MULUNGUSHI UNIVERSITY
SCHOOL OF SCIENCE, ENGINEERING AND TECHNOLOGY (SSET)
DEPARTMENT OF MATHEMATICS AND SCIENCE
FINAL EXAMINATION
BIO 112-MOLECULAR BIOLOGY AND GENETICS
Duration: 3hrs
Date: FRIDAY- 05/06/2020
INSTRUCTIONS
 THIS PAPER HAS 100 MULTIPLE CHOICE QUESTONSANSWER ALL
 USE MOODLE TO ANSWER ALL QUESTIONS (NO
SCANNED COPPIES SHOULD BE UPLOADED; THEY’LL
NOT BE MARKED)
 THE EXAM WILL BE AVAILABLE FOR 24HRS, BUT
ONCE YOU START WRITING; YOU HAVE ONLY 3
HOURS TO COMPLETE.
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1. A boy is born with an extra finger on one hand. Extra digits are known to be common in
members of the father's extended family, but not the mother's. The boy's two sisters have
normal fingers. What is the most likely explanation?
A. X-linked inheritance, since only males are affected
B. Y-linked inheritance: Males inherit from their fathers
C. The extra finger trait is autosomal dominant
D. A spontaneous mutation occurred
2. In the father's family, both men and women show extra digits, sometimes an extra finger
on both hands, sometimes just one hand, sometimes extra fingers and toes. What do we
call this phenomenon?
A. Multiple gene loci combining to produce the trait
B. Variable expressivity of the trait, though all affected individuals carry the same allele
C. Gene product interaction
D. Different mutations in the same family
3. Suppose the boy's aunt and her husband have no extra fingers--yet their child has an extra
finger! How do we explain this, if the trait is dominant?
A. The professor made a mistake in the test
B. The allele changed from recessive to dominant
C. The aunt's husband has a recessive allele for a different gene locus that results in the
same phenotype
D. The gene for extra finger shows partial penetrance
4. In a family, mildly retarded girls have children with more profound retardation. The Xchromosome shows a multiple triplet repeat. What is the explanation?
A. The condition is double-recessive; the father also carries the allele
B. The condition is caused by expansion of the triplet repeat region in each generation, a
non-random form of mutation. The expanded non-coding DNA region turns off
expression of a nearby essential gene
C. X-linked inheritance
D. Variable expressivity
5. A pair of yellow mice produce a litter of five yellow mice and one white. One mouse of
indeterminate color is stillborn. Suggest an explanation.
A. Yellow trait is codominant; two "yellow" alleles cause lethality
B. This "five to one to one" ratio must be explained by multiple gene loci
C. The mice have different fathers
D. Multiple alleles cause three different phenotypes
6. When the yellow mice are examined physiologically, the yellow color is determined to
result from jaundice; the trait causes a liver defect. Multiple effects of one gene
illustrates:
A. Multiple alleles
B. Multiple gene loci
C. Pleiotropy
D. Partial penetrance
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7. A father with type A blood and a mother with type B blood have three children with
blood of type AB and type O. Explain.
A. Three different gene loci cause A, B, and O type
B. There are multiple alleles for A, B, and O; The parents are genotype AO and BO
C. O blood type shows partial penetrance
D. O blood type shows partial expressivity
8. If two parents are homozygous for a genetically inherited recessive trait, what is the
probability that they will have a child who does not have this trait in his or her
phenotype?
A. 0%
B. 25%
C. 50%
D. 100%
9. If the genes for a trait are inherited by both men and women but only show up in the
phenotype of women, they are referred to as _____________ genes.
A. sex controlled
B. codominant
C. sex-limited
D. Incomplete dominant
10. If there is a family history of genetic disorders, knowing the gender of an unborn child
can be important because:
A. male children are more likely to have autosomal defects show up in their phenotypes.
B. female children are more likely to have autosomal defects show up in their
phenotypes.
C. male children are more likely to have X-linked traits show up in their phenotype.
D. A and C
11. A chromosomal abnormality that causes a woman to be unusually short in stature
(average 4'7"), to have a webbed neck, and to generally lack feminine secondary sexual
characteristics is:
A. Triple-X syndrome
B. Turner syndrome
C. XYY syndrome
D. Down syndrome
12. Two true breeding parents are crossed similar to Mendel's P generation. A tall plant is
crossed with a short plant. What is the expected outcome for the F1 generation?
A. All short
B. All tall
C. all medium height
D. half tall, half short
13. If the cross from #1 is continued, what would be the expected outcome in the F2
generation?
A. all short
B. all tall
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C. 3 tall, 1 short
D. half tall, half short
14. In each case where Mendel crossed true breeding plants as parents, the offspring
displayed only one of the two traits seen in the parents. This observation supports which
principle of genetics?
A. Segregation
B. independent assortment
C. dominance and recessiveness
D. allele frequency
15. Which of the following outcomes would you expect from the following cross: tall, round
(TTRR) x short, wrinkled (ttrr)
A. all offspring tall and round
B. all offspring short and wrinkled
C. half tall, round; half short wrinkled
D. 9:3:3:1
16. A plant that has purple flowers is crossed with one that has white flowers. The offspring
were half white and half purple. What were the genotypes of the parents?
A. Pp x pp
B. Pp x Pp
C. PP x pp
D. PP x WW
17. A cell with 10 chromosomes undergoes mitosis. How many daughter cells are created?
___ Each daughter cell has ___ chromosomes.
A. 2, 10
B. 10, 2
C. 1, 10
D. 2, 20
18. What structure is responsible for moving the chromosomes during mitosis?
A. Nucleolus
B. Centriole
C. Spindle
D. Cytoplasm
19. Cells will generally divide when?
A. they are 10 hours old
B. they become infected
C. they become too large
D. they have no food
20. The process of mitosis ensures that:
A. each new cell is genetically different from its parent
B. each new cell receives the proper number of chromosomes
C. cells will divide at the appropriate time
D. DNA is replicated without errors
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21. Compared to the X chromosome, the Y chromosome is:
A. much larger
B. much smaller
C. more twisted inherited
D. more often
22. Meiosis is a type of cell division that produces:
A. zygotes
B. chromosomes
C. DNA
D. Gametes
23. Which of the following distinguishes prophase 1 of meiosis from prophase of mitosis?
A. homologous chromosomes pair up
B. spindle forms
C. nuclear membrane breaks down
D. chromosomes become visible
24. Which of the following is NOT part of the chromosome?
A. Kinetochore
B. chromatid
C. centromere
D. spindle
25. Polygenic traits are ones that are:
A. controlled by more than just a single pair of alleles
B. controlled by more than just a single pair of alleles
C. found in either men or women but not both
D. B and C
26. Failure of homologous chromosomes to separate during meiosis Results in gametes with
either one extra or one missing chromosome. This is known as
A. Translocation
B. Nondisjunction
C. Replication
D. Transcription
27. Why are insertion and deletion mutations so harmful?
A. They change all of the codons from the mutation on down the line, which changes the
amino acid sequence
B. They insert things that an organism doesn't need
C. They often delete things that organisms need
D. Insertion and deletions are not any more harmful than substitution mutations
28. Mitochondrial genes are
A. located within the nucleus
B. maternally inherited
C. paternally inherited
D. not inherited at all
29. Increasing high skin cancer and high mutation rate are
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A. O3 depletion
B. Acid rain
C. CO pollution
D. CO2 Pollution
30. The sickle cell trait
A. Is common in people whose ancestors came from areas where malaria was a
significant health problem because of a serious bottleneck effect
B. Is an example of a null mutation
C. Results in resistance to malaria among people homozygous for the trait
D. None of the above
31. Which of the following is an example of polygenic inheritance?
A. Pink flowers in snapdragons
B. The ABO blood groups in humans
C. White and purple flower color in peas
D. Skin pigmentation in humans
32. If two parents are heterozygous for a genetically inherited dominant trait, what is the
probability that they will have a child together who has this trait in his or her phenotype?
A. 25%
B. 50%
C. 75%
D. 100%
33. In a dihbrid cross, there is usually four possible phenotypes. How many degrees of
freedom does this translate into using the chi-square test?
A. 0
B. 1
C. 2
D. 3
34. You produced 639 plants with the following phenotypes
round yellow gray 269
round yellow white 98
round green gray 86
wrinkled yellow gray 88
round green white 27
wrinkled yellow white 34
wrinkled green gray 30
wrinkled green white 7
The (observed-expected) was as follows round yellow white 65.61
round green gray 15.21 wrinkled yellow gray 3.61 round green white 8.41 wrinkled
yellow white 16.81 wrinkled green gray 0.01 wrinkled green white 9.00
What is the chi-square value?
A. 3.987
B. 0.05
C. 2.684
D. 7.764
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35. From the above question, how many degrees of freedom are there?
A. 3
B. 5
C. 7
D. 9
36. From the above question, the chi-square probability lies between ____.
A. .99 and .975
B. .975 and .95
C. .95 and .9
D. .9 and .1
37. A chi-square value of 10 _________.
A. would reject a hypothesis
B. would support a hypothesis
C. could do neither without knowing the degrees of freedom
D. would mean that the differences between expected and observed values were due to
chance alone
38. The chi-square test is used _____________________.
A. to prove a hypothesis
B. to determine the probability that the difference between observed and expected
results are due to random chance
C. to determine the standard deviation of your results
D. a and b, but not c
39. Which of the following statements is true regarding karyotype analysis?
A. It is rarely done on the cells of unborn children because it cannot detect most genetic
disorders
B. It is now an important medical tool used in predicting the likelihood that an unborn
child will be normal.
C. It is not done any more because human pregnancy has only a small risk of birth
defects
D. It does not give any information if an individual will have an abnormality or not.
40. If there is a family history of genetic disorders, knowing the gender of an unborn child
can be important because:
A. male children are more likely to have autosomal defects show up in their phenotypes
B. female children are more likely to have autosomal defects show up in their
phenotypes
C. male children are more likely to have X-linked traits show up in their phenotype
D. A and C
41. The likelihood of a child being born with a major genetic defect, such as mental
retardation, can often be detected by sampling:
A. the mother's uterus cells
B. cells from the embryo or fetus
C. the father's blood cells
D. somatic cells
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42. Which of the following statements is true of sex chromosome abnormalities in humans?
A. They usually have mild effects and rarely are fatal.
B. Most are not gender specific
C. They cannot be diagnosed before birth
D. They are not passed to the next generation
43. Male sex chromosome abnormalities can be due to abnormal numbers of
______________ chromosome.
A. the X
B. the Y
C. either the X or the Y
D. none of the above
44. A chromosomal abnormality that causes a man to have asexual to feminine body contours
with large breasts; small penis, testes, and prostate gland; relatively little body hair; and
sterility is:
A. Klinefelter syndrome
B. XYY syndrome
C. Richard Speck Syndrome
D. Down syndrome
45. Polygenic traits are ones that are:
A. controlled by more than just a single pair of alleles
B. Responsible for a number of traits in the phenotype
C. found in either men or women but not both
D. caused by defects in mitochondrial DNA
46. The fact that monozygotic twins do not have identical phenotypes despite the fact that
they may look alike is an indication that:
A. their genotypes are not identical
B. phenotypes are a result of both the genotype and environmental influences
C. their phenotypes are not in any way due to their genotypes
D. high mutation rates in twins
47. An allele is:
A. another word for a gene
B. a homozygous genotype
C. a heterozygous genotype
D. one of several possible forms of a gene
48. When the genotype consists of a dominant and a recessive allele, the phenotype will be
like _________________ allele.
A. the dominant
B. the recessive
C. neither
D. heterozygous
49. The idea that for any particular trait, the pair of alleles of each parent separate and only
one allele from each parent passes to an offspring is Mendel's principle of:
A. independent assortment
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B. hybridization
C. segregation
D. codominance
50. Which of the following steps would NOT lead to variation of genetic mate rial?
A. Crossing over of non-sister chromatids
B. The alignment of the chromosomes during metaphase I
C. The combination of sperm and egg genes
D. Mutations
51. Which of the following statements is true about gene regulation in bacteria?
A. Activator proteins bind near promoters and increase efficiency of translation
B. Small-molecule “sensors” usually bind DNA and change its 3D structure
allosterically
C. Genes with related functions are often grouped together and have a single start codon
D. Repressor proteins block transcription by binding to operator sequences
52. Prokaryotic cells can have more than one functional start codon per mRNA because:
A. Both transcription and translation happen in the same cellular compartment
B. The activity of the lac repressor is regulated based on the physiological conditions
C. Prokaryotic promoters consist of two separated sequences: the -10 box and the -35
box
D. Prokaryotic ribosomes bind to Shine-Dalgarno sequences
53. Which of the following is true about DNA polymerase?
A. It can synthesize DNA in the 5’ to 3’ direction
B. It can synthesize DNA in the 3’ to 5’ direction
C. It can synthesize mRNA in the 3’ to 5’ direction
D. It can synthesize mRNA in the 5’ to 3’ direction
54. The reaction in DNA replication catalyzed by DNA ligase is
A. Addition of new nucleotides to the leading strand
B. Addition of new nucleotide to the lagging strand
C. Formation of a phosphodiester bond between the 3’-OH of one Okazaki fragment and
the 5’-phosphate of the next on the lagging strand
D. Base pairing of the template and the newly formed DNA strand
55. Which of the following reactions is required for proofreading during DNA replication by
DNA polymerase III?
A. 5’ to 3’ exonuclease activity
B. 3’ to 5’ exonuclease activity
C. 3’ to 5’ endonuclease activity
D. 5’ to 3’ endonuclease activity
56. Protein synthesis in bacteria takes place on which of the following organelles?
A. Endoplasmic Reticulum
B. Golgi body
C. Ribosomes
D. Mitochondria
ANSWER: C
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57. Which of the following RNA constitutes 90 percent of the total cellular RNA?
A. rRNA
B. tRNA
C. mRNA
D. hnRNA
58. The synthesis of polynucleotide chain of mRNA is catalyzed by the enzyme
_____________
A. Primase
B. RNA polymerase
C. DNA polymerase
D. DNA helicase
59. Which of the following are non-sense codons?
A. AUG
B. GUG
C. UAA
D. UCU
60. Which is a characteristic of the normal genetic code?
A. One codon can code for only one amino acid
B. One amino acid can have only one codon
C. One tRNA molecule can bind to only one codon.
D. One aminoacyl-tRNA synthetase can react with only one Trna
61. Which is a property of the introns in most eukaryotic pre-mRNA?
A. Introns are extra coding sequences that can be removed by an RNA- protein complex
B. Introns are non-coding sequences that separate exons in monocistronic pre-mRNA
C. Introns are palindromic sequences that self-splice to form lariat structures
D. Introns can remain in mature mRNA due to alternate splicing pathways
62. A mutated E. coli cell contains a slightly altered RNA polymerase which does not
function normally but still allows the cell to survive. Which problem is unlikely to be the
result of this altered RNA polymerase?
A. Some genes may be transcribed more frequently than normal
B. Some mRNA molecules may be longer than normal
C. The non-template strand may be transcribed in some genes
D. There may be an increased number of mRNA molecules with incorrect bases
63. Which characteristic is shared by both RNA polymerase and DNA pol III in E. coli?
A. Both function as holoenzymes that have polymerase and helicase activities
B. Both use promoters to locate and bind to the starting point of genes
C. Both produce nucleic acid molecules that become permanent cellular components
D. Both use templates to synthesize an anti-parallel, complementary nucleic acid chain
64. Which is a characteristic of mRNA in E. coli?
A. mRNA will be polycistronic and double-stranded
B. mRNA will be monocistronic and single-stranded
C. mRNA will contain one or more non-coding spacer sequences
D. mRNA will contain one or more coding leader sequences
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65. If DNA polymerase I were mutated so that all its enzymatic activities were inactive,
which part of replication would be most affected?
A. synthesis of Okazaki pieces
B. joining of Okazaki pieces
C. proof-reading of DNA
D. adjusting of supercoiling
66. Which protein can catalyze the formation of phosphodiester bonds?
A. DNA ligase
B. Helicase
C. Dna B protein
D. Gyrase
67. During initiation of replication
A. DNA polymerases denature A-T rich sequences at the origin
B. replication begins when Dna A protein binds the origin and synthesizes primers
C. DnaB protein cleaves the double-helix to produce template strands
D. two replication forks need to be created to establish bidirectional replication
68. Which is a characteristic of an E. coli replication fork and a eukaryotic replication fork?
A. Both forks contain a leading strand and a lagging strand
B. Polymerization occurs more rapidly in eukaryotes
C. Okazaki pieces are smaller in prokaryotes
D. Both forks can synthesize DNA only during S phase
69. Which is a property of Okazaki pieces in an E. coli replication fork?
A. Okazaki pieces are joined together by DNA polymerase I to form a long chain.
B. Okazaki pieces are polymerized in the 3′→ 5′ direction by DNA polymerase III.
C. An Okazaki piece for the leading strand is polymerized to a length of 1000-2000
nucleotides.
D. An Okazaki piece for the lagging strand has a base sequence complementary to its
template.
70. Which of the following describes the relationship between chromosomes and DNA
molecules?
A. Each chromosome is made of a single DNA molecule
B. Each chromosome is made of more than one DNA molecule
C. Each DNA molecule is made of more than one chromosome
D. There is no relationship between chromosomes and DNA molecules
71. In humans, where does DNA replication take place?
A. Cytoplasm
B. Ribosomes
C. Nucleus
D. Cell membrane
72. During translation, the type of amino acid that is added to the growing polypeptide
depends on the
A. codon on the mRNA and the anticodon on the rRNA
B. anticodon on the mRNA and the anticodon on the tRNA
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C. anticodon on the rRNA and the codon on the mRNA
D. codon on the mRNA and the anticodon on the Trna
73. In case of transcription which is the rate limiting step?
A. Binding of RNA polymerase
B. Unwinding of DNA duplex
C. Promoter escape
D. Formation of the open complex
74. Operons are ___________
A. of approximately uniform size
B. found in some eukaryotes
C. not able to bind to proteins
D. smaller in lower eukaryotes and longer in higher eukaryotes
75. Choose the correct pair among the following.
A. The DNA sequence to which stigma factor binds – enhancer
B. The DNA sequence to which RNA polymerase binds – operator
C. The DNA sequence that codes for a protein – structural gene
D. The DNA sequence to which repressors binds – promoter
76. Which of the following is not present in the β-galactosidase structural gene and thus is
not transcribed by the same promoter?
A. Lac A
B. Lac I
C. Lac Z
D. Lac Y
77. Glucose, as the carbon source, is the first choice by bacteria even if other sugars are
available. The mechanism behind this selectivity is ___________
A. Operon repression
B. Glucose utilization
C. Enzyme repression
D. Catabolite repression
78. The lac operon is regulated by cAMP by ___________
A. Binding to lac repressor
B. Binding to operator
C. Binding to promoter
D. Binding to catabolite activator protein
79. Which of the following is true about tryptophan operon?
A. Tetramer of identical subunits
B. The RNA product is very stable
C. The Trp repressor binds to the tryptophan
D. The Trp repressor is the product of the Trp operon
80. Name the enzyme which degrades DNA molecule by breaking its phosphodiester bonds?
A. DNA polymerase
B. Nucleases
C. Ligase
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D. Reverse transcriptase
81. Post-translational modifications of proteins can affect which of the following?
A. protein function
B. transcriptional regulation
C. chromatin modification
D. all of the above
82. the events in post transcriptional modification are listed asi) Polyadenylation ii) capping iii) splicing. What would be the correct sequence?
A. i->ii->iii
B. iii->ii->i
C. i->iii->ii
D. ii->i->iii D
83. Which nucleotide is present in the 5’ cap?
A. ADP
B. GDP
C. CDP
D. UDP
84. Which of the following are involved in post-transcriptional control?
A. control of RNA splicing
B. control of RNA shuttling
C. control of RNA stability
D. all of the above
85. Binding of an RNA binding protein will ________ the stability of the RNA molecule.
A. Increase
B. Decrease
C. neither increase nor decrease
D. either increase or decrease
86. Alternative splicing has been estimated to occur in more than 95% of multi-exon genes.
Which of the following is not an evolutionary advantage of alternative splicing?
A. Alternative splicing increases diversity without increasing genome size
B. Different gene isoforms can be expressed in different tissues
C. Alternative splicing creates shorter mRNA transcripts
D. Different gene isoforms can be expressed during different stages of development
87. Which of the following is not a type of post translational modification?
A. Proteolysis
B. Protein folding
C. Glycosylation
D. Lipid addition
88. If the insertions of three nucleotides occur in a consecutive manner it causes which of the
following type of mutation?
A. Missense mutation
B. Stop mutation
C. Frame shift mutation
D. Reverse mutation
89. What molecule is used to signal low glucose levels to the Lac operon regulatory system?
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A. Cyclic AMP
B. Calcium
C. Lactose
D. Pyruvate
90. Found in some enteric bacteria and E.coli, Lac operon is an operon necessary for transfer
and metabolism of lactose. The lac operon of E.coli comprises genes involved in the
metabolism of lactose which gets expressed only in the presence of lactose and absence
of glucose. Lac operon is an example of
A. only positive regulation
B. only negative regulation
C. both positive and negative regulation
D. sometimes positive sometimes negative
91. In the presence of lactose, how long does it take for the lac operon to be expressed?
A. when lactose equals glucose concentration
B. when glucose is more than lactose concentration
C. as long as lactose is more than glucose concentration
D. as long as lactose is more than galactose concentration
92. Which of these acts as an inducer of lac operon is
A. Allolactose
B. Lactose
C. Galactose
D. Glucose
93. Regulation of the lac operon can be envisioned as regulation of enzyme synthesis by its
A. lactose
B. substrate
C. carbohydrates
D. all of the above
94. Lac Operon will be turned on when
A. Lactose is less than glucose
B. Lactose is less in the medium
C. Lactose in more than glucose
D. Glucose is enough in the medium
95. This will be prevented if the activator fastens to the repressor
A. Transcription
B. Binding of the RNA polymerase to promoter
C. Binding of the repressor to the operator
D. Binding of the repressor to the promoter
96. In Lac-operon, the gene product of LacA gene is
A. Beta-galactoside permease
B. Beta-galactoside transacetylase
C. Beta-galactosidase
D. Beta-galactoside isomerase
97. This condition in lac operon facilitates the condition of lac genes being transcribed at
high levels
A. low glucose, high lactose
B. low glucose, low lactose
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C. high glucose, high lactose
D. high glucose, low lactose
98. The correct option regarding the lac operon in E.coli from the following is
A. Lac operon is switched on in the absence of lactose
B. Lac repressor binds to the lac promoter
C. β-galactosidase is the only enzyme produced in large quantities when lac operon is
turned on
D. lac operon messenger RNA is a polycistronic Mrna
99. Methylation of _______________ decreases gene transcription, and is the basis of
imprinting.
A. adenine
B. cytosine
C. guanine
D. uracil
100.
A polyA tail is added to:
A. All eukaryotic RNAs
B. Prokarotic and Eukaryotic mRNAs
C. Eukaryotic mRNAs
D. Prokarotic and eukaryotic rRNAs.
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