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Bio 309F
Examination #1
February 21, 2006
Name________________________________________
Note: please place your name and answers on the scantron. We will only grade the scantron so
double check to be sure the answers on the scantron are as you want them. Through out the
exam, please cover your answers with the sheet of paper provided. Do not use electronic
gadgets, including telephone--so, please turn off your telephone prior to starting the exam.
I. Multiple Choice (2 points/question, 50 questions for 100 points).
1. A woman gives birth to monozygotic twins. One boy has a normal genotyope (46
chromosomes), but the other boy has trisomy 13 (47 chromosomes). What event(s) let to the
trisomic twin?
A. non-disjunction at the first meiotic division in the mother or father
B. non-disjunction at the second meiotic division in the mother or father
C. non-disjunction at the first meiotic division in the mother
D. non-disjunction as a mitotic event after zygote formation
E. A, B, and D are correct
2. What is the chromosomal alteration resulting in 5P- (cri du chat "cat cry" ) syndrome?
A. duplication
B. deletion
C. inversion
D. translocation
E. A, B, C, and D could give rise to 5P- syndrome
3. Which of the following is/are false?
A. At least one copy of an X chromosome is essential for survival
B. Extra copies of either sex chromosome interferes with normal development
C. Most XO embryos/fetuses are spontaneously aborted
D. YY zygotes undergo embryonic/fetal development but die at birth
E. There are no false answers, all the answers are true
4. The following are true about the offsprings of a female carrier of an X-linked
recessive disorder and a normal male:
A. half of their children will be symptomatic (express the phenotype)
B. half of their daughters will be symptomatic
C. half of their sons will be asymptomatic (not express the phenotype)
D. half of their daughters will be carriers
E. C and D are correct
5. An allele is ___.
A. one of the bases in DNA
B. an alternate form of a gene
C. another term for epistasis
D. present only in males and is responsible for sex determination
E. found in mitochondria but not in nuclei
6. In dihybrid crosses, the ratio 9:3:3:1 indicates ___.
A. Codominance
B. Independent assortment
C. Intermediate dominance
D. Three alleles for each trait
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7. In a cross of a round hybrid pea plant with a true breeding round pea plant (Ww x WW),
which of the following would be expected in the offspring?
A. Half heterozygous, half homozygous dominant
B. Half round, half wrinkled
C. All heterozygous
D. All round
E. A and D are correct
8. The fundamental Mendelian process which involves the separation of contrasting genetic
elements at the same locus would be called ___.
A. separation of alleles
B. independent assortment
C. continuous variation
D. discontinuous variation
E. dominance or recessiveness
9. What ratios typically result from crosses dealing with a single genetic locus?
A. 9:3:3:1, 1:2:1
B. 1:1:1:1, 1:4:6:4:1
C. 3:1, 1:1, 1:2:1
D. 9:7, 12:3:1
E. 15:1, 1:2
10. There are three different genotypes resulting from a monohybrid cross. How many different
genotypes would there be resulting from a dihybrid cross?
A. 4
D. 9
B. 6
E. 16
C. 8
11. Starting with a cross between AA and aa, the proportion of heterozygotes in the F2
progeny will be ___.
A. 1/8
B. 1/4
C. 1/3
D. 1/2
F. All heterozygotes
11. Albinism, lack of pigmentation in humans, results from an autosomal recessive gene
designated a. Two parents with normal pigmentation have an albino child. What is the
probability that their next child will be albino? What is the probability that the next child will be
an albino girl?
A. 1/2; 1/4
B. 1/4; 1/2
C. 1/4; 1/8
D. 1/8; 1/4
E. 1/4; 3/4
12. Starting with a P (parental) generation with the following genotypes (AABB x aabb). Based
on classical Mendelian inheritance, what is the expected phenotypic ratio observed among the F2
progeny?
A. 9:3:3:1
D. 1:1
B. 1:2:1
E. 1:1:1:1
C. 3:1
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13. A species of mice can have gray or black fur and long or short tails. A cross between blackfurred, long-tailed mice and gray-furred, short-tailed mice produce all black-furred, long-tailed
offspring. Using the gene symbols G for black, g for gray, S for long and s for short, what would
be the genotype of a gray-furred, short-tailed mouse?
A. GGSS
B. ggSS
C. ggss
D. GgSs
E. Ggss
14. In a F1 dihybrid cross (WwGg X WwGg) where W = round, w = wrinkled, G = yellow and g
= green, what is the probability of obtaining a plant that is wrinkled, green and true-breeding?
A. 1/16
B. 1/2
C. 9/16
D. 3/16
E. 1/4
15. With co-dominance, a likely ratio resulting from a monohybrid cross would be ___.
A. 3:3
B. 1:2:2:4
C. 1:2:1
D. 9:3:3:1
E. 3:1
16. During anaphase of mitosis
A. DNA recombines
B. Sister chromatids move to opposite poles
C. The nuclear membrane disappears
D. RNA replicates
E. DNA content essentially doubles
17. During prophase of mitosis ___.
A. DNA recombines
B. Sister chromatids move to opposite poles
C. The nuclear membrane disappears
D. RNA replicates
E. DNA content essentially doubles
18. Chromosomes that contain the same sets of genes and pair up in meiosis I are called ___?
A. homologous
B. heterologous
C. complementary
D. non-disjunctive
E. parallel
19. Which of the following processes occurs in meiosis but not mitosis?
A. Cell division
B. Separation of homologous centromeres to opposite poles
C. Chromatic formation.
D. Chromosome condensation (shortening)
E. Pairing of homologs.
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20. In which part of the cell cycle of a eukaryotic cell is the DNA replicated?
A. during interphase
B. immediately before telophase
C. immediately after telophase
D. as a part of cytokinesis
E. during metaphase
21. When an organism gains or loses one of more chromosomes but not a complete haploid
set, the conditions is known as
A. polyploidy
B. euploidy
C. aneuploidy
D. triploidy
E. trisomy
22. It was once thought that the ____ karyotype was related to criminal disposition because it
led to aggressive behavior due to excessive "maleness".
A. XO
B. XY
C. XXY
D. XYY
E. YY
23. Euploidy is
A. a chromosome number that is not an exact multiple of the haploid number
B. an example of aneuploidy
C. a chromosome number that is an exact multiple of the haploid number
D. the addition of an extra copy of a particular chromosome
E. the absence of a particular copy of a chromosome
24. Consider a species with a diploid (2n) number of 16 chromosomes. How many
chromosomes would be found in a trisomic somatic cell?
A. 8
B. 9
C. 16
D. 17
E. 24
25. Consider a species with a diploid (2n) number of 28 chromosomes. How many
chromosomes would be found in a haploid body cell?
A. 7
B. 14
C. 15
D. 28
E. 29
26. Turner syndrome in humans is caused by which chromosomal conditions?
A. 47, XXY
B. 47, 21+
C. 45, X
D. 47, XYY
E. triploidy
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27. 47, XXY is a condition known as
A. Trisomy-X syndrome
B. Klinefelter syndrome
C. Turner syndrome
D. Double-Y syndrome
E. Fragile-X syndrome
28. Consider a species with a diploid (2n) number of 10 chromosomes. How many
chromosomes would be found in a monosomic somatic cell?
A. 9
D. 20
B. 10
E. 21
C. 11
29. In humans, males transmit the Y chromosome to
A. their daughters but not their sons
B. both their sons and daughters
C. their sons but not to their daughters
D. neither son nor daughters
30. The outward appearance of an organism is called its
A. genotype
B. phenotype
C. allele
D. hereditary potential
E. lack of dominance
31. Which statement(s) is/are false in regards to X-linked (sex-linked) recessive traits?
A. transmitted from non-affected mother to all sons
B. hemizygous males and homozygous females are affected
C. phenotypic expression is much more common in males than females
D. transmitted from affected father to sons and daughters
E. A and D are false statements
32. Example of a sex-linked recessive trait in humans is/are:
A. Huntington’s Disease
B. hypophosphatemia
C. hemophilia
D. Marfan syndrome
E. B and D are correct
33. Example of an autosomal dominant trait in humans is/are:
A. Cystic Fibrosis
B. hypophosphatemia
C. hemophilia
D. Marfan syndrome
E. B and D are correct
34. A normal man and a normal woman have a son who is a hemophiliac. What is the son’s
genotype?
A. XY
B. XhX
C. XhY
D. XhXh
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35. A woman who is heterozygous for colorblindness marries a normal male. They are
expecting their first child. What is the probability that their child will be colorblind?
A. 25%
D. 100%
B. 50%
E. 0%
C. 75%
36. The child in question #24 at birth is a normal female. What is the probability that this
female is a carrier of colorblindness just like her mother?
A. 0
D. 1/3
B. ½
E. 2/3
C. 1/4
37. Coat color in rabbits is controlled by a single pair of genes for which there are four possible
alleles. This is an example of
A. a multiple-gene trait
B. codominance
C. incomplete dominance
D. multiple alleles
E. incomplete penentrance
38. Human traits such as skin color and height are
A. the product of a single pair of alleles
B. the product of genes located on the sex chromosomes
C. the product of more than one pair of alleles
D. the product of multiple genes and by environmental factors
E. the product only of environmental factors
39. Obesity in humans is
A. the product of a single pair of alleles
B. the product of genes located on the sex chromosomes
C. the product of more than one pair of alleles
D. the product of multiple genes and by environmental factors
E. the product only of environmental factors
40. Extensive pedigree analysis usually permits all of the following, except:
A. an orderly presentation of family information
B. the determination of whether a trait is genetic
C. the determination of whether a trait is dominant or recessive
D. characterization of which gene is involved in a heritable disorder
E. the determination whether a trait is sex-linked or autosomal
41. Which of the following is/are example(s) of co-dominant inheritance?
A. familial hypercholesterolemia
B. ABO blood types
C. intelligence
D. height
E. skin pigmentation
42. Maternal inheritance refers to:
A. traits that daughters receive from their mothers and pass on to their daughters only
B. traits that daughters receive from their mothers and pass on to their daughters and sons
C. traits that sons receive from their mothers and pass on to their children
D. traits that sons receive from their mothers but do not pass on to their children
E. B and D
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43. Genes that are linked to the same chromosome
A. will assort independently
B. will not assort independently
C. will produce a greater number of individuals with parental(non-recombinant)
D. will produce a fewer number of individuals with recombinant genotypes
E. B, C, and D are correct
genotypes
44. An individual has been exposed to high energy radiation that caused numerous chromosome
breaks. Karyotypic analyses revealed a "cross configuration". This indicates chromosome
breaks and the cross configuration is most likely due to:
A. exchange of chromosomal segment between homologous chromosomes
B. exchange of chromosomal segment between non-homologous chromosomes
C. deletion of chromosomal segment
D. inversion of chromosomal segment
E duplication of chromosomal segment
45. Karyotypic analyses showing a "large loop" most likely indicate:
A. translocation
B. inversion
C. deletion
D. duplication
E. B, C, and D are correct
46. Somatic cells from a spontaneously aborted fetus reveals 69 chromosomes. This is
indicative of:
A. diploidy
D. aneuploidy
B. triploidy
E. trisomy
C. tetraploidy
47. Karyotypic analyses of a developing fetus can be accomplished using:
A. chorionic villus sampling
B. amniocentesis
C. fetal cell sorting
D. A and B are correct
E. A, B, and C are correct
48. Major risk factor(s) in having a Down Syndrome child is/are:
A. delaying having children until female is older
B. chromosome 21 reciprocal translocation
C. chromosome 21 mosaic
D. A and B are correct
E. A, B, and C are correct
49. A primary spermatocyte in humans will give rise to ______ sperm
A. one
D. four
B. two
E. five
C. three
50. A primary oocyte in humans will give rise to _____egg
A. one
D. four
B. two
E. five
C. three