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Biotechnology Multiple Choice Questions

1) The restriction endonuclease has a defense mechanism in the bacterial system against foreign DNA such as viruses. But how can it protect its DNA?

  1. precisely in the middle of the chain
  2. anywhere in the chain
  3. the ends of the chain
  4. only within the polynucleotide chain, not at the ends

Answer: D [only within the polynucleotide chain, not at the ends]

Description: The cleavage is done within the polynucleotide chain and not at the ends. The enzyme which cuts the sequence at the ends is known as an exonuclease.


2) The restriction endonuclease has a defense mechanism in the bacterial system against foreign DNA such as viruses. But how can it protect its DNA?

  1. By methylation of bacterial DNA by restriction enzyme
  2. By methylation of foreign DNA by restriction enzyme
  3. By phosphorylation of bacterial DNA by restriction enzyme
  4. By phosphorylation of foreign DNA by restriction enzyme

Answer: A [ By methylation of bacterial DNA by restriction enzyme ]

Description: The bacterial DNA is methylated by restriction enzyme, and thus, now it is not recognized by the restriction endonuclease. Thus methylation prevents the restriction endonuclease from cutting its DNA.


3) Even after replication, how the modified DNA remains protected?

  1. It remains protected because of the conservative mode of replication
  2. It remains protected because of the semi-conservative mode of replication
  3. The mode of replication has no role to play in the protection
  4. It is again modified after replication

Answer: B [It remains protected because of the semi-conservative mode of replication]

Description: Because of the semi-conservative replication model, one of the DNA strands remains methylated even after replication. One methylated strand is sufficient for protecting cleavage by a restriction endonuclease.


4) After cleaving the sequence, the nature of the ends created by the type II endonuclease is __________

  1. The ends created are always single-stranded
  2. The ends created are always double-stranded
  3. Either the ends are single-stranded, or they are double-stranded
  4. One end is single-stranded, and one end is double-stranded

Answer: C [Either the ends are single-stranded or they are double stranded]

Description: Either the ends are both double-stranded or are both single-stranded. The double-stranded ends are blunt, whereas the single-stranded ends are sticky.


5) If all the nucleotides are present with equal frequencies and at random, what are the chances of having a particular four nucleotide long motif?

  1. 1/256
  2. 1/64
  3. 1/16
  4. 1/8

Answer: A [ 1/256 ]

Description: There are four nucleotide bases present in a DNA sequence A, T, C, and G. If the bases are present with equal frequency and at random, the chances of having a particular four long nucleotide motif is 1/ (4*4)= 1/256.


6) The specificity of an enzyme is affected by the concentration of buffer used. This phenomenon is termed as:

  1. star activity
  2. specificity elevation
  3. concentration gradient effects
  4. diamond activity

Answer: A [star activity]

Description: As the buffer concentration is varied, an enzyme's specificity is lost, and this phenomenon is termed star activity. We mean that a particular set of sequences can be identified by loss of specificity instead of a particular sequence.


7) Which of the following is the correct terminology of a restriction enzyme obtained from the first activity of strain R of Escherichia coli?

  1. EcoR1
  2. EscRI
  3. EcorI
  4. EcoRI

Answer: D [EcoRI]

Description: The first letter is the first letter of the genus, and the next two letters are the first two letters of the species. They are then followed by the strain and the activity from which they are isolated. The activity is represented in Roman numerals.


8) If only one bond is broken in the sugar-phosphate backbone, it is called as ___________

  1. gap
  2. nick
  3. break
  4. leakage

Answer: B [nick]

Description: If only one bond is broken in the sugar-phosphate backbone, it is termed as nick. If several nucleotides are missing, it is termed a gap. Ligation reactions can seal nick, but a ligation reaction can't seal the gap.


9) The ligation reaction is more efficient, in which case?

  1. Blunt end ligation
  2. Sticky end ligation
  3. Both have the same efficiency
  4. Depends on the reaction conditions

Answer: B [Sticky end ligation]

Description: Sticky end ligation is generally more efficient than blunt-end ligation. It is so because sticky end ligation is carried out because of complementary base pairing.


10) The sticky ends are held together by which type of bonds?

  1. Hydrogen bond
  2. Covalent bond
  3. Ionic bond
  4. Van-der-Waal forces

Answer: A [Hydrogen bond]

Description: The sticky ends are held together by the hydrogen bonds. Hydrogen bonds are weak and can easily be broken.


11) If a ligation reaction is being carried out and recircularization is observed, which type of reaction is being carried out?

  1. Intramolecular
  2. Intermolecular
  3. Both observe recircularization equally
  4. Recirculation is not possible in any of the cases

Answer: A [Intramolecular]

Description: Recircularization is the phenomenon of joining the ends of the same molecule. It happens in the case of the intramolecular ligation reaction.


12) Topoisomerase is also an enzyme that is used for carrying out ligation. The correct statement for topoisomerase is?

  1. They act only on double-stranded molecules
  2. They alter the degree of supercoiling of DNA molecules
  3. They are less effective than conventional DNA ligase
  4. There are three types of topoisomerases

Answer: B [They alter the degree of supercoiling of DNA molecules]

Description: Topoisomerases change the degree of supercoiling of both single and double-stranded DNA molecules. There are two types of topoisomerases, I and II. I is responsible for altering single-stranded molecules and type II for converting double-stranded molecules. They are more effective than conventional DNA ligases.


13) Topoisomerase is also an enzyme that is used for carrying out ligation. The correct statement for topoisomerase is?

  1. They act only on double-stranded molecules
  2. They alter the degree of supercoiling of DNA molecules
  3. They are less effective than conventional DNA ligase
  4. There are three types of topoisomerases

Answer: B [They alter the degree of supercoiling of DNA molecules]

Description: Topoisomerases alter the degree of supercoiling of both single and double-stranded DNA molecules. There are two types of topoisomerases, I and II. I is responsible for altering single-stranded molecules and type II for altering double-stranded molecules. They are more effective than conventional DNA ligases.


14) Transformation carried out using a particle gun is known as biolistic transformation. It falls under which category of transformation?

  1. Physical
  2. Chemical
  3. Electroporation
  4. Natural

Answer: A [Physical]

Description: The transformation carried out using a particle gun falls under the physical transformation category. The physical transformation uses some physical methods to carry out transformation.


15) Isolation of genomic DNA follows the same principles as obtaining plasmid from E. coli. Which of the following is not included in it?

  1. Cell lysis
  2. Removal of proteins
  3. Removal of chromosomal DNA
  4. Dissolving plasmid in water

Answer: D [Dissolving plasmid in water]

Description: Some basic steps are included in obtaining plasmid DNA from E. coli. Firstly, the cell is lysed, further removal of proteins and chromosomal DNA is done. A plasmid is obtained and collected but not in water. Also, further purification is done if necessary.


16) Adsorption onto a solid phase support followed by elution is used as an alternative for separation of which component?

  1. chromosomal DNA
  2. plasmid DNA
  3. RNA alone
  4. other impurities

Answer: B [ plasmid DNA ]

Description: This method is used for the separation of plasmid DNA. It is advantageous because it avoids phenol and removes RNA at times along with plasmid DNA.


17) Which of the following components bind to the solid column made of silica under high salt concentration?

  1. Proteins
  2. Polysaccharides
  3. Both proteins and polysaccharides
  4. Plasmid DNA

Answer: D [Plasmid DNA]

Description: Plasmid DNA binds to solid support made of silica and under high salt concentrations. A high salt concentration doesn't allow fewer polar molecules to bind, such as polysaccharides and proteins. The bonded DNA molecule is further eluted by using a low salt concentration.


18) Which of the following components settles at the bottom?

  1. RNA
  2. Proteins
  3. Nicked DNA
  4. Supercoiled DNA

Answer: A [RNA]

Description: The component settling at the bottom is RNA. And the proteins float on the free surface. The nicked DNA forms a band above the supercoiled form.


19) Which one of the following will travel fastest through the gel if the amount of DNA present is the same in all?

  1. Circular
  2. Supercoiled
  3. Nicked
  4. Supercoiled and circular will move at the same speed and faster than nicked

Answer: B [Supercoiled]

Description: The supercoiled form of DNA will travel the fastest. It is so because; the movement through the gel is based on the size. The smaller the molecule is, the less retarding force it experiences when it moves. Hence, supercoiled, which is having the smallest size, will move the fastest.


20) In the case of electrophoresis of single-stranded DNA or RNA, which type of gels are used?

  1. Renaturing
  2. Denaturing
  3. The routine agarose gel
  4. The routine polyacrylamide gel

Answer: B [Denaturing]

Description: In the case of single-stranded molecules, denaturing gels are used. If denaturing gels are not there, there are chances of forming secondary structures that hinder the movement of nucleic acids. Thus to avoid this, denaturing agents such as urea, etc., are added.


21) The ratio of a mass concentration of species A to the total mass density of the mixture is known as

  1. Concentration
  2. Mass Density
  3. Mole fraction
  4. Mass Fraction

Answer: D [ Mass Fraction ]

Description: It is defined as Mass Fraction.


22) The ratio of the number of moles of species A to the total number of moles of the mixture is known as

  1. Mole fraction
  2. Mass fraction
  3. Partial pressure
  4. Mass density

Answer: A [ Mole Fraction ]

Description: It is defined as na/n.


23) A binary mixture of oxygen and nitrogen with partial pressures in the ratio 0.21 and 0.79 is contained in a vessel at 300 K. If the total pressure of the mixture is 1 * 10 5 N/m2, find a molar fraction of nitrogen

  1. 0.79
  2. 0.21
  3. 0.23
  4. 0.13

Answer: A [ 0.79 ]

Description: The molar fraction is equal to the partial pressure.


24) A binary mixture of oxygen and nitrogen with partial pressures in the ratio 0.21 and 0.79 is contained in a vessel at 300 K. If the total pressure of the mixture is 1 * 10 5 N/m2, find the average molecular weight of the mixture

  1. 28.84
  2. 29.84
  3. 30.84
  4. 31.84

Answer: A [ 28.84 ]

Description: (0.21) (32) + (0.79) (28) = 28.84.


25) What is the value of emissivity for polished aluminum?

  1. 0.01
  2. 0.02
  3. 0.03
  4. 0.04

Answer: C [ 0.03 ]

Description: The emissivity of a material's surface is its effectiveness in emitting energy as thermal radiation.


26) The restriction endonuclease has a defense mechanism in the bacterial system against foreign DNA such as viruses. But how is it able to protect its DNA?

  1. By methylation of bacterial DNA by restriction enzyme
  2. By methylation of foreign DNA by restriction enzyme
  3. By phosphorylation of bacterial DNA by restriction enzyme
  4. By phosphorylation of foreign DNA by restriction enzyme

Answer: A [ By methylation of bacterial DNA by restriction enzyme ]

Description: The bacterial DNA is methylated by restriction enzyme, and thus now it is not recognized by the restriction endonuclease. Thus methylation prevents the restriction endonuclease from cutting its DNA.


27) Even after replication, how the modified DNA remains protected?

  1. It remains protected because of the conservative mode of replication
  2. It remains protected because of the semi-conservative mode of replication
  3. The mode of replication has no role to play in the protection
  4. It is again modified after replication

Answer: B [ It remains protected because of the semi-conservative mode of replication ]

Description: Because of the semi-conservative replication model, one of the DNA strands remains methylated even after replication. One methylated strand is sufficient for protecting cleavage by a restriction endonuclease.


28) After cleaving the sequence, the nature of the ends created by the type II endonuclease is __________

  1. The ends created are always single-stranded
  2. The ends created are always double-stranded
  3. Either the ends are single-stranded, or they are double-stranded
  4. One end is single-stranded, and one end is double-stranded

Answer: C [ Either the ends are single-stranded, or they are double-stranded ]

Description: Either the ends are both double-stranded or are both single-stranded. The double-stranded ends are blunt, whereas the single-stranded ends are sticky.


29) If all the nucleotides are present with equal frequencies and at random, what are the chances of having a particular four nucleotide long motif?

  1. 1/256
  2. 1/64
  3. 1/16
  4. 1/8

Answer: A [ 1/256 ]

Description: There are four nucleotide bases present in a DNA sequence A, T, C, and G. If the bases are present with equal frequency and at random, the chances of having a particular four nucleotide long motif is 1/ (4*4)= 1/256


30) Which one is having the lowest value of diffusivity?

  1. Acetic acid
  2. Oxygen
  3. Benzene
  4. Toluene

Answer: D [ Toluene ]

Description: Thermal diffusivity of toluene is 0.084 while that of acetic acid, oxygen, and benzene are 0.133, 0.206, and 0.081, respectively. Its unit is cm 2/s.


31) Which one is having the lowest value of diffusivity?

  1. Glucose
  2. Urea
  3. Ethanol
  4. Oxygen

Answer: A [ Glucose ]

Description: Thermal diffusivity of glucose is 0.60 while that of urea, oxygen, and ethanol are 8.06, 1.80, and 1.00, respectively. Its unit is cm2 /s.


32) Which one has the highest density?

  1. Snow
  2. Teflon
  3. Soil
  4. Sand

Answer: B [Teflon]

Description: Teflon, also known as polytetrafluoroethylene, has a density of 2200 kg/m3. It is a thermoplastic polymer, which is a white solid at room temperature. The density of snow, soil, and sand is 110 kg/m3, 2050 kg/m3, and 1515 kg/m3, respectively.


33) Which one has the least density?

  1. Ice
  2. Pyrex
  3. Paraffin
  4. Marble

Answer: A [ Ice ]

Description: Ice is water. Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaque bluish-white color.


34) What is the density of snow in kg/m3?

  1. 100
  2. 110
  3. 120
  4. 130

Answer: B [110]

Description: Snow is precipitation in the form of flakes of crystalline water ice that fall from clouds. It is a granular material with, soft, white, and fluffy structure.


35) What is the density of limestone in kg/m3?

  1. 2320
  2. 2430
  3. 2530
  4. 2630

Answer: A [2320]

Description: It is also known as calcium hydroxide. It is a colorless crystal that is obtained from calcium oxide.


36) What is the melting point of chromium?

  1. 2118 K
  2. 2218 K
  3. 2318 K
  4. 2418 K

Answer: A [ 2118 K ]

Description: It is a chemical element with an atomic number 24. It is a steely-gray, lustrous, hard, and brittle metal and has a high melting point.


37) Which one has the highest melting point?

  1. Bismuth
  2. Beryllium
  3. Cadmium
  4. Copper pure

Answer: B [ Beryllium ]

Description: The melting point of beryllium is 1550 k, while bismuth, cadmium, and pure copper are 545 K, 594 K, and 1358 K, respectively.


38) Which one has a maximum melting point?

  1. Palladium
  2. Magnesium
  3. Platinum pure
  4. Lead

Answer: C [ Platinum pure ]

Description: The melting point of pure platinum is 2045 K, while palladium, magnesium, and lead are 1827 K, 923 K, and 601 K, respectively.


39) Which one has a minimum melting point?

  1. Titanium
  2. Zinc
  3. Uranium
  4. Rhodium

Answer: B [ Zinc ]

Description: The melting point of zinc is 693 K, while titanium, uranium, and rhodium are 3269 K, 1406 K, and 2236 K, respectively.


40) The Concentration of the two phases in a closed system at the Interphase is

  1. Changes continuously
  2. Never changes
  3. Becomes zero
  4. Increases till the driving force becomes zero

Answer: B [ Never Changes ]

Description: The concentration changes only if the component of the two phases is added or removed. Generally, Interphase occurs at equilibrium. Once the additional component is added to a system at equilibrium, the concentration changes until it becomes uniform, but it will differ from the previous.


41) The equilibrium concentrations in the gas and the liquid phases, in mole fraction, give rise to a curve known as

  1. Equilibrium distribution curve
  2. Equilibrium concentration curve
  3. Differential distribution curve
  4. Differential concentration curve

Answer: A [ Equilibrium distribution curve ]

Description: The equilibrium distribution curve represents the phase-phase equilibrium curve with the coordinates of mole fractions in both phases.


42) In a certain process, there is a variation in the driving force between the phases. Such a process is

  1. Batch process
  2. Semi-batch process
  3. Continuous process
  4. Isothermal process

Answer: A [ Batch process ]

Description: In a batch process, concentration changes with time results in varying driving forces.


43) Assume an ideal solution with pure component A, has a vapor pressure of 300 mmHg and a total pressure of 1atm. The concentration in terms of mole ratio is

  1. 0.65
  2. 0.28
  3. 0.39
  4. None of the mentioned

Answer: A [ 0.65 ]

Description: According to Rauolt's law, for an ideal solution

Total pressure= concentration x vapour pressure

Concentration in mole fraction=300/760 =0.39

Concentration in mole ratio = 0.39/(1-0.39)=0.65.


44) The driving force line between the operating line and the equilibrium line depends on

  1. Relative diffusion resistance
  2. Relative mass resistance
  3. Cumulative resistance
  4. None of the mentioned

Answer: A [Relative diffusion resistance]

Description: As the driving force changes continuously at every point in a counter-current process, the relative diffusion resistance is considered.


45) A device where two insoluble phases are brought into contact is known as

  1. Trays
  2. Stage
  3. Cascade
  4. Sieves

Answer: B [Stage]

Description: The stage is a single device where the phases are allowed to contact each other.


46) During gas dispersion, if a chemical reaction between the gas and liquid phase is needed, then the preferred equipment is

  1. Agitated vessel
  2. Sparged vessel
  3. Tray tower
  4. Wetted wall column

Answer: A [Agitated vessel]

Description: For a reaction to occur, we need agitation for a perfect mixing between two phases.


47) In a Bubble column, if the velocity of the gas is low, then the bubble diameter equals to______

  1. Vessel
  2. Sparger orifice
  3. The volume of vessel/ interfacial area
  4. None of the mentioned

Answer: B [Sparger orifice]

Description: In sparged vessel or bubble column, the gas is dispersed into liquid through the orifice. So for a low gas velocity, the bubble's diameter will be similar to the orifice diameter.


48) The higher difference in pressure inside the tray tower cause

  1. Flooding
  2. Loading
  3. Weeping
  4. Dumping

Answer: A [Flooding]

Description: If more pressure drops, the liquid won't flow down to the adjacent trays. The liquid gets accumulated in one tray itself.


49) In an operation, the enthalpy is similar throughout the initial and final conditions. Such operation is

  1. Adiabatic
  2. Non-adiabatic
  3. Isothermal
  4. Non-isothermal

Answer: A [Adiabatic]

Description: For an adiabatic condition, there won't be any heat addition or removal. So the enthalpy remains the same.


50) The equilibrium characteristics of the solubility of a gas in liquid helps to determine the

  1. Rate
  2. Concentration
  3. Time
  4. No existence of equilibrium characteristics

Answer: A [Rate]

Description: The equilibrium diagram helps determine the flux with the mass transfer coefficient and concentration gradient.


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