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Biotechnology Multiple Choice Questions1) The restriction endonuclease has a defense mechanism in the bacterial system against foreign DNA such as viruses. But how can it protect its DNA?
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?
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?
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 __________
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?
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:
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?
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 ___________
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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
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
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
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
Answer: A [ 28.84 ] Description: (0.21) (32) + (0.79) (28) = 28.84. 25) What is the value of emissivity for polished aluminum?
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?
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?
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 __________
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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
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
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
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
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
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
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
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______
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
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
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
Answer: A [Rate] Description: The equilibrium diagram helps determine the flux with the mass transfer coefficient and concentration gradient.
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