1. In Humans, many types of cancers have been linked to? A. Duplications B. Inve
ID: 11670 • Letter: 1
Question
1. In Humans, many types of cancers have been linked to?A. Duplications
B. Inversions
C. translocations
D. deletions
E all of these
2. 5- bromoouracil is mutagenic because it is a(n)
a. base-modifying agent
b. base analog
c. intercalating agent
d. alkylating agent.
3.Ultraviolet radiation creates __________ in DNA
A. 5-methyl cytosine residues
B. breakages
C point mutations
D. mutational hot spots
E thymine dimers
4. The telomeres of chromosomes is composed of
A. heterochromatin
b. nucleosome
c. histone
d. achromatic
5. In eukaryotes, a replicon is
a. the distance between the origin of replication and the termination of replication
b. a single chromosome
c. the entire genome
d. one DNA strand of a single chromosome
6. In a nonreciprocal interchomosomal translocation, a segment of a chromosome is
a. exchanged with an identical segment on a different chromosome
b. exchanged with an identical segment on a sister chromatid
c. transferred to a different chromosome without a reciprocal exchange of genetic material
d. transferred to a new location on the same chromosome without a reciprocal exchange of genetic material
7. Somatic mutations are always.
a. spontaneous
b. carcinogenic
c. heritable
d. lethal
e. none of these
8. A woman with an XO genotype is
a. aneuploid
b. euploid
c. diploid
d. poluploid
9. Spontaneous mutations may occur as a result of
a. all of these
b. errors in DNA replication
c. transposition
d. none of these
e. normal cell biochemistry
10. In the semi conservative model of DNA replication, progeny double helices consist of
a. one parental DNA strand and one new strand
b. one parental DNA strand and one new RNA strand
c. two new RNA strands
d. two parental DNA strands
e. two new DNA strands
11. A mutation in a gene may alter a cell’s
a. phenotype
b. genotype and phenotype
c. genotype
12. During replication, the direction of synthesis of new DNA from the leading strand is
a. both 5’ to 3’ and 3’ to 5’
b. none of these
c. 3’ to 5’
d. from left to right only
e. 5’ to 3’ only
13. A mutation that results in a switch from a purine-pyramiding base pair to a pyramiding-purine base pair is a _________ mutation.
a. neutral
b. transition
c. missense
d. transversion
e. nonsense
14. A trisomic human cell would contain how many chromosomes?
a. 45
b. 46,
c. 47.
d. 48
15. In a strand of DNA, a _____________ bond connects the phosphate group of one nucleotide to the sugar of the adjacent nucleotide
a. hydrogen
b. ester
c. phosphodiester
d. phosphate
e. disulfide
16. Cri-du-chat syndrome is caused by which type of chromosomal mutation?
a. deletion
b. duplication
c. translocation
d. transversion
e. inversion
17. During replication, the role of DNA primase is to
a. add nucleotide to the growing DNA chain
b. synthesize a short chain for RNA
c. untwist the double helix at the origin of replication
d. relax the super coiling of the double helix
e. synthesize the primo some
18. A(n) ____________ inversion involves the Centro mere
a. chromocentric
b. paracentric
c. epicentric
d. percentric
e. concentric
19. Which of the following substances mutates DNA by intercalating between adjacent base pairs?
a. methyl methane sulfonate
b. all of these
c. nitrous acid
d. 2-amino urine
e. acridine orange
20. A molecule of RNA is always
a. double stranded
b. helical
c. nonparallel
d. all of these
e. none of these
21. Mutagenesis of cells using radiation or a chemical intercalating agent could be used to create __________ mutations in a region of DNA.
a. random
b. both random and site-specific
c. site-specific
22. In Griffiths’s tranformation experiments, the mice died when they were injected with
a. living, no virulent bacteria
b. living, virulent bacteria
c. heat-killed, no virulent bacteria
d. living, nonvirulent bacteria
e. both B and D
23. A monoploid human cells
a. shows only the excessive phenotype of all these genes
b. would be functionally impaired
c. is normal
d. would not survive
24. Gametes containing an abnormal number of chromosomes may occur as a result of
a. paracentric inversion
b. reciprocal translocation
c. disjunction of chromosomes
d. unequal crossing over
25. DNA may be altered as a result of _____________ events that occur normally in cells
a. depurination
b. deamination
c. depyrimidation
d. all of the above
e. none of the above
26. Which enzyme prevents DNA from tangling up as the replication fork migrates during replication?
a. DNA polymerase I
b. DNA helicase
c. topoisonmerase
d. DNA polymerase III
e. DNA gyrase
27. Which of the following enzymes play an important role in DNA replication?
a. DNA helicase
b. DNA ligase
c. DNA primase
d. all of them
e. DNA polymerase III
28. A mutation gene sustains a mutation that restores the original phenotype, This is a
a. frame shift mutation
b. transversion
c. reversion
d. transition
e. forward mutation
29. A dicentric chromosome has two
a. telomeres
b. mutations
c. arms
d. centromeres
30. Which type of chromosomal mutation cannot revert to the wild-type state
a. duplication
b. deletion
c. translocation
d. both A and C
e. all of them
31. Translation of histone mRNAs occurs during which phase of the eukaryotic cell cycle?
a. M
b. G1
c. G2
d. S
e. all of these
32. After removal of the RNA primers, Okazaki fragments are joined through a reaction that involves which enzyme?
a. RNA polymerase
b. DNA helicase
c. DNA polymerase
d. DNA primase
e. DNA ligase
33. Which of the following is required for the synthesis of DNA during replication?
a. DNA polymerase
b. magnesium ions
c. all of them
d. template DNA
e. dNTPs
34. Most of the genome of an active cell consists of
a. heterochromatin
b. histochromatin
c. poluchromatin
d. euchromatin
35. In eukaryotes, DNA replication begins,
a. a single origin of replication on each chromosome
b. a single origin of replication on each chromosome
c. multiple origins of replication on each chromosome
d. all of the above
e. none of the above
36. A human cell contains 2 sets of 24 chromosomes is
a. euploid
b. haploid
c. polyploid
d. aneuploid
37. Pseudodominance occurs as a result of which type of mutation?
a. translocation
b. duppolication
c. all of these
d. point mutation
e. deletion
38. The enzymatic activity of a telomerase is best described as a
a. none of these
b. polymerase
c. ligase
d. reverse transcriptase
e. topoisomerase
39. A Barr body is an example of
a. constitutive heterochromatin
b. facultative heterochromatin
c. facultative euchromatin
d. constitutive euchromatin
40. An addition or deletion of one or two base pairs in a gene causes a ____________ mutation
a. Transition
b. frameshift
c. nonsense
d. transversion
e. neutral
41. A heterozygous chromosomal inversion can be detected
a. by cytogenetic observation of loops in chromosomes
b. through genetic studies indicating a decrease in the frequency of recombination between genes
c. by observing a decrease in the number of viable progeny following genetic crosses
d. all of the above
42. The mutagen 5-bromouracil is an analog of which base?
a. adenine
b. threonine
c. thymine
d. cystosine
e. uracil
43. A mutation that changes a codon from one that represents an amino acid to one that signals a chain termination is a ______________ mutation.
a. neutral
b. missense
c. frame shift
d. nonsense
44. A chromosomal mutation that results in an increase in the amount of DNA is a(n)
a. duplication
b. inversion
c. deletion
d. both A and C
e. all of the above
45. Prior to replication, the DNA double helix must be untwisted by which type of enzyme?
a. topoisomerase
b. ligase
c. polymerase
d. helicase
e. primase
46. In his transformation experiments, Griffiths used cultures of which bacterium?
a. Sacchromyces cerevisiae
b. Escherichia coli
c. Streptococcus pneumoniae.
d. Bacillus cereus
e. Eneterococcus faecalis
47. A mutation changes a codon from a UCG to a UAG. This is a ____________ mutation?
a. point
b. nonsense
c. silent
d. both A and B
e. all of the above
48. In eukaryotes, DNA replication
a. is initiated at several sites on chromosomes
b. occurs bidirectional
c. is semidiscontinuous
d. all of the above
e. none of the above
49. Which of the following bacteria are used in the Ames test?
a. Pseudomonas aeruginosa
b. Escherichia coli
c. Vibrio cholera
d. Salmonella typhimurium
e. Rickettsia rickettsii
50. Which of the following changes represents a missense mutation?
a. UGA (stop) to UAG (stop)
b. AAA (lysine) to AGA (arginine)
c. UUU (phenylalanine) to UAA (stop)
d. AUG (methionine) to UGA (stop)
e. AAA (lysine) to AAG (lysine)
Explanation / Answer
1. Option E.
This is because all these events will cause changes in the genetic sequence and ultimately alter the protein. This change in protein structure will prevent it from delivering a normal function. Therefore, they all can cause cancer.
2. Option B.
It is a molecule which looks similar to uracil. The only difference is that it has a bromine. It can be incorporated into the DNA in place of thymine and thus cause mutation.
3. Option E.
The energy from UV radiations can induce the formation of covalent bonds between the two adjacent bases. And this could be either cysteine or thymine. In case of thymine, its called as thymine dimer.
4. Option A.
Heterochromatin region is that area of the genome which is packed very closely and not accessible to the transcriptional machinery and thus don't code for any protein. Telomere is one such region along with centromeres.
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