250+ TOP MCQs on Heuristic Algorithms and Answers

Bioinformatics Multiple Choice Questions on “Heuristic Algorithms”.

1. Which of the following is untrue regarding the Progressive Alignment Method?
A. Progressive alignment depends on the stepwise assembly of multiple alignments and is heuristic in nature
B. It speeds up the alignment of multiple sequences through a multistep process
C. It first conducts pair wise alignments for each possible pair of sequences using the Needleman–Wunsch global alignment method and records these similarity scores from the pair wise comparisons
D. Its drawback is it slows down the alignment of multiple sequences through a single step process

Answer: D
Explanation: Progressive alignment speeds up the alignment of multiple sequences through a multistep process further, the scores can either be percent identity or similarity scores based on a particular substitution matrix. Both scores correlate with the evolutionary distances between sequences.

2. Clustal is a progressive multiple alignment program available either as a stand-alone or on-line program.
A. True
B. False

Answer: A
Explanation: Probably the most well-known progressive alignment program is Clustal. The stand-alone program, which runs on UNIX and Macintosh, has two variants, Clustal W and Clustal X. The W version provides a simple text-based interface and the X version provides a more user-friendly graphical interface.

3. Which of the following is untrue regarding the progressive alignment method?
A. The program also applies a weighting scheme to increase the reliability of aligning divergent sequences (sequences with less than 25% identity)
B. The progress is done by down weighting redundant and closely related groups of sequences in the alignment by a certain factor
C. This scheme is useful in enhancing similar sequences from dominating the alignment
D. This scheme is useful in enhancing similar sequences from dominating the alignment

Answer: c
Explanation: This scheme is useful in enhancing similar sequences from dominating the alignment. Further, the weight factor for each sequence is determined by its branch length on the guide tree. The branch lengths are normalized by how many times sequences share a basal branch from the root of the tree.

4. Which of the following is not a drawback of the progressive alignment method?
A. The progressive alignment method is not suitable for comparing sequences of different lengths because it is a global alignment–based method
B. In this method the use of affine gap penalties, long gaps are not allowed, and, in some cases, this may limit the accuracy of the method
C. In this method the use of affine gap penalties, long gaps is allowed, and, in some cases, this may limit the accuracy of the method
D. The final alignment result is also influenced by the order of sequence addition

Answer: c
Explanation: Another major limitation is the “greedy” nature of the algorithm: it depends on initial pair wise alignment. Once gaps introduced in the early steps of alignment, they are fixed. The final alignment could be far from optimal. The problem can be more glaring when dealing with divergent sequences.

5. Which of the following is untrue regarding T-Coffee?
A. It stands for Tree-based Consistency Objective Function for alignment Evaluation
B. It performs progressive sequence alignments as in Clustal.
C. The global pair wise alignment is not performed using the Clustal program.
D. The local pair wise alignment is generated by the Lalign program, from which the top ten scored alignments are selected

: c
Explanation: The global pair wise alignment is performed using the Clustal program. The main difference is that, in processing a query, T-Coffee performs both global and local pair wise alignment for all possible pairs involved. The collection of local and global sequence alignments is pooled to form a library. The consistency of the alignments is evaluated.

6. Which of the following is untrue about iterative approach?
A. The iterative approach is based on the idea that an optimal solution can be found by repeatedly modifying existing suboptimal solutions
B. Because the order of the sequences used for alignment is different in each iteration
C. This method is also heuristic in nature and does not have guarantees for finding the optimal alignment
D. This method is not based on heuristic methods

Answer: D
Explanation: This method is based on heuristic methods. The procedure starts by producing a low-quality alignment and gradually improves it by iterative realignment through well-defined procedures until no more improvements in the alignment scores can be achieved.

7. Which of the following is untrue about PRRN?
A. PRRN is a web-based program that uses a double nested iterative strategy for multiple alignment
B. It performs multiple alignments through two sets of iterations: inner iteration and outer iteration
C. In the outer iteration, an initial random alignment is generated that is used to derive a UPGMA tree
D. In the inner iteration, the sequences are randomly divided into multiple groups

Answer: D
Explanation: In the inner iteration, the sequences are randomly divided into two groups. Randomized alignment is used for each group in the initial cycle, after which the alignment positions in each group are fixed. The two groups, each treated as a single sequence, are then aligned to each other using global dynamic programming. The process is repeated through many cycles until the total SP score no longer increases. At this point, the resulting alignment is used to construct a new UPGMA tree.

8. The major drawback of the progressive and iterative alignment strategies is that they are largely global alignment based and may therefore fail to recognize conserved domains and motifs among highly divergent sequences of varying lengths.
A. True
B. False

Answer: A
Explanation: For such divergent sequences that share only regional similarities, a local alignment based approach has to be used. The strategy identifies a block of ungapped alignment shared by all the sequences, hence, the block-based local alignment strategy.

9. Which of the following is untrue about DIALIGN2?
A. It is a web based program designed to detect local similarities
B. It is designed to detect global similarities
C. It does not apply gap penalties and thus is not sensitive to long gaps
D. The method breaks each of the sequences down to smaller segments and performs all possible pair wise alignments between the segments

Answer: B
Explanation: High-scoring segments, called blocks, among different sequences are then compiled in a progressive manner to assemble a full multiple alignment. It places emphasis on block-to-block comparison rather than residue-to-residue comparison. The sequence regions between the blocks are left unaligned. The program has been shown to be especially suitable for aligning divergent sequences with only local similarity.

10. Match-Box compares segments of some of the nine residues of possible Pair wise alignments.
A. True
B. False

Answer: b
Explanation: Match-Box compares segments of every nine residues of all possible pair wise alignments. It is a web-based server that also aims to identify conserved blocks (or boxes) among sequences. The program compares segments of every nine residues of all possible pair wise alignments. If the similarity of particular segments is above a certain threshold across all sequences, they are used as an anchor to assemble multiple alignments; residues between blocks are unaligned.

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300+ TOP MCQs on YAC and Expression Systems and Answers

Genetic Engineering Multiple Choice Questions on “YAC and Expression Systems”.

1. When YAC is used to clone DNA. What is the size of the DNA that can be cloned?
a) Large (upto megabases)
b) Small (upto few hundred bases)
c) No size restriction
d) Medium (upto kilobases)
Answer: a
Explanation: YACs are sophisticated cloning vectors that are used for propagating large stretches of DNA which are upto a few megabases.

2. TEL is the ______ sequence derived from the ends of ribosomal RNA-encoding molecules from the macromolecules of the protozoan Tetrahyena.
a) centromeric
b) telomeric
c) can be either centromeric or telomeric
d) can be present anywhere on the chromosome
Answer: b
Explanation: TEL is the telomeric sequence derived from the ends of ribosomal RNA-encoding molecules from the macromolecules of the protozoan Tetrahyena. It is a part of YAC.

3. Choose the incorrect statement for YAC vectors.
a) The YAC molecule is approximately 10 kb in size
b) It contains both yeast origin of replication and prokaryotic origin of replication
c) It doesn’t contain ampicillin resistant gene
d) It contains TEL sequence
Answer: c
Explanation: YAC vectors are approximately 10kb in size. It contains both yeast origin of replication and prokaryotic origin of replication. It also contains TEL sequence and an ampicillin resistant gene.

4. If YAC DNA is digested with BamHI and ECoRI, how many fragments are generated?
a) 1
b) 2
c) 3
d) 4
Answer: c
Explanation: If YAC DNA is digested with BamHI and ECoRI, three fragments are generated. Two fragments are having TEL sequence and one is lacking this sequence.

5. Transformed cells in the case of YAC can be selected by the presence of both URA3 and TRP1 genes.
a) True
b) False
Answer: a
Explanation: Transformed cells in the case of YAC can be selected by the presence of both URA3 and TRP1 genes. The presence of both these indicates that both the arms of YAC are acquired.

6. GAL1 is a controllable promoter and is obtained from genes for galactose metabolism. It is known for encoding ______
a) UDP-galactose-4-empirase
b) Galactokinase
c) Both UDP-galactose-4-empirase and galactokinase
d) Glucokinase
Answer: b
Explanation: GAL1 is a controllable promoter and is obtained from genes for galactose metabolism. It encodes for galactokinase and GAL10 encodes for UDP-galactose-4-empirase.

7. Transcription of GAL1 and GAL10 is suppressed in the presence of _______
a) glucose
b) galactose
c) maltose
d) fructose
Answer: a
Explanation: Transcription of GAL1 and GAL10 is suppressed in the presence of glucose and elevated in the presence of galactose.

8. How many deletion variations of GAL1 promoter are there?
a) 1
b) 2
c) 3
d) 4
Answer: b
Explanation: In GAL1 promoter, there are 2 deletion variations present. These deletion variations are known as GALL and GALS.

9. Promoters such as GAL1 can be used to direct synthesis of either unmodified or fusion proteins.
a) True
b) False
Answer: a
Explanation: Promoters such as GAL1 can be used to direct synthesis of either unmodified or fusion proteins. The fusion proteins can incorporate products of GAL1 or other sequences such as lacZ.

10. Which of the following are advantageous to be used for expression of eukaryotic cells?
a) Prokaryotic systems
b) Yeast cells
c) Fungi cells
d) Algae cells
Answer: b
Explanation: It is advantageous to use yeast cells for expression of eukaryotic cells in place of prokaryotic cells. It is so because in yeast cells post-translational modifications can be done but these modifications are not possible in prokaryotic cells.

300+ TOP MCQs on Modifications in PCR – 1 and Answers

Genetic Engineering Multiple Choice Questions on “Modifications in PCR – 1”.

1. What are the possibilities which can occur until the temperature has reached for primer annealing?
a) Extension doesn’t starts until the appropriate temperature is reached
b) Extension may start even when the temperature is low
c) At low temperature, there is specific annealing of primer taking place
d) There are more specific products which are generated
Answer: b
Explanation: Until the temperature has reached for primer annealing there are chances of extension by polymerase. It is so because at low temperatures primer can anneal in a non specific manner and thus non specific products are generated.

2. Hot-start PCR is a modification of PCR. Which of the following is not corresponding to it?
a) The basis is that extension is not started until the first cycle reaches its maximum temperature
b) The polymerase is added after the first cycle has reached its maximum temperature or melting temperature
c) It is satisfactory for small number of samples
d) It leads to generation of non specific products
Answer: d
Explanation: Hot-start PCR is a modification which is used in order to overcome the problem of the extension before the maximum temperature of first cycle is reached. Hence, polymerase is added only after the maximum temperature for first cycle is reached. Hence, there are more specific products which are generated because proper annealing of primers has taken place. It is suitable for a small number of samples but not for a large number of samples.

3. An alternative to adding polymerase at later stage is __________
a) Make the polymerase inactive by binding it to an antibody
b) Introduce the polymerase or Magnesium in clay beads
c) Make the polymerase inactive by attaching groups which cause stearic inhindrance
d) Introduction of polymerase or Magnesium in plastic wires
Answer: a
Explanation: An alternative to start the extension at higher temperature is to make the polymerase inactive by binding an antibody to it. The antibody detaches itself at a higher temperature and thus polymerase is activated at higher temperature. Also, the polymerase or Magnesium can be introduced into wax beads and these beads melt at higher temperatures. Magnesium is required for the polymerase to function.

4. The primer annealing temperature is often very low from the maximum temperature. This low temperature leads to some mismatches.
a) True
b) False
Answer: a
Explanation: The primer annealing temperature is often very low from the maximum temperature. Though the low temperature is for stable binding of the template and the primer but at times it leads to mismatches.

5. Touch-down PCR is another modification. Its characteristics include:
a) Lowering the temperature for primer annealing
b) Primer annealing is done at higher temperatures initially
c) The temperature is abruptly reduced in the second cycle
d) In earlier cycles less stringent conditions are there and in later cycles, more stringent conditions are there
Answer: b
Explanation: It is done in order to overcome the slight mismatch which takes place at lower temperatures. For this, initially the temperature is kept very high and it is reduced in further cycles. As the temperature is reduced, a stage is reduced at which correct primer-template binding is possible but not the incorrect one. In this, in the earlier cycles more stringent conditions are there and in later cycles less stringent conditions are there.

6. If two successive PCR are carried out, it is called as __________
a) Touch-down PCR
b) Hot-start PCR
c) Combined PCR
d) Nested PCR
Answer: d
Explanation: Nested PCR is that in which two PCRs are carried out. In the first PCR, it uses a conventional template and the second PCR is carried out using the product of first PCR as a template.

7. If two successive PCRs are carried out, in which PCR there are chances of having a non-specific product?
a) First PCR
b) Second PCR
c) Both the PCRs
d) It depends on the annealing temperature
Answer: a
Explanation: If two successive PCRs are carried out, there are non-specific products created in the first PCR. But there are least chances that non-specific products also have annealing sites for both the primers in the second PCR. Hence, non specific products are not generated in the second PCR.

8. The process of inserting an amplified PCR product in a vector for cloning is known as __________
a) making library
b) insertion
c) making a hard copy
d) making a PCR based vector
Answer: c
Explanation: The process of inserting an amplified PCR product in a vector for cloning is termed as making a hard copy. It is further maintained by conventional means.

9. How can PCR product be cloned into a vector?
a) It can be done only when PCR products are blunt-ended
b) It can be done only by restriction enzyme digestion
c) Both the methods can be used
d) The blunt-ended approach is favoured
Answer: b
Explanation: PCR product can be cloned into a vector if the DNA molecules are blunt ended or it can also be done by restriction enzyme digestion. In restriction enzyme digestion restriction sites are introduced.

10. Which of the following statement is incorrect regarding the cloning of PCR products?
a) In cloning via restriction enzymes, restriction sites are induced before amplification is carried out
b) The restriction sites are induced in the primers before annealing
c) The intermediate molecules are having restriction sites at both ends
d) The amplified molecules can be cut at both the ends by appropriate enzymes
Answer: c
Explanation: If cloning is done via restriction enzymes, restriction sites are induced before amplification. The restriction sites are induced in the primers before annealing. As the primer binds, the restriction sites are induced at one end of the intermediate molecule. In full length molecules, restriction sites are at both ends. And the amplified molecules can be cut at both the ends by appropriate enzymes.

11. Topoisomerse I is also used for cloning of PCR product at times. Which of the statement holds true for such type of cloning?
a) The restriction site is induced into the vector and the topisomerase enzyme is induced into the PCR primers
b) The topoismerase I is used for cutting both the strands
c) The induction of topoisomerase enzyme is done into the vector in the case it is very small in size
d) The restriction site is induced into the PCR primers and the topoisomerase enzyme is induced into the vector
Answer: d
Explanation: In the case of this type of cloning, the restriction site is induced into the PCR primers and the enzyme is induced into the vector. The enzyme cuts the PCR product at the restriction site and joins it to the vector. Topoisomerase I is responsible for cutting only one strand and Topoisomerase II cuts both the strands.

12. Generally, amplification is carried out between the PCR primers. But if amplification is carried out outside the primers, it is called as __________
a) Inverse PCR
b) Circular PCR
c) Non-conventional PCR
d) In-situ PCR
Answer: a
Explanation: Generally, the amplification is carried out of the region which is flanked by the primers. But in inverse primers amplification is carried out of the region which lies outside the primers.

250+ TOP MCQs on Local Sequence Alignment and Answers

Bioinformatics Multiple Choice Questions on “Local Sequence Alignment”.

1. When did Smith–Waterman first describe the algorithm for local alignment?
A. 1950
B. 1970
C. 1981
D. 1925

Answer: c
Explanation: The algorithm was first proposed by Temple F. Smith and Michael S. Waterman in 1981. The Smith–Waterman algorithm performs local sequence alignment; that is, for determining similar regions between two strings of nucleic acid sequences or protein sequences.

2. Which of the following does not describe local alignment?
A. A local alignment aligns a substring of the query sequence to a substring of the target sequence
B. A local alignment is defined by maximizing the alignment score, so that deleting a column from either end would reduce the score, and adding further columns at either end would also reduce the score
C. Local alignments have terminal gaps
D. The substrings to be examined may be all of one or both sequences; if all of both are included then the local alignment is also global

Answer: c
Explanation: Local alignments never have terminal gaps, because a higher score could be obtained by deleting the gaps (which always have negative scores, i.e. penalties). In case of global alignment there are terminal gaps while analyzing.

3. Which of the following does not describe local alignment algorithm?
A. Score can be negative
B. Negative score is set to 0
C. First row and first column are set to 0 in initialization step
D. In traceback step, beginning is with the highest score, it ends when 0 is encountered

Answer: A
Explanation: Score can be negative. When any element has a score lower than zero, it means that the sequences up to this position have no similarities; this element will then be set to zero to eliminate influence from previous alignment. In this way, calculation can continue to find alignment in any position afterward.

4. Local alignments are more used when _____________
A. There are totally similar and equal length sequences
B. Dissimilar sequences are suspected to contain regions of similarity
C. Similar sequence motif with larger sequence context
D. Partially similar, different length and conserved region containing sequences

Answer: A
Explanation: The given description is suitable for global alignment. It attempts to align maximum of the entire sequence unlike local alignment where the partially similar sequences are analyzed.

5. Which of the following does not describe BLOSUM matrices?
A. It stands for BLOcks SUbstitution Matrix
B. It was developed by Henikoff and Henikoff
C. The year it was developed was 1992
D. These matrices are logarithmic identity values

Answer: D
Explanation: These matrices are actual percentage identity values. Or simply, they depend on similarity. Blosum 62 means there is 62 % similarity.

6. Which of the following is untrue regarding the gap penalty used in dynamic programming?
A. Gap penalty is subtracted for each gap that has been introduced
B. Gap penalty is added for each gap that has been introduced
C. The gap score defines a penalty given to alignment when we have insertion or deletion
D. Gap open and gap extension has been introduced when there are continuous gaps (five or more)

Answer: B
Explanation: Dynamic programming algorithms use gap penalties to maximize the biological meaning. The open penalty is always applied at the start of the gap, and then the other gaps following it is given with a gap extension penalty which will be less compared to the open penalty. Typical values are –12 for gap opening, and –4 for gap extension.

7. Among the following which one is not the approach to the local alignment?
A. Smith-Waterman algorithm
B. K-tuple method
C. Words method
D. Needleman-Wunsch algorithm

Answer: D
Explanation: Local alignment can be distinguished on two broad approaches, Smith-Waterman algorithm and word methods, also known as k-tuple methods and they are implemented in the well-known families of programs FASTA and BLAST.

8. Which of the following does not describe k-tuple methods?
A. k-tuple methods are best known for their implementation in the database search tools FASTA and the BLAST family
B. They are also known as words methods
C. They are basically heuristic methods to find local alignment
D. They are useful in small scale databases

Answer: D
Explanation: k-tuple or word methods are especially useful in large-scale database searches where a large proportion of stored sequences will have essentially no significant match with the query sequence. They are heuristic methods that are not guaranteed to find an optimal alignment solution but are significantly more efficient than Smith-Waterman algorithm.

9. Which of the following does not describe BLAST?
A. It stands for Basic Local Alignment Search Tool
B. It uses word matching like FASTA
C. It is one of the tools of the NCBI
D. Even if no words are similar, there is an alignment to be considered

Answer: D
Explanation: If no words are similar, there is no alignment i. e. it will not find matches for very short sequences. But it is considerably accurate as compared to other tools and hence is quite popular.

10. Which of the following is untrue regarding BLAST and FASTA?
A. FASTA is faster than BLAST
B. FASTA is the most accurate
C. BLAST has limited choices of databases
D. FASTA is more sensitive for DNA-DNA comparisons

Answer: A
Explanation: BLAST is faster than FASTA and most other tools. The speed and relatively good accuracy of BLAST is the key why the tool is the most popular bioinformatics search tool.

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250+ TOP MCQs on Data Analysis and Answers

Bioprocess Engineering Multiple Choice Questions on “Data Analysis”.

1. Which type of graph plot is used to analyze the effect of temperature on the rates of chemical reactions?
A. Dot plot
B. Normal probability plot
C. Arrhenius plot
D. Line weaver-Burk plot

Answer: C
Explanation: An Arrhenius plot displays the logarithm of kinetic constants (ln (k), ordinate axis) plotted against inverse temperature (1/T, abscissa). The Arrhenius equation can be written as:
ln (k) = ln (A. – (Ea/R) (1/T)
Where :
k = Rate constant
A = Pre-exponential factor
Ea = Activation energy
R = Gas constant
T = Absolute temperature, K
In the right, which represents the y-coordinate axis.

2. From the below representation of growth phase, which is the missing growth phase?

A. Exponential Growth Phase
B. Final Lag Phase
C. Initial Log Phase
D. Final Log phase

Answer: A
Explanation: The Log/ Exponential Growth phase is a period characterized by cell doubling. If growth is not limited, doubling will continue at a constant rate so both the number of cells and the rate of population increase doubles with each consecutive time period. For this type of exponential growth, plotting the natural logarithm of cell number against time produces a straight line.

3. If the substrate is given in molar concentration how would you define it’s Molarity and Molality based on the temperature condition?
A. Molarity and Molality both will change on effect of temperature
B. Molarity will change but not Molality
C. Molality will change but not Molarity
D. Normality of the reaction will change

Answer: B
Explanation: Molarity is the number of moles of solute per kilogram of the Solvent. That is because molarity does not depend on temperature, (neither on number of moles of solute nor mass of solvent will be affected by changes of temperature). While molarity changes as temperature changes because molarity is affected by temperature. This is because it is based on the volume of the solution, and the volume of a substance will be affected by changes in temperature.

4. What is the generation time of a bacterial population that increases from 10,000 cells to 10,000,000 cells in four hours of growth?

A. 24 minutes
B. 30 minutes
C. 34 minutes
D. 60 minutes

Answer: A

5. On which type of plot the best fit line is represented?
A. Dot plot
B. Line weaver- Burk plot
C. Scatter plot
D. Bland- Altman plot

Answer: C
Explanation: A line of best fit is a straight line drawn through the center of a group of data points plotted on a scatter plot. Scatter plots depict the results of gathering data on two variables. The line of best fit shows whether these two variables appear to be correlated and can be used to help identify trends occurring within the dataset. Analysts may use the line of best fit when determining a relationship between two variables where one variable is independent and one variable is being examined for dependency.

6. In the case of Rota meter, which is used for measuring the water flow rate?
A. Only one variable is involved, i.e. independent variable (the Rota meter reading)
B. Only two variables are involved: one independent variable(the Rota meter reading) and one dependent variable (the water flow rate)
C. Only two variables are involved: one independent variable(the water flow rate) and one dependent variable (the Rota meter reading)
D. Only one variable is involved, i.e. independent variable (the water flow rate)

Answer: B
Explanation: Rota meter is a device which measures flow rate. This is done by allowing the cross-sectional area the fluid travels through to vary, causing a measurable effect, i.e. water flow rate is dependent on Rota meter.

7. The diauxic growth curve mainly found in E.coli in the case of two types of nutrients is found in Batch culture is based on which equation?
A. Monod equation
B. Michaelis – Menten equation
C. Schrodinger equation
D. Lyapunov equation

Answer: A
Explanation: Jacques Monod discovered diauxic growth in 1941 during his experiments with Escherichia coli and Bacillus subtilis. While growing these bacteria on various combinations of sugars during his doctoral thesis research, Monod observed that often two distinct growth phases are clearly visible in batch culture.

8. Essentially in an experiment involving bacteria, we measure Optical density of the media where the bacteria grow at different time point from the same flask. If we have 2 or more types of bacteria and want to investigate whether the growth curve of those bacteria are significantly different, what do you think the best analysis can be applied for this purpose?
A. Linear regression analysis or general regression analysis
B. Non- linear regression analysis or general regression analysis
C. Logistic regression analysis
D. Stepwise regression analysis

Answer: B
Explanation: If the growth rates fit a polynomial curve, you can use General Regression and enter the bacteria type as categorical variable. Otherwise, you may need to use nonlinear regression separately for each type.

9. What is the basic Optical Density (O.D. of the bacterial cells?
A. 680nm
B. 600nm
C. 200nm
D. 280nm

Answer: B
Explanation: 600nm is a wavelength of light that is minimally absorbed by material within cells. Therefore, they can be more reliably used than other wavelengths (in most common situations). To simply, measure the scattering of light due to turbidity (just general presence of particles in a solution).

10. For what MANOVA is used for?
A. Detection of biological samples
B. Detection of the best fit curve
C. Comparison between monovariate samples
D. Comparison between multivariate samples

Answer: D

250+ TOP MCQs on Solving Unsteady – State Mass Balances and Answers

Bioprocess Engineering Multiple Choice Questions on “Solving Unsteady – State Mass Balances”.

1. A compound dissolves in water at a rate proportional to the product of the amount of undissolved solid and the difference between the concentration in a saturated solution and the actual solution; i.e., Csat – C(t). A saturated solution of this compound contains 40 g per 100 g of water. In a test run starting with 20 kg of undissolved compound in 100 kg of water, it was found that 5 kg dissolved in 3 hr. if the test continues, how many kg of compound will remain undissolved after 7 hr? Assume that the system is isothermal.
A. 11.56 kg
B. 10.72 kg
C. 11.76 kg
D. 10.52 kg

Answer: B

2. What is the first – order decay?
A. The rate of loss of the pollutant is constant
B. The rate of loss of the reactant is constant
C. The rate of loss of the pollutant is directly proportional to its concentration
D. The rate of loss of the reactant is directly proportional to its concentration

Answer: C
Explanation: First – order decay is the rate of loss of the pollutant is directly proportional to its concentration:
|dc/dt|reaction = -kC
For such a pollutant, mreaction = – V kC.

3. The water level in a municipal reservoir has been decreasing steadily during a dry spell, and there is a concern that the drought could continue for another 60 days. The local water company estimates that the consumption rate in the city is approximately 107 L/day. The state conservation service estimates that rainfall and stream drainage into the reservoir coupled with evaporation from the reservoir should yield a net water input rate of 106 exp (-t/100) L/day, where t is the time in days from the beginning of the drought, at which time the reservoir contained an estimated 109 liters of water.
Integrate the balance to calculate the reservoir volume at the end of the 60 days of continued drought.
A. 4.50 × 109 L
B. 4.50 × 108 L
C. 4.45 × 108 L
D. 4.45 × 109 L

Answer: C

4. Which one process is not a transient process?
A. Fed- batch
B. Batch
C. Continuous
D. Semi- batch

Answer: A
Explanation: Batch, semi-batch and continuous are transient as when they are start up, shut down or become transient at other times due to planned or unexpected changes in operating conditions.

5. Which of the following is the steady state condition based on the water tank concept?
A. Qin ≠ Qout
B. Qin = Qout
C. Qin > Qout
D. Qin < Qout

Answer: B
Explanation: Water flows in = Water flows out;
If Qin = Qout: Steady state (No accumulation)
No increase in level, mass, volume etc.
In time, there is no change in the system.

6. Determine the volume required for a PFR to obtain the degree of pollutant reduction, Assume that the flow rate and first-order decay rate constant are unchanged (Q = 50 m3/day, k = 0.216 day-1), Cout / Cin = 32/100 = 0.32.
A. 204 m3
B. 234 m3
C. 254 m3
D. 264 m3

Answer: D

7. In a batch process, the reaction takes place in the presence of an acid medium. The acid is drained from the reaction vessel at the rate of 15ml/s as a result of the density difference of the acid from the reacting component. To avoid wastage of acid, it is recycled to an acid tank which has 1000 L capacity. The acid drained from the reaction vessel, picks up 50 g/L solids from the reactor. Acid is fed once again to the process from acid tank. When the process is started, the acid is almost pure in the tank as a result of filtration. As the reaction proceeds, acid in the tank gets more and more contaminated with the solids. The concentration of the solids should not exceed 100 g/L from the process point of view. The batch time is 16h. Estimate whether the concentration of the solids will exceed 100g/L during the batch reaction.
A. 37.04 h
B. 30.05 h
C. 36.04 h
D. 32.05 h

Answer: A
Explanation: Input of the solids to the tank = 15 (c+50) t∆g/1000

Output of solids from tank = 15 Δt c / 1000g

Accumulation in the tank = 1000 (c+ΔC. – 1000c

= 1000Δc g
Input – output = Accumulation

1/1000 [15 (c+50) Δt – 15cΔt] = 1000Δt

750 Δt = 1000000 Δc

Converting into differential form ,

dt = 1333.33dc, when t=0 and c=0.

Integration therefore yields,

t = 1333.33c
C = 100g/L is the limit

t = 100 × 1333.33
= 133.33 s
= 37.04 h.

8. Which of the following is not an example of batch process?
A. Cooking
B. Specialty chemicals
C. Refining
D. Brewing

Answer: C
Explanation: Refining is a continuous process as feed and products flow continuously through process. System is open, and usually modeled as steady flow. Examples: Petroleum refining (except coking, blending).

9. Due to algal growth in a water supply reservoir in a neighborhood, the water has acquired an unpleasant taste. The compound is non-degradable, and the water utility has decided that the best way to deal with the situation is simply to flush the contaminant out of the system. The reservoir contains 11,000 m3 of water, and the proposal is to pump 300 m3/h of clean water through the system and discharge the effluent to the sewer system until 95% of the offending compound has been removed. If the reservoir is intensely mixed, how much flushing water will be required?
A. 30, 000 m3
B. 33, 000 m3
C. 35, 000 m3
D. 39, 000 m3

Answer: B

10.” A balloon is filled with air at a steady rate.” Which process can be correct for this condition?
A. Semi – batch
B. Batch
C. Fed – batch
D. Continuous

Answer: A