Midterms and Sample Final Exam Flashcards Preview

BIOL 2500 > Midterms and Sample Final Exam > Flashcards

Flashcards in Midterms and Sample Final Exam Deck (98):
1

This cell is from a diploid mammal. Which stages of cell division are possible? The cell shows 4 chromatids being pulled by the mitotic spindle to each pole of the cell.
A) Anaphase I
B) Anaphase II
C) Anaphase of mitosis
D) a & c
E) b & c

E) b & c

2

Which of the following statements is (are) true?
A) Once meiosis is complete, further cell division always requires fertilization and formation of a zygote
B) Homologous chromosomes first pair in metaphase I
C) Cytokinesis occurs during both telophase I and II
D) All of the above
E) b and c only

C) Cytokinesis occurs during both telophase I and II

3

Which feature(s) of cell division generate(s) new combinations of alleles even in the absence of mutation?
A) Formation of sister chromatids
B) Independent assortment of chromosomes
C) Crossing over
D) a and b
E) b and c

E) b and c

4

Cells from a normal diploid plant have 16 chromatids in G2 of the cell cycle. All the pollen mother cells in one pant experience non-disjunction in meiosis I. How many chromosomes would occur in the gametes (pollen grains) produced by this plant?
A) 3,4, or 5
B) 7,8, or 9
C) 3 or 5
D) 7 or 9

C) 3 or 5

5

Potential causes of trisomy 21 (most common aneuploidy in humans) discussed in class include _____.
A) maternal age
B) smoking
C) low socio-economic status
D) all of the above
E) a and b

D) all of the above

6

In Phlox, blue flowers are dominant to white flowers. If two heterozygotes are crossed, what is the expected ratio of phenotypes in the offspring?
A) 1 blue: 1 white
B) 3 blue: 1 white
C) 1 white : 3 blue
D) all white
E) all blue

B) 3 blue: 1 white

7

Mendel crossed Y/Y;R/R (yellow, round) peas with y/y;r/r (green, wrinkled) peas. The F1 were all yellow and round. The F1 were selfed to generate the F2. What proportion of the offspring would be green and round?
A) 1/16
B) 3/16
C) 1/3
D) 1/9
E) 9/16

B) 3/16

8

Mendel crossed Y/Y;R/R (yellow, round) peas with y/y;r/r (green, wrinkled) peas. The F1 were all yellow and round. The F1 were selfed to generate the F2. What proportion of the offspring would be green and round? In the above cross, what proportion of the offspring would be heterozygous at one or both loci?
A) 3/4
B) 3/8
C) 1/8
D) 1/4
E) 1/2

A) 3/4

9

The presence or absence of dimples is controlled by a single autosomal gene with complete dominance. John and Nasreen always prided themselves on their dimples and they are a little surprised when their first child has none. What is the probability that 3 of their next 5 children will also be without dimples?
A) 0.016
B) 0.088
C) 0.176
D) 0.264
E) 0.422

B) 0.088

10

You are breeding Babbitts and paying attention to 4 traits, each controlled by a single independently asserting gene with 2 alleles and complete dominance. You cross a male with black hair that is silky, round ears, and a calm temperament (genotype is: B/b; S/S; R/r; c/c) with a female with brown hair that is woolly, round ears, and aggressive temperament (genotype is: b/b; s/s; R/r; C/c). What is the probability that the first offspring will be your desired phenotype of black silky hair, round ears and a calm temperament?
A) 1/16
B) 3/16
C) 9/32
D) 27/64

B) 3/16

11

In peas, tall plants are dominant to short plants, and purple flowers are dominant to white flowers. A tall plant with white flowers was crossed to a short plant with purple flowers. The offspring had the following phenotypic ratio:
1 tall, white : 1 tall, purple : 1 short, white : 1 short, purple
What are the genotypes of the parents?
A) Ttpp * ttPP
B) TtPp * ttpp
C) TTPP * ttpp
D) Ttpp * ttPp
E) Ttpp * TTPp

D) Ttpp * ttPp

12

Red-green colour blindness in humans is recessive and X-linked. A woman with normal vision whose father was colour blind marries a man with normal vision whose father was also colour blind. What proportion of their offspring will be colourblind?
A) no females, all the males
B) no females, half the males
C) half the females, half the males
D) half the females, one quarter of the males

B) no females, half the males

13

What phenotypic gender would XO individual have in Drosophila and C. Elegans, assuming the normal number of autosomes?
A) D: male , C: male
B) D: male , C: hermaphrodite
C) D: female , C: hermaphrodite
D) D: female , C: male
E) D: intersex , C: male

A) D: male , C: male

14

Which of the following organisms were described in lecture as having environmental sex determination?
A) turtles
B) clownfish
C) Butterflies
D) a and b

D) a and b

15

In Drosophila experiment, a mutant gene causing white eyes is X-linked recessive and a mutant gene causing short bristles is autosomal recessive. Two parents from true breeding lines are crossed. One is a white eyed, long bristled male and the other is a red eyed, short bristled female. All the F1 have red eyes and long bristles. What proportion of the F2 males will have white eyes and long bristles?
A) 1/8
B)1/4
C) 1/2
D) 3/8
E) 0

D) 3/8

16

In birds, a dominant Z-linked gene, B, produces barred feathers, and the recessive allele, b, produces non-barred feathers. A large group of full siblings were scored for wing patterns. A half of the males and half of the females had barred feathers. How many copies of the B allele did each parent have?
A) female 1, male 1
B) female 2, male 1
C) female 0, male 1
D) female 1, male 0

C) female 0, male 1

17

You are studying ABO blood groups in human populations. If a man of type I^A I^B marries a woman of genotype I^A i, what proportion of their offspring will be heterozygous for blood type?
A) 0
B) 1/4
C) 1/2
D) 3/4

D) 3/4

18

The gene affecting coat colour in horses shows incomplete dominance. A cremello (cream) horse and a chestnut (brown) horse are crossed and their offspring are palomino (light brown). What ratio of phenotypes would you expect if a palomino horse mates with a chestnut horse?
A) 1 chestnut : 2 palomino : 1 cremello
B) 3 chestnut : 1 palomino
C) 1 chestnut : 1 palomino
D) 3 chestnut : 1 cremello

C) 1 chestnut : 1 palomino

19

You are studying the colour of wing bars in rock doves. A true breeding line with plum wing bars is crossed to a true breeding line with white wing bars. The F1 all have plum wing bars. In the F2 scores for wing bars are as follows: 898 plum : 297 blue : 403 whites. What does this ratio suggest about the inheritance of wing bars?
A) An interaction between two independently assorting loci affecting one trait
B) A new phenotype resulting from dominant allele(s) at either, but not both, of two independent loci
C) Dominant epistasis
D) Recessive epistasis

D) Recessive epistasis

20

In mice, dominant allele A results in pigmented hairs and allele a causes albino hairs (= no pigments, white appearance). A dominant allele at an independently assorting locus B, causes agouti pigment and allele b causes black pigment. What ratio of progeny would occur if a AaBb (agouti) mouse was mated to an albino aaBb mouse.
A) 9 agouti : 3 black : 4 white
B) 9 agouti : 6 black : 1 white
C) 3 agouti : 1 black : 4 white
D) 4 agouti : 8 black: 4 white

C) 3 agouti : 1 black : 4 white

21

You cross two field mice with the rare phenotype of short tails and get a 2:1 ratio of short to long tails. When you cross short and long tailed mice you get a 1:1 ratio of phenotypes. A second, independently assorting gene controls belly colour with white bellies (W) dominant to grey bellies (ww). If two Ww mice with short tails are crossed, what would be the probability of getting a mouse with a grey belly and a long tail?
A) 9/16
B) 3/16
C) 1/6
D) 1/12

D) 1/12

22

A high proportion of Olympic gold medalists are homozygous for the recessive ns (nerves of steel) trait. When present, this trait enhances performance under pressure by a consistent margin of 10%. Unfortunately, only half of individuals with the appropriate genotype exhibit the trait. This is an example of:
A) complete penetrance and variable expressivity
B) incomplete penetrance and constant expressivity
C) complete penetrance and constant expressivity
D) incomplete penetrance and variable expressivity

B) incomplete penetrance and constant expressivity

23

Genes that are linked _______.
A) segregate to opposite poles during meiosis
B) assort independently during meiosis
C) do not assort independently during meiosis
D) none of the above

C) do not assort independently during meiosis

24

In wild bluebells, linked genes determine flower colour and leaf shape. Blue flowers (B) are dominant to pink flowers (b), and long leaves (L) are dominant to round leaves (l). A double heterozygote is crossed to a plant with pink flowers and round leaves. 1000 offspring are raised and show the following phenotypes:
Blue flowers and round leaves - 435 plants
Blue flower and long leaves - 60 plants
Pink flowers and round leaves - 60 plants
Pink flowers and long leaves - 445 plants

The frequency of recombination between these two genes is ____ %.
A) 12
B) 6
C) 60
D) 8.8
E) 88

A) 12

25

In wild bluebells, linked genes determine flower colour and leaf shape. Blue flowers (B) are dominant to pink flowers (b), and long leaves (L) are dominant to round leaves (l). A double heterozygote is crossed to a plant with pink flowers and round leaves. 1000 offspring are raised and show the following phenotypes:
Blue flowers and round leaves - 435 plants
Blue flower and long leaves - 60 plants
Pink flowers and round leaves - 60 plants
Pink flowers and long leaves - 445 plants

For the above cross, what was the genotype of the double heterozygote?
A) Bl/bL
B) BL/bl
C) Bl/bl
D) You can’t tell from the information given

A) Bl/bL

26

You have obtained the genetic map below for four genes in Babbitt. Which pair(s) of genes are unlinked?

Genetic map: a-b-c-d
10 32 18
A) a-c and a-d
B) a-d only
C) b-d only
D) a-d and b-d
E) they are all linked

D) a-d and b-d

27

In a three point test cross, you observed a double crossover frequency of 0.20 between two genes for which you expected to see a double crossover frequency of 0.25. What were the Coefficient of Coincidence (COC) and the Interference?
A) COC=0.2, Interference=0.8
B) COC=0.8, Interference=0.2
C) COC=0.2, Interference=0.25
D) COC=0.25, Interference=0.2

B) COC=0.8, Interference=0.2

28

The following phenotypes are observed following a 3 point test cross of a heterozygous corn plant. What is the order of the genes involved?
++C = 174
A++ = 21
A+C = 3
+++ = 50
+B+ = 2
AB+ = 178
ABC = 48
+BC = 24
Total: 500

A) BCA
B) ABC
C) CAB

C) CAB

29

A diploid mammal cell shows 5 chromatids being pulled to opposite poles. What type of cell division is occurring?
A) meiosis II
B) mitosis
C) meiosis I
D) you can’t tell from this picture

A) meiosis II

30

Place the following events in the correct temporal sequence during growth and development in eukaryotes.
-condensation of chromosomes
-movement of chromosomes to the poles
-alignment of chromosomes in the middle of the cell
-re-formation of the nuclear envelope
-duplication of chromosomes
A) condensation, movement, alignment, duplication, envelope
B) duplication, condensation, alignment, movement, envelope
c) condensation, duplication, alignment, movement, envelope
D) envelope, condensation, alignment, movement, duplication

B) duplication, condensation, alignment, movement, envelope

31

If a mammalian gamete has 6 chromosomes, how many chromatids were present in a single cell at metaphase II?
A) 3
B) 6
C) 12
D) 24
E) 48

C) 12

32

Which of the following statements is (are) true?
A) Homologous chromosomes first pair in metaphase I.
B) Sister chromatids separate in anaphase of mitosis and anaphase II.
C) Once meiosis is complete, formation of a zygote must occur before any further cell division can take place
D) a and b only
E) b and c only

B) Sister chromatids separate in anaphase of mitosis and anaphase II.

33

Which phase of cell division relates to Mendel’s principle of independent assortment?
A) Meiosis I
B) Meiosis II
C) Mitosis
D) both a and b

A) Meiosis I

34

Purple and white flowered pea plants from true-breeding lines are crossed, and all F1 plants are purple. If an F1 plant is selfed, the expected ratio of purple: white in the progeny is?
A) 3 purple: 1 white
B) 1 purple: 1 white
C) 1 purple : 3 white
D) 1 purple : 0 white

A) 3 purple: 1 white

35

A dolphin with the autosomal recessive trait of albinism was recently born to two normal dolphins. If the same two dolphins mate again, what is the probability that three of their next five offspring will be normal?
A) 0.250
B) 0.264
C) 0.063
D) 0.088

B) 0.264

36

Mendel crossed Y/Y; R/R (yellow, round) peas with y/y; r/r (green, wrinkled) peas. The F1 were all yellow and round. The F1 were selfed to generate the F2. What proportion of the offspring would be yellow and wrinkled?
A) 1/16
B) 3/16
C) 5/16
D) 8/16
E) 10/16

B) 3/16

37

Mendel crossed Y/Y; R/R (yellow, round) peas with y/y; r/r (green, wrinkled) peas. The F1 were all yellow and round. The F1 were selfed to generate the F2. What proportion of the offspring would be heterozygous at one but not both loci?
A) 1/16
B) 3/16
C) 6/16
D) 8/16
E) 10/16

D) 8/16

38

What phenotypic gender would an XO individual have in Drosophila and C. Elegans assuming the normal number of autosomes?
A) D: male, C: male
B) D: male, C: hermaphrodite
C) D: female, C: hermaphrodite
D) D: female, C: male
E) D: intersex, C: male

A) D: male, C: male

39

In humans, brown eyes (B) are dominant to blue eyes (b), and the ability to dance (D) and wink (W) is dominant to the lack of ability (d and w). All these genes are autosomal and independently assorting. A woman of genotype bbDdww marries a man who is BbDdWw. What is the probability that their first child will be a girl and will exhibit the dominant phenotype for all three traits?
A) 3/16
B) 1/16
C) 1/32
D) 3/32

D) 3/32

40

In rabbits, a dominant allele (L) causes long hair and a recessive allele (l) causes short hair. At an independently assorting locus, a dominant allele causes black hair (B) and a recessive allele causes brown hair (b). A long haired, black rabbit from a true breeding line is crossed with a short-haired brown rabbit, and the F1 offspring are inter crossed. What proportion of the long haired brown F2 rabbits would not breed true?
A) 2/16
B) 3/16
C) 2/3
D) 1/3
E) 1/9

C) 2/3

41

A man with normal vision marries a woman with normal vision whose father was colour blind (x linked recessive). _____________ of their daughters will be ____________.
A) 1/2 carriers
B) 3/4 normal
C) 1/2 colour blind
D) all colour blind

A) 1/2 carriers

42

Horns in ungulates with sometimes sex influenced with the presence of horns being dominant in males and recessive in females. A large litter of goats show the following phenotypic ratios females: 3 hornless, 1 horned; males: 1 hornless, 3 horned What were the genotypes of the parents in this litter?
A) female: H+/H+ male: H+/H-
B) female: H+/H- male: H+/H-
C) female: H+/H- male: H-/H-
D) female: H-/H- male: H+/H+

B) female: H+/H- male: H+/H-

43

Which of the following statements abound sex chromosomes is/are true:
A) Sex chromosomes evolved multiple times during vertebrate evolution
B) Males always have degenerate sex chromosomes due to lack of recombination
C) Species with multiple sex chromosomes often produce inviable intersex gametes
D) Species without sex chromosomes are clonal or hermaphroditic
E) Statements A and B

A) Sex chromosomes evolved multiple times during vertebrate evolution

44

In chickens, the allele coding for black feathers (B) shows incomplete dominance to the allele coding for white feathers (b). If a bird with grey feathers is crossed with a bird with white feathers, the expected ratio of phenotypes in the offspring would be:
A) 1 black: 2 grey: 1 white
B) 3 grey: 1 white
C) 1 grey: 1 white
D) 1 black: 1 grey

C) 1 grey: 1 white

45

In a Drosophila experiment, two red eyed flies with long bristles are bred together and produce the offspring listed below:
Phenotype Females. Males
Red eyed, normal bristles 1/4. 1/8
Red eyed, long bristles 3/4. 3/8
White eyed, normal bristles. —. 1/8
White eyed, long bristles —. 3/8
Is the mutant gene for long bristles dominant or recessive? Is the mutant gene for long bristles sex-linked or autosomal?
A) recessive, sex-linked
B) recessive, autosomal
C) dominant, sex-linked
D) dominant, autosomal

D) dominant, autosomal

46

You are studying the colour of wing bars in rock doves. A true-breeding line with plum wing bars is crossed to a true breeding line with blue wing bars. The F1 all have plum wing bars. The colour of wing bars in the F2 is in the following ratio 167 plum: 44 blue: 12 white. What does this ratio suggest about the inheritance of wing bars?
A) recessive epistasis
B) dominant epistasis
C) an interaction between two independently assorting loci affecting one trait
D) a new phenotype resulting from dominant allele(s) at either, but not both, of two independent loci

B) dominant epistasis

47

In mice, dominant allele A results in pigmented hairs and allele a causes albino hairs (no pigment, white appearance). A dominant allele at an independently assorting locus, B, causes agouti pigment and allele b causes black pigment. What ratio of progeny would occur if an AaBb (agouti) mouse was mated to a black (Aabb) mouse?
A) 9 agouti: 3 black: 4 white
B) 9 agouti: 6 black: 1 white
C) 3 agouti: 1 black: 4 white
D) 3 agouti: 3 black: 2 white

D) 3 agouti: 3 black: 2 white

48

In rabbits, multiple alleles control coat colour with wild type grey allele (C+) dominant to both chinchilla (Cch). Chinchilla is dominant to white. What is the expected ratio of phenotypes for the following cross C+ Cw and Cch Cw?
A) 2 grey: 1 chinchilla: 1 white
B) 1 grey: 2 chinchilla: 1 white
C) 1 grey: 1 chinchilla
D) 3 grey: 1 white
E) all grey

A) 2 grey: 1 chinchilla: 1 white

49

Plasma cholesterol levels for individuals that are homozygous normal (++) range from 150-250 mg/do. Cholesterol levels in individuals that are heterozygous for the FH (familial hypercholesterolemia) allele range from 280-550. Cholesterol levels in individuals that are homozygous for the FH allele range from 600-1000? This is a good example of ______ and ________.
A) Codominance and variable expressivity
B) Codominance and variable penetrance
C) Incomplete dominance and variable expressivity
D) Incomplete dominance and variable penetrance

C) Incomplete dominance and variable expressivity

50

Which of the following statements about allergies is false according to material presented in lecture?
A) There is a genetic component to allergies.
B) There is an environmental component to allergies.
C) Specific genes have been linked to allergies.
D) The same allele may increase or decrease susceptibility to allergies, depending on the environment
E) The only possible way to avoid food allergies is to avoid risky foods until children are 3 years old

E) The only possible way to avoid food allergies is to avoid risky foods until children are 3 years old

51

In Drosophila, a gene influencing wing shape is 15 map units from a gene for eye colour. A fly that is heterozygous at these genes for mutant alleles causing vestigial wings and apricot eyes (++/vg ap) is test crossed. How many of the 1000 offspring should be recombinant?
A) 850
B) 425
C) 150
D) 75

C) 150

52

Two linked genes have alleles A and B in coupling (cis) in a double heterozygote. Which of the following genotypes for the offspring of a test cross would indicate that recombination had occurred between the two genes?
A) Ab/Ab
B) Ab/ab
C) AB/AB
D) AB/ab

B) Ab/ab

53

The following phenotypes are observed following a 3-point test cross of a heterozygous corn plant. What is the order of the genes involved?
++c = 21
a++ = 174
a+c = 3
+++ = 50
+b+ = 2
ab+ = 24
abc = 48
+bc = 178
Total = 500

A) acb
B) abc
C) cab

A) acb

54

The following phenotypes are observed following a 3-point test cross of a heterozygous corn plant.
++c = 21
a++ = 174
a+c = 3
+++ = 50
+b+ = 2
ab+ = 24
abc = 48
+bc = 178
Total = 500
Which pairwise distance in the above cross is the shortest?
A) ab
B) ac
C) bc
D) the distances are the same

C) bc

55

You have obtained the genetic map below for four genes in wild radish. What is the expected rate of double cross over between a and c?

a—-10—-b——-30————c———12——d

A) 0.40
B) 0.04
C) 0.30
D) 0.03
E) a and d are unlinked so it doesn’t matter

D) 0.03

56

In a three point test cross, the coefficient of coincidence measures,
A) the accuracy of map distances between all three genes
B) how comparable the numbers of complementary phenotypes are
C) the proportion of expected double cross-overs that are actually observed
D) whether the crossing data are reliable

C) the proportion of expected double cross-overs that are actually observed

57

Which type of cell division results in daughter cells that are identical to the original 2N cell (ignore mutation)?
A) meiosis II
B) mitosis
C) meiosis I
D) both a and b

B) mitosis

58

Two cells are from a diploid bird and are at the same stage of cell division. One 3 chromatids of the same size being pulled to opposite poles, and the other cell has 2 big chromatids and 1 small chromatid being pulled to opposite poles. They are from a ______ undergoing _________ .
A) male, anaphase I
B) male, anaphase II
C) female, anaphase I
D) female, anaphase II

D) female, anaphase II

59

If a mammalian gamete has 8 chromosomes, how many chromatids were present in the adult cell in G2 of interphase?
A) 64
B) 32
C) 8
D) 16

B) 32

60

Who would have the longest telomeres?
A) a newborn infant
B) an Olympic athlete
C) a grandmother

A) a newborn infant

61

Non-disjunction in mitosis II would result in?
A) 50% aneuploid gametes
B) 25% normal gametes
C) 50% gametes with an extra chromosome
D) 25% gametes missing a chromosome
E) both a and d

E) both a and d

62

Tall and short pea plants from two true-breeding lines are crossed, and all F1 plants are tall. If an F1 plant is crossed to a short-seeded plant, the expected ratio of tall: short in the progeny is?
A) 3 tall: 1 short
B) 1 tall: 1 short
C) 1 tall: 3 short
D) 1 tall: 0 short

B) 1 tall: 1 short

63

In tigers, a recessive mutation causes a white tiger. Two tigers with normal coloration are mated and produce a white offspring. What is the probability that they will have a white tiger cub when they mate next season?
A) 0.5
B) 0.0625
C) 0.66
D) 0.25

D) 0.25

64

When Mendel performed dihybrid crosses, he found a 9:3:3:1 ratio of phenotypes in the F2. This ratio shows that:
A) dominant genes are masked by recessive genes
B) the genes that control traits assort independently
C) only the double recessive genotype is true breeding
D) recessive genes are less common in the F2
E) both b and c

B) the genes that control traits assort independently

65

In humans, brown eyes (B) are dominant to blue eyes (b), and the ability to dance (D) is dominant to the lack of ability (d). A blue-eyed woman who cannot dance marries a brown-eyed, dancing man. Eleven of their 20 children have blue eyes and they all can dance. What are the genotypes of the children?
A) blue eyes bbD_ ; brown eyes B_D_
B) blue eyes bbDd; brown eyes BbDd
C) blue eyes bbDD; brown eyes BbDD
D) blue eyes bbDd; brown eyes BBDd

B) blue eyes bbDd; brown eyes BbDd

66

A couple from Regina are both heterozygous for the autosomal, recessive allele for albinism. What is the probability that three of their four children will be albino?
A) 91/256
B) 12/256
C) 36/256
D) 108/256

B) 12/256

67

Mendel crossed Y/Y;R/R (yellow, round) peas with y/y;r/r (green, wrinkled) peas. The F1 were all yellow and round. The F1 were selfed to generate the F2. What proportion of the green, round individuals from the F2 would be true-breeding?
A) 1/16
B) 3/16
C) 1/3
D) 1/9
E) 9/16

C) 1/3

68

What would be the phenotypic gender of an XXY individual in humans and Drosophila, assuming the normal number of autosomes.
A) Humans: female, Drosophila: female
B) H: male, D: male
C) H: male, D: female
D) H: female, D: male
E) H: male, D: intersex

C) H: male, D: female

69

A colour blind man (X-linked recessive) marries a woman with normal vision whose father was colour blind. _____ of their sons will be ____?
A) 1/2 carries
B) 3/4 normal
C) 1/2 colour blind
D) all colour blind

C) 1/2 colour blind

70

In a Drosophila experiment, a cross was made between homozygous wildtype females and yellow-bodied males. All of the F1’s were wildtype and were mated to generate the F2’s. The following phenotypes were observed in the F2’s.
Sex Phenotype Number of flies
Male Wild 123
Male Yellow 116
Female Wild 240

Is the mutant gene for yellow body dominant or recessive? Is the yellow locus sex-linked or autosomal?
A) recessive, sex-linked
B) recessive, autosomal
C) dominant, sex-linked
D) dominant, autosomal

A) recessive, sex-linked

71

Which of the following statements about sex chromosomes is/are true?
A) all organisms with separate sexes have sex chromosomes
B) sex chromosomes probably evolved multiple times during the course of vertebrate evolution
C) sex chromosomes are derived from autosomes
D) independent assortment of chromosomes means that >2 sex chromosomes within a species does not occur
E) statements b and c

E) statements b and c

72

The dosage compensation mechanisms discussed in class refer to _______.
A) formation of Barr bodies
B) down-regulation of transcription in males
C) up-regulation of transcription in females
D) all of the above
E) a and b only

A) formation of Barr bodies

73

In snap-dragon flowers, the allele coding for red flowers (R) shows incomplete dominance to the allele coding for white flowers (r). If two Rr individuals are crossed, the expected ratio of phenotypes in the offspring are:
A) 1 red: 2 pink: 1 white
B) 3 red: 1 white
C) 1 red: 2 red and white patches: 1 white
D) 1 pink: 1 white

A) 1 red: 2 pink: 1 white

74

You are studying coat colour in cattle. A true-breeding line with red coats is crossed to a true breeding line with white coats. The F1 are all red, and the F2 exhibit the ratio 9 red: 6 roan: 1 white. Roan coats are light red. What is the most likely genetic basis of roan coats?
A) incomplete dominance
B) Codominance
C) dominant allele(s) at one but not both of two independent loci
D) recessive epistasis
E) duplicate recessive epistasis

C) dominant allele(s) at one but not both of two independent loci

75

In mice, dominant allele A results in pigmented hairs and allele a causes albino hairs (no pigment, white appearance). A dominant allele at an independently assorting locus,B, causes agouti pigment and allele b causes black pigment. What ratio of progeny would occur if an AaBb (agouti) mouse was mated to an albino (aabb) mouse?
A) 9 agouti: 3 black: 4 white
B) 9 agouti: 6 black: 1 white
C) 1 agouti: 1 black: 2 white
D) 1 agouti: 2 black: 1 white

C) 1 agouti: 1 black: 2 white

76

In Drosophila, a mutant strain has plum-coloured eyes. A cross between two plum-eyed flies gives a ratio of 2 plum eyes: 1 red eye (wild type). What are the expected ratios of a cross between a plum eyed fly and red-eyed fly?
A) 1 plum: 1 red
B) 2 plum: 1 red
C) 1 plum: 2 red
D) all plum
E) all red

A) 1 plum: 1 red

77

Wizards may be born to muggle (non-magic) families but the children of a witch and a wizard can almost always perform magic, suggesting that the magic allele (m) is recessive to the muggle allele (M). However, occasionally mm children cannot perform magic (squibs). Based on the formation given above, the mm genotype most likely has:
A) complete penetrance and variable expressivity
B) incomplete penetrance and constant expressivity
C) incomplete penetrance and variable expressivity
D) complete penetrance and constant expressivity

B) incomplete penetrance and constant expressivity

78

Variation at a single locus has been shown to affect susceptibility to allergies in some human populations. Which conditions are most likely to result in the development of allergies in individuals with the susceptible genotype?
A) a large urban family
B) a small urban family
C) a small rural family
D) a large rural family

B) a small urban family

79

In Drosophila, a gene influencing wing shape is 10 map units from a gene for eye colour. A fly that is heterozygous at these genes for mutant alleles causing vestigial wings and apricot eyes (++ / vg ap) is test crossed. How many of the 1000 offspring will have a parental genotype?
A) 900
B) 450
C) 100
D) 50

A) 900

80

Assume that a cross is made between AaBb and aabb plants and the offspring occur in the following numbers: 106 AaBb, 48 Aabb, 52 aaBb, 94 aabb. These results are consistent with the following circumstance.
A) sex-linked inheritance with 33% crossing over
B) linkage with 50% crossing over
C) linkage with approximately 33 map units between loci
D) independent assortment

C) linkage with approximately 33 map units between loci

81

Genes A, B, and C are on the same chromosome with B in the middle. A is 30 map units from B, and C is 35 units from B. What is the expected recombination rate between A and C?
A) 65%
B) 50%
C) 10.5%
D) You cannot tell from these data

B) 50%

82

The following phenotypes are observed following a 3-point test cross of a heterozygous corn plant. What is the order of the genes involved?
++c=21
a++=174
a+c=3
+++=50
+b+=2
ab+=24
abc=48
+bc=178

A) BCA
B)ABC
C) CAB

A) BCA

83

If a double cross over occurs between two linked genes and involves only two chromatids, the resulting offspring will be _____.
A) parental only
B) recombinant only
C) half parental, half recombinant
D) mostly parental with a few recombinants
E) mostly recombinant with a few parentals

A) parental only

84

In a three point test cross, interference is a measure of,
A) the accuracy of map distances between all three genes
B) whether the genes are linked
C) whether the crossing data are reliable
D) how much the chiasma of one cross reduces the probability of double crossovers

D) how much the chiasma of one cross reduces the probability of double crossovers

85

Which type of genetic rearrangement is usually lethal in homozygous form?
A) deletion
B) inversion
C) translocation
D) duplication

A) deletion

86

Which of the following statements about polyploidy is true?
A) polyploidy does not occur in animals
B) polyploidy is rare compared to other types of mutations
C) polyploid plants usually have bigger cells resulting in higher yield in crop plants

C) polyploid plants usually have bigger cells resulting in higher yield in crop plants

87

In a human population in Hardy-Weinberg equilibrium for albinism (autosomal recessive), the frequency of albino newborns is 1 in 10,000. What proportion of newborns are heterozygous for albinism?
A) 0.02
B) 0.01
C) 0.025
D) 0.04
E) 0.013

A) 0.02

88

Which of the following is NOT an assumption of the Hardy-Weinberg equilibrium model?
A) there is no mutation
B) each individual has an equal chance of mating
C) the genotype with the highest frequency is most fit
D) migration is not occurring

C) the genotype with the highest frequency is most fit

89

Individuals that are heterozygous for the sickle-cell allele have slight anemia but are resistant to malaria. In regions where malaria is common, this is a good example of,
A) directional selection
B) heterozygote advantage
C) frequency-dependent selection
D) positive assortative mating

B) heterozygote advantage

90

If leaf length is controlled by a polygenic series with six segregating alleles, what is the ratio of individuals with the middle leaf length to individuals with the smallest length?
A) 1:20
B) 1:10
C) 10:1
D) 20:1

D) 20:1

91

You are studying quantitative genetics of fruit size in tomatoes. You found Vp of 100, Va of 35, Vd of 15, Vi of 10, and Ve of 40. Is this trait more influenced by genotype or environment in your population?
A) genotype
B) environment
C) both have an equal influence

A) genotype

92

You are studying effects of global warming on butterflies by exposing them to high temperatures. In the first generation, mean adult body size for the entire population was 45mg. However, reproductive individuals had a mean body size of 35mg. Mean adult body size in the second generation was 40mg. What was the selection differential on body size?
A) -5 mg
B) 5 mg
C) 10 mg
D) -10 mg

D) -10 mg

93

Areas of DNA that are rich in guanine are more stable than areas rich in thymine because ______.
A) guanine is less chemically reactive than thymine
B) thymine is replaced by uracil in RNA
C) guanine is a larger molecule than thymine
D) guanine and cytosine are joined by three hydrogen bonds

D) guanine and cytosine are joined by three hydrogen bonds

94

The proportion of A plus G in a molecule of double-stranded DNA is ____ the proportion of C plus T
A) equal to
B) less than
C) greater than
D) 1 minus

A) equal to

95

Introns are _________.
A) found only in prokaryotic pre-mRNA
B) indicated by the CAAT box at the 5’ end
C) transcribed and then removed
D) both A and C
E) bot B and C

C) transcribed and then removed

96

The E site on the ribosome _______.
A) is the Entry site for a charged tRNA
B) is the site from which an uncharged tRNA is released
C) is toward the 3’ end of the mRNA
D) both A and C
E) both B and C

B) is the site from which an uncharged tRNA is released

97

A peptide bond forms between the _____ of the amino acid and the ________ of another.
A) amino group; phosphate group
B) R group; R group
C) amino group; R group
D) carbxyl group; sulfide group
E) carboxyl group; amino group

E) carboxyl group; amino group

98

The following is part of an mRNA sequence for a wildtype allele:
5’-AUG GAA GGU CAU-3’

Which of the following mutations is a silent transversion?
A) GAA mutates to AAA
B) GAA mutates to GAG
C) CGU mutates to GGA
D) CAU mutates to GAU

C) CGU mutates to GGA