black and white spotted, what type of inheritance is demonstrated

Answer 34

codominance

Question 35

Two black dogs are crossed, resulting in a ratio of 2/3 black to 1/3 white dogs in the offspring, with equal numbers of male and female offspring with each phenotypic class. Which genetic inheritance pattern can explain these result

Answer 35

the black allele is lethal

Question 36

Marfan syndrome is an autosomal dominant disorder associated with a mutation in collagen that results in skeletal, optical, and cardiovascular abnormalities. Any individual with a dominant mutant allele exhibits at least one of the symptoms, with varying degrees of severity. This is an example of which genetic phenomenon

Answer 36

variable expressivity

Question 37

The haploid chromosome number of the Jimson weed is 12(n= 12). Which of the following terms should not be used to describe a Jimson weed plant with four sets of chromosomes (48 total chromosomes)?

a. polyploid
b. aneuploid
c. euploid
d. tetraploi

Answer 37

aneuploid

Question 38

The diploid chromosome number in fruit flies is 8 (2n= 8). How many total chromosomes would be found in the following types of flies?

a. Trisomy 2
b. monosomy 4
c. 3n

Answer 38

a. 9
b. 7
c. 12