1. The objective lens in a microscope forms ________ image.A. Small invertedB. Small realC. Enlarged invertedD. Enlarged real2. The total magnification is calculated by ________the objective and eyepiece

magnifications.A. DividingB. MultiplyingC. SubtractingD. Adding3. Ideally a microscope should beA. Para focalB. BifocalC. Trifocal4. PARAFOCAL meansA. the image should remain in focus when objectives are changedB. the image should always be invertedC. the image must be dark5. _______ is the ability of a lens to separate or distinguish between small objects that are

close together.A. SeparationB. ResolutionC. Perfection6. The minimum distance (d) between two objects that reveals them as separate entities is

given by the ______equation.A. Lulu.B. BifidusC. Abbe7. As d becomes smaller, the resolution ________.A. DecreasesB. IncreasesC. Becomes zero8. The numerical aperture is________.A. Nsin(theta)B. Ncos(theta)C. Ntan(theta)9. Light that strikes the microorganism after passing through a condenser isA. Spherically shapedB. Rectangular shapedC. Cone shaped10. sin (theta) cannot be greater thanA. 2B. 3C. 111. What is used to increase the refractive index of microscope

A. Yellow sulphur solutionB. Colorless immersion oilC. Regular motor oil12. Optical theory underlying microscope design was developed by the German physicist A. Ernst AbbeB. William hunterC. John dutch13. no lens working in air can have a numerical aperture greater than A. 1.00B. 7.00C. 9.0014. The final observed image is calledA. RealB. VirtualC. Imaginary15. The resolution of a microscope depends upon the numerical aperture of its ________as

well as that of the objective.A. CondenserB. FillerC. Subjective16. Most microscopes have a condenser with a numerical aperture between A. 3.2 and 5.6B. 1.2 and 1.4C. 6.7 and 4.017. The condenser numerical aperture will not be much above about __________ unless the

top of the condenser is oiled to the bottom of the slideA. 0.4B. 0.8C. 0.6D. 0.918. At best, a bright-field microscope can distinguish between two dots around ______apartA. 0.2 um apartB. 0.6 um apartC. 0.1 um apart19. At best, a bright-field microscope can distinguish between two dots size of a A. VirusB. FugusC. Bacterium20. Normally a microscope is equipped with three or four objectives ranging in magnifying

power A. 5 to500XB. 10 to 100XC. 3 to 100XD. 4 to 100X21. The ___________ distance of an objective is the distance between the front surface of

the lens and the surface of the cover glass

A. WokingB. ActiveC. Accurate22. The useful limit of magnification is about _______ times the numerical aperture of the

objective lens.A. 2000B. 3000C. 5000D. 100023. A microscope equipped with a ______ mirror between the light source and the specimen

illuminates the slide with a fairly narrow cone of light and has a small numerical aperture.A. CocaveB. ConvexC. Double24. a large light-gathering lens used to project a wide cone of light through the slide and into

the objective lens isA. full condenserB. substage condenserC. simple condenser25. A hollow cone of light is focused on the specimen in such a way that ___________

and___________ rays do not enter the objectiveA. unreflected and unrefractedB. reflected and refracted26. normally a microscope is equipped with __________ number of objectives.A. 7 to 8B. 9 to 12C. 1 to2D. 3 to 427. The resolution of a microscope depends upon the __________ aperture of its condenser

as well as that of the objective.A. SubjectiveB. Numerical28. Living, unstained cells and organisms can be observed by simply changing the way in

which they areA. IlluminatedB. Filled29. In dark field microscopy, the dark surface isA. BackgroundB. ObjectC. Lens30. Considerable internal structure is often visible in larger _________ microorganismsA. EukaryoticB. Prokaryotic31. The dark-field microscope is used to identify bacteria which areA. ThinB. Thick

C. Distinctively shapedD. Both a and c32. Treponema pallidum is the causative agent of A. SyphilisB. t.bC. herpes simplex33. Microorganisms often must be _________before observation to increase contrast and

create variations in color between cell structures.A. WashedB. fixed and stainedC. killed34. A __________ microscope converts slight differences in refractive indexA. SimpleB. Phase contrastC. Dark fieldD. Electronic35. The condenser of a phase-contrast microscope has an annular stop, an opaque disk with a

thin transparent ring, which produces a _________ of lightA. SmearB. Hollow coneC. Full cone36. As this cone passes through a cell, some light rays are bent due to variations in A. DensityB. WeightC. Mass37. The simplest way to convert a microscope to dark-field microscopy is to place

____________ underneath the condenserlens system.A. S light field stopB. a dark-field stop38. Treponema pallidum is best observed byA. Dark field microscopeB. Phase contrast microscopeC. Simple microscope39. The condenser of a phase-contrast microscope has an _______________, an opaque disk

with a thin transparent ring, which produces a hollow cone of lightA. Full stopperB. Middle stopperC. Annular stop40. Objectives with large numerical apertures and great resolving power have __________

working distances.A. LargeB. ShortC. Zero41. Light cone passes through a cell, some light rays are bent due to variations in density and

refractive index within the specimen and are retarded by about________wavelength.A. 1/3

B. ¼C. 1/542. The angle of the cone of light that can enter a lens depends on the A. refractive indexB. focal length43. At best, a bright-field microscope can distinguish between two dots around ______apartA. 0.2 um apartB. 0.6 um apartC. 0.1 um apart44. At best, a bright-field microscope can distinguish between two dots size of a A. VirusB. FugusC. Bacterium45. The limits set on the resolution of a light microscope can be calculated using the A. Abbe equationB. Dutch equationC. Fullers equation46. In dark phase contrast microscopy, the dark surface isA. BackgroundB. ObjectC. Lens47. Phase-contrast microscopy is especially useful for studying A. microbial motility, B. determining the shape of living cells, C. detecting bacterial components D. all of the above48. Phase contrast microscopes also are widely used in studying _________cellsA. ProkaryoticB. Eukaryotic49. Direct light rays are advanced 1/4 ___________ as they pass through the phase ring.A. WavelengthB. Refractive index50. Most diffracted rays of light pass through phase plate unchanged because they miss the A. Bundle tingB. phase ringC. tight ring51. the DIC microscope is similar toA. simple microscopeB. phase contrast microscope52. the DIC microscope is similar to phase contrast microscope because both involve

calculation based onA. refractive indicesB. thicknessC. both53. In DIC, Two beams of plane polarized light at ______angles to each other are generated

by prisms.

A. 95 DEGREESB. 90 DEGREESC. 75 DEGREES54. In DIC, Two beams of plane polarized light at 90 degree angles to each other are

generated by _______.A. GlassB. Prisms55. In DIC, ______ beams of plane polarized light at 90 degree angles to each other are

generated by prisms.A. 2B. 3C. 4D. 656. In one design of DIC, the object beam passes through the specimen, while the reference

beam passes through a _____ area of the slide.A. OpaqueB. Clear57. In one design of DIC, the _______ beam passes through the specimen, while the ______

beam passes through a clear area of the slide.A. Object and referenceB. Reference and object58. In one design of ________, the object beam passes through the specimen, while the

reference beam passes through a clear area of the slide.A. Dic microscopeB. Simple microscopeC. Phase microscope59. A live, unstained specimen appears brightly colored and_______-dimensional in DIC.A. 2B. 3C. 460. A live, unstained specimen appears brightly colored and three-dimensional in ________.A. DICB. Dark phase61. A live, _______ specimen appears brightly colored and three-dimensional in DIC.A. Stained B. Unstained62. An object also can be seen because it actually _____ light, and this is the basis of

fluorescence microscopy.A. EmitsB. Absorbs63. An object also can be seen because it actually emits light, and this is the basis of

__________microscopy.A. DICB. Fluorescence64. When some molecules absorb radiant energy, they become ________ and later release

much of their trapped energy as light.

A. ExcitedB. Dull65. When some molecules absorb radiant energy, they become excited and later release much

of their trapped energy as _________.A. SoundB. PollutionC. Light66. When some molecules absorb radiant ________, they become excited and later release

much of their trapped energy as light.A. SourceB. energy67. Any light emitted by an excited molecule will have a _______ wavelength than the

radiation originally absorbed.A. SmallerB. FullerC. Longer68. Any light ______ by an excited molecule will have a longer wavelength (or be of lower

energy) than the radiation originally _______.A. Emitted and absorbedB. Absorbed and emitted69. ___________ light is emitted very quickly by the excited molecule as it gives up its

trapped energy and returns to a stable state.A. FluorescentB. Blue70. Fluorescent light is ________ very quickly by the excited molecule as it gives up its

trapped energy and returns to a stable state.A. EmittedB. Absorbed71. Fluorescent light is emitted very quickly by the excited molecule as it gives up its trapped

energy and returns to a _______state.A. StableB. Excited72. The fluorescence microscope exposes a specimen to ______________________ and

forms an image of the object with the resulting fluorescent light.A. ultraviolet, B. violet, C. blue lightD. all of the above73. for fluorescence microscope the specimens have been stained with dye molecules, calledA. fluorochromesB. bichromesC. dichromes74. A barrier filter positioned after the objective lenses removes any remaining ultraviolet

light, which could damage A. The lensB. the viewer’s eyes

75. A barrier filter positioned after the objective lenses removes any remaining ________ light, which could damage the viewer’s eyes

A. UVB. MicrowavesC. Blue76. The fluorescence microscope has become an essential tool in medical _______ and

microbial_________.A. Microbiology, EcologyB. Chemistry, biologyC. Ecology, biology77. The ________ microscope has become an essential tool in medical microbiology and

microbial ecology.A. DICB. Fluorescence78. In ecological studies the fluorescence microscope is used to observe microorganisms

stained with A. fluorochrome-labeled probesB. fluorochromes such as acridine orangeC. DAPID. All of the above79. Excitor filter allows only ______wavelength light throughA. SmallB. Large80. Live or dead bacteria can be distinguished through____________microscopeA. DICB. Fluorescence81. DAPI is a A. Dna specific stainB. Rna specific stain82. Organisms are fixed and stained to A. Increase visibility, B. accentuate specific morphological features, C. preserve them for future studyD. all of the above83. Organisms are ____________ to Increase visibility, accentuate specific morphological

features, and preserve them for future study.A. Fixed and stainedB. PreservedC. Calculated84. The stained cells seen in a microscope should resembleA. Living cellsB. Old cellsC. Fertilized cells85. __________ is the process by which the internal and external structures of cells and

microorganisms are preserved and fixed in position.A. Staining

B. FixationC. Enlargement86. Fixation is the process by which the ________ and ________ structures of cells and

microorganisms are preserved and fixed in positionA. Full and partialB. External and internal87. Fixation ________the enzymesA. KillB. ActivatesC. Inactivates88. Fixation _____________cell structuresA. ToughenB. SoftenC. Distorts89. During fixation a micro organism is usually A. KilledB. Kept alive90. During fixation a micro organism is usually A. Kept aliveB. Attached to slide91. There are ________types of fixationA. 6B. 7C. 3D. 292. Basic dyes include A. methylene blue, B. basic fuchsin, C. crystal violet,D. safranin,E. malachite greenF. All of the above93. Acid dyes includeA. methylene blue, B. basic fuchsin, C. crystal violet,D. safranin,E. malachite greenF. none of the above94. basic dye includesA. eosin,B. rose BengalC. acid fuchsinD. none of the above95. acid dyes includeA. eosin,

B. rose BengalC. both96. Chemical fixatives penetrate cells and react with cellular componentsA. Proteins and lipidsB. Lipids and soloids97. Common fixative mixtures contain such components as ethanol, acetic acid, mercuric

chloride, formaldehyde, and_____________.A. GlutaraldehydeB. Sulphuric acid.98. Common fixative mixtures contain such components as ethanol, acetic acid, mercuric

chloride, __________, and GlutaraldehydeA. FormaldehydeB. Sulphuric acid99. Common fixative mixtures contain such components as ethanol, acetic acid, _________,

formaldehyde and glutaraldehyde.A. Mercuric chlorideB. Sulpluric acid100. Excitor filter allows only ______wavelength light throughC. SmallD. Large

101. A slippery outer covering in some bacteria that protects them from phagocytosis by host cells is

A. capsule b. cell wall c. flagellum d. peptidoglycan

102. When flagella are distributed all around a bacterial cell, the arrangement is calleda. polar b. random C. peritrichous d. encapsulated

103. A shiny, sticky colony of Streptococcus pneumoniae is likely to beA. encapsulated and pathogenic c. nonencapsulated and nonpathogenicb. nonencapsulated and pathogenic d. encapsulated and nonpathogenic

104. A bacterial cell wall does all of the following excepta. gives shape and rigidity to the cell b. is the site of action for some antibioticsc. is associated with some symptoms of disease D. protects the cell from phagocytosis

105. The minimum distance at which a microscope is capable of distinguishing two points as separate is its

a. magnification b. illumination C. resolving power

106. A Gram negative cell wall is __________ than a Gram positive one.a. thicker B. thinner

107. Because penicillin prevents peptidoglycan synthesis, it is more effective on _______________ cells.

A. Gram positive b. Gram negative

108. Flagella and pili are made ofa. lipids b. carbohydrates c. nucleic acids D. protein

109. The genetic information of bacteria is stored in _______, in one circular chromosome located in the cytoplasm.

A. DNA b. protein c. phospholipids d. RNA

110. Differences between eukaryotic and prokaryotic cells include all of the following except

a. eukaryotic cells have mitochondria c. prokaryotic cells have more complex cell wallsb. eukaryotic cells have cilia and flagella with complex structure D. prokaryotic cells have no genetic material

111. The fact that viruses are obligate intracellular parasites means that they require a ____________________ for reproduction.

a. culture dish B. host cell c. phenol red broth d. secondary virus

112. One way to determine the size, cell morphology and grouping of bacterial cells is to use a __________ technique.

a. streak plate b. phenol red C. simple stain d. nutrient broth culture

113. Cloudiness is a sign that bacteria have grown in a -_______________ after inoculation and incubation.

a. streak plate B. tube of nutrient broth c. Gram stain d. simple stain

114. The bacterial envelope includes all of the following structures excepta. capsule b. cell wall c. cell membrane D. endospore

115. All of the following structures of bacteria contain (or are made of) protein exceptA. plasmids b. ribosomes c. pili d. cell membrane

116. Which of the following contains polysaccharide?A. Gram negative cell wall b. pili c. flagella d. plasmids

117. Which of the following contains DNA?a. Gram positive cell wall b. capsule c. pili D. plasmids

118. In a Gram stain procedure, bacteria with Gram positive cell walls decolorize less easily than those with Gram negative cell walls.  A. true b. false119. The cell wall type that has less peptidoglycan is

A. Gram negative b. Gram positive

120. The cell wall type that is most vulnerable to the action of penicillin isa. Gram negative B. Gram positive

121. When flagella are located around the entire bacterial cell, the arrangement is called

a. polar b. random c. bipolar D. peritrichous

122. An encapsulated cell will reproduce to form colonies that appear

a. nonpathogenic b. translucent c. pink D. smooth

123. Endospore are all of the following except ___________ as compared to vegetative cells.

a. more likely to survive treatment with disinfectants b. more resistant to stainingC. more likely to die in nutritionally poor conditions d. more resistant to temperature changes

124. Phagocytosis of the bacteria that cause pneumonia is ____ likely if the bacteria are protected by a capsule.

A. less b. more

125. If you use a visible light microscope to examine a live culture of a bacterium possessing flagella, you will be able to see the flagella moving the bacteria.

a. true B. false

126. In what phase of the growth curve is/does a culture most sensitive to antibiotics? A. a,maximum B. exponential growth, C. c,stationary

127. Most human pathogens prefer temperatures near that of the human body. They are called

a. psychrophiles b. thermophiles C. mesophiles d. halophiles

128. The optimum temperature for an organism is the one at whichA. it grows with the shortest generation timeb. it has the longest time between cell divisionsc. it is near one extreme of its range of tolerated temperaturesd. its enzymes begin to denature

129. The breakdown of glucose to pyruvate is called glycolysis and produces most of the ATP available from the glucose molecule.

a. true B. false

130. Energy is stored in the ATP (adenosine triphosphate) molecule in itsa. sugar portion b. adenine portion C. third phosphate bond

131. Organisms that ferment glucose may produce any of the following end products except

a. lactic acid b. propionic acid c. alcohol D. oxygen

132. Fluorescent light is ________ very quickly by the excited molecule as it gives up its trapped energy and returns to a stable state.

C. EmittedD. Absorbed

133. Fluorescent light is emitted very quickly by the excited molecule as it gives up its trapped energy and returns to a _______state.C. StableD. Excited

134.The fluorescence microscope exposes a specimen to ______________________ and forms an image of the object with the resulting fluorescent light.

E. ultraviolet, F. violet, G. blue lightH. all of the above

135. for fluorescence microscope the specimens have been stained with dye molecules, called

D. fluorochromesE. bichromesF. dichromes

136. A barrier filter positioned after the objective lenses removes any remaining ultraviolet light, which could damage

C. The lensD. the viewer’s eyes

137. A barrier filter positioned after the objective lenses removes any remaining ________ light, which could damage the viewer’s eyes

D. UVE. MicrowavesF. Blue

138. The fluorescence microscope has become an essential tool in medical _______ and microbial_________.

D. Microbiology, EcologyE. Chemistry, biologyF. Ecology, biology

139. The ________ microscope has become an essential tool in medical microbiology and microbial ecology.

C. DICD. Fluorescence

140. In ecological studies the fluorescence microscope is used to observe microorganisms stained with

E. fluorochrome-labeled probes

F. fluorochromes such as acridine orangeG. DAPIH. All of the above

141. Human cheek cells are commonly stained witha. methylene blueb. safraninc. acetocarmined. eosine

 

142. Definite shape of cell is seen in case ofa. animal cellb. plant cellsc. both animal and plant cellsd. neither animal nor plant cells

 

143. Coverslip is put on the mounted material on a slide very gently toa. avoid oozing of stainb. avoid oozing of glycerinec. avoid entry of air bubblesd. avoid the crushing of mounted materials

144. Name the stain which is commonly used to study plant cellsa. methylene blueb. cotton bluec. safranind. acetocarmine

 

145. Plant cells generally havea. No vacuoles at allb. all equal sized vacuolesc. small but large number of vacuolesd. big but less number of vacuoles

 

146. We generally mount the material on slidea. on left side of slideb. on right side of slidec. in the centred. both (a) and (b)

147. Cells are focused in microscope undera. 40Xb. 100Xc. 10Xd. any of these

148. In animal cheek cells, nucleus is generally locateda. near the plasma membraneb. on one sidec. in the centred. any where in the cell

 

149. In plant cell, nucleus is generally placeda. in the centreb. on one side of the cellc. attached to cell membraned. on one corner of the cell

150.Temporary mount of a tissue is made ina. waxb. alcoholc. xylened. glycerine 

 

151. The outermost covering of a plant cell isa. cell wallb. nuclear membranec. plasma membraned. middle lamella

 

152. The organelle not present in human cheek cell isa. nucleusb. mitochondriac. cell membraned. chloroplast

 

153. The outer most layer of human cheek cell isa. cell wallb. nuclear membranec. plasma membraned. middle lamella

 

154. The shape of onion peel cells taken for observation under microscope isa. roundb. ellipticalc. rectangulard. round

155. The shape of nucleus in a plant cell isa. roundb. ellipticalc. rectangulard. triangular

 

156. The number of lenses in a compound microscope isa. 2b. 1c. 3d. 4

157. During observation of an onion peel, cells are first seen undera. high powerb. low powerc. medium powerd. none of the above

 

158. To prepare a mount of human cheek cell, the sample is collected froma. outer side of cheek with a bladeb. inner side of cheek with a bladec. outer side of cheek with a toothpickd. inner side of cheek with a toothpick.

159. Which one of the following cell constituents cannot be seen while observing a human cheek cell?a. nucleusb. cell wall

c. cytoplasmd. cell membrane

 

160. To observe cells in an onion peel, we must prepare the slide by mounting on ita. crushed pulp of onionb. dry scale leafc. green leaf of oniond. thin layer of fleshy onion

 

161. The cellular component not seen under a compound microscope while observing onion peela. chromosomeb. cell wallc. nucleusd. cytoplasm

 

162. Cells are stained toa. nourish the cellb. highlight the cell organellesc. make the cell turgidd. help in cell multiplication

 

163. human cheek cell stained in methylene blue and mounted in glycerine were observed under a compound microscope. The components of cell which would be seen area. cell wall, cytoplasm, nucleusb. plasma membrane, cytoplasm, nucleusc. plasma membrane, cytoplasm, nucleus, mitochondriad. plasma membrane, nucleus, mitochondria lysosomes

 

164. Magnifying power of a microscope is calculated bya. multiplying the power of objective lens and eye pieceb. multiplying the power of objective lens with the distance between the objective lens and the specimenc. adding up the power of objective lens and eye pieced. subtracting the power of objective lens from that of eye piece.

 

165. Glycerine is used to prepare a temporary mount of a tissue due to the following reason

a. to colour the specimenb. to avoid drying up of the specimen quicklyc. to avoid entry of air bubblesd. none of the above

 

166.The less stained central part of onion peel cell isa. nucleusb. cytoplasmc. vacuoled. cell wall

 167.A light microscope has an objective lens with a magnification of 40x and an ocular lens with a magnification of 10x. What is the total magnification of the image?A.40xB.50xC.400xD.450x168.Which of the following does not contribute to the resolution attainable by a microscope?A.the wavelength of the lightB.the magnification of the objective lensC.the refractive index of the material between the specimen and the lensD.the numerical aperture of the lens169.Under which of the following conditions would the visibility of an object under a microscope be lowest?A.The object has the same refractive index as does the medium.B.The object and the background each bend light differently.C.The object diffracts some, but not all, of the light rays that hit it.D.The object absorbs some, but not all, of the light rays that hit it.170.You are interested in reconstructing the three-dimensional shape of chromosomes in living cells that are in the process of mitosis. Which microscopic technique will you choose?A.freeze-fracture microscopyB.confocal scanning microscopyC.light microscopyD.scanning electron microscopy171.You wish to find the intracellular compartments that contain high calcium concentrations. Which of the following microscopic techniques will you choose?A.fluorescence microscopyB.polarization microscopyC.phase-contrast microscopyD.transmission electron microscopy172.Why are transmission electron micrographs never in color?A.Cellular structures have no color. They are all shades of gray.B.Color micrographs would be too expensive.C.Color film has not yet been invented.D.The photographic film detects electrons that are transmitted through the specimen rather than the different wavelengths of light that determine color.

173You think you might have discovered a new organelle using electron microscopy, but it might be an artifact of your technique. What might you do to prove it is real?A.Look for the structure in many similarly prepared specimens from the same source.B.Look for the structure in many similarly prepared specimens from different sources.C.Look for the same structure in specimens prepared using different staining protocols.D.Look for the same structure in specimens prepared using different (or no) fixatives.174.The half-life of tritium is 12 years. If you had some tritium and kept it for 24 years, what percentage of your original radioactive sample would be left?A.12%B.25%C.75%D.none175.You want to know if a culture of cells is in the process of DNA synthesis. You incubate your cells in the presence of radioactive thymidine to see if it is being incorporated into the DNA. What is the best technique to detect the labeled deoxynucleotide in nuclear DNA?A.autoradiographyB.polyacrylamide gel electrophoresisC.agarose gel electrophoresisD.two-dimensional gel electrophoresis176.The major difference between defined and undefined cell media used in cell culture isA.undefined medium is a recent development in cell culture technology.B.undefined medium is completely artificial.C.defined medium includes serum, lymph or other fluids from living sources.D.defined medium is free of serum, lymph or other fluids from living sources.177.Which of the following would be the least promising source of cells for a primary cell culture?A.embryonic tissueB.actively growing malignant tumor tissueC.adult rat brain tissueD.plant protoplasts178.You have homogenated and fractionated rat liver cells using differential centrifugation. Which fraction would have the fewest mitochondria?A.whole homogenate before any centrifugation stepsB.the supernatant that results after the first low-speed centrifugation stepC.the supernatant that results after a high-speed ultracentrifugation stepD.None of the above fractions would have any mitochondria.179.Which type of column chromatography separates proteins on the basis of molecular weight?A.ion-exchange chromatographyB.gel filtration chromatographyC.affinity chromatographyD.isoelectric focusing180.In gel electrophoresis, the tracking dye moves:A.more slowly than all the different molecules of the sample.B.at the same rate as all the different molecules of the sample.C.more quickly than all the different molecules of the sample.D.not at all.181.Nucleic acid hybridization can be used as a measure of evolutionary relationships between species. Of the following statements about the DNA of related species, which is

true?A.Closely related species form hybrid DNAs with relatively low melting temperatures.B.Closely related species form hybrid DNAs with relatively high melting temperatures.C.There is no correlation between DNA hybrid melting temperature and relatedness of species.D.One cannot create DNA hybrid molecules from DNAs of closely related species.182.DNA fragments and DNA probes are to Southern blotting as  --  ?   --  are to Northern blotting.A.DNA fragments and RNA probesB.RNA fragments and RNA probesC.RNA fragments and DNA probesD.protein fragments and DNA probes183.The role of the vector DNA in DNA cloning is to:A.identify the source of DNA as foreign.B.identify the host cell that has taken up the one specific gene of interest.C.make the foreign DNA susceptible to digestion with endonucleases.D.carry the foreign DNA into the host cell.184.Why does one need to make replica plates when screening for a specific DNA sequence among a large number of recombinant bacterial colonies?A.It may take several tries to positively identify the specific sequence of interest.B.The screening process requires several different steps, each of which must be done on a new colony of recombinants.C.One wants a living culture of recombinant cells available after screening, a process that destroys the cells.D.It is good science to replicate all experimental results.185.What is a “gene gun”?A.a gun that fires DNA-coated pellets into plant cellsB.a new technique using “explosively fast” enzymes to form recombinant DNAC.a weapon of mass destruction that exploits recombinant DNA technology for warfareD.none of the above186.Why are heat-stable DNA polymerases from thermophilic bacteria required for the polymerase chain reaction?A.The heat-stable forms are the only ones that recognize all four deoxyribonucleotides.B.These enzymes amplify DNA in a reasonable amount of time.C.These enzymes are the most readily available forms of DNA polymerase in the world.D.These enzymes are stable enough to withstand the temperatures required to melt DNA.