Category: Objective Questions

Bioprocess Engineering Multiple Choice Questions on “Cell Nutrients”.

1. The Macronutrients concentration needed is __________
A. Greater than 10^-2 M
B. Less than 10^-2 M
C. Greater than 10 ^-4 M
D. Less than 10^-4 M
Answer: C
Explanation: Macronutrients are needed in concentrations larger than 10^-4 M. Carbon, nitrogen, oxygen, hydrogen, sulfur, phosphorus, Mg²⁺, and K⁺ are major macronutrients.

2. Which of the following components is not a Micronutrient?
A. Zn²⁺
B. Ca²⁺
C. Na⁺
D. Mg²⁺
Answer: D
Explanation: Elements used in large quantities by the plant are termed macronutrients, which can be further defined as primary or secondary. The primary nutrients include nitrogen (N), phosphorus (P), and potassium (K). These elements contribute to plant nutrient content, function of plant enzymes and biochemical processes, and integrity of plant cells. Deficiency of these nutrients contributes to reduced plant growth, health, and yield; thus they are the three most important nutrients supplied by fertilizers. The secondary nutrients include calcium (Ca), magnesium (Mg), and sulfur (S).

3. Viruses contain lipids.
A. True
B. False
Answer: A
Explanation: Viruses with a lipoprotein sheath may contain 25% lipid. Composition as a dry weight % includes <1.

4. Facultative autotrophs can grow under heterotrophic condition.
A. True
B. False
Answer: A
Explanation: Facultative autotrophs normally grow under autotrophic conditions; however, they can grow under heterotrophic conditions in the absence of CO₂ and inorganic energy sources.

5. Which of the following can grow in absence of CO₂ or carbon sources?
A. Autotrophs
B. Mixotrophs
C. Chemoautotrophs
D. Facultative autotrophs
Answer: D
Explanation: Facultative autotrophs normally grow under autotrophic conditions; however, they can grow under heterotrophic conditions in the absence of CO₂ and inorganic energy sources.

6. Which of the following is the key element in the regulation of cell metabolism?
A. Hydrogen
B. Phosphorus
C. Oxygen
D. Nitrogen
Answer: B
Explanation: The main role of potassium is to provide the ionic environment for metabolic processes in the cytosol, and as such functions as a regulator of various processes including growth regulation. Plants require potassium ions (K⁺) for protein synthesis and for the opening and closing of stomata, which is regulated by proton pumps to make surrounding guard cells either turgid or flaccid. Phosphorus constitutes about 3% of cell dry weight and is present in nucleic acids and in the cell wall of some gram-positive bacteria such as teichoic acids. Phosphorus is a key element in the regulation of cell metabolism.

7. Which of the following ion is required by the ribosomes?
A. H⁺
B. Mg²⁺
C. Mn²⁺
D. Ca²⁺
Answer: B
Explanation: Magnesium, serves as a structural component and is involved as a cofactor in many enzymatic reactions. Magnesium is a component of the chlorophyll structure. Magnesium is required to maintain ribosome integrity. Ribosomes specifically require Mg²⁺ ions.

8. What do you mean by the term “Trace elements”?
A. Very small amount
B. Medium amount
C. High amount
D. Very high amount
Answer: A
Explanation: Trace elements are essential to microbial nutrition. Lack of essential trace elements increases the lag phase (the time from inoculation to active cell replication in batch culture) and may decrease the specific growth rate and the yield. A trace element is a chemical element whose concentration (or other measure of amount) is very low (a “trace amount”).

9. What is “EDTA”?
A. Magnesium calcium edentate
B. Nitrogen phosphorus edentate
C. Sodium calcium edentate
D. Magnesium phosphorus edentate
Answer: C
Explanation: A specific salt of EDTA, known as sodium calcium edetate, is used to bind metal ions in the practice of chelation therapy, e.g., for treating mercury and lead poisoning. It is used in a similar manner to remove excess iron from the body. EDTA is a chelating agent and a chelating agent is a substance whose molecules can form several bonds to a single metal ion. In other words, a chelating agent is a multidentate ligand.

10. Which of the following is not a defined media?
A. Glucose
B. Magnesium chloride
C. Calcium chloride
D. Phenyl acetic acid
Answer: D
Explanation: Defined media contain specific amounts of pure chemical compounds with known chemical compositions. A medium containing glucose, (NH₄)₂SO₄, KH₂PO₄, and MgCl₂ is a defined medium. Complex media contain natural compounds whose chemical composition is not exactly known. Complex medium used in penicillin fermentation includes Phenyl acetic acid by continuous feed in a concentration of about 0.5-0.8% of total (g/liter).

11. Which device is used to measure the amount of energy stored in foods?
A. Rheometer
B. Adiabatic calorimeter
C. Bomb calorimeter
D. Heat flow calorimeter
Answer: C
Explanation: Complex organic food molecules such as sugars, fats, and proteins are rich sources of energy for cells because much of the energy used to form these molecules is literally stored within the chemical bonds that hold them together. Scientists can measure the amount of energy stored in foods using a device called a bomb calorimeter. With this technique, food is placed inside the calorimeter and heated until it burns. The excess heat released by the reaction is directly proportional to the amount of energy contained in the food.

12. Complex carbohydrates which make up cell wall in plants are?
A. Lactose
B. Fructose
C. Cellulose
D. Sucrose
Answer: C
Explanation: Cellulose is a very important polysaccharide because it is the most abundant organic compound on earth. Cellulose is a major component of tough cell walls that surround plant cells, and is what makes plant stems, leaves, and branches so strong.

13. Micronutrient which is important in transport of sugar, synthesis of enzymes and cell division is?
A. Boron
B. Potassium
C. Calcium
D. Phosphorus
Answer: A
Explanation: Boron (B. is a micronutrient critical to the growth and health of all crops. It is a component of plant cell walls and reproductive structures. It is a mobile nutrient within the soil, meaning it is prone to movement within the soil. Because it is required in small amounts, it is important to deliver B as evenly as possible across the field. Boron plays a key role in a diverse range of plant functions including cell wall formation and stability, maintenance of structural and functional integrity of biological membranes, movement of sugar or energy into growing parts of plants, and pollination and seed set. Adequate B is also required for effective nitrogen fixation and nodulation in legume crops.

14. The minerals involved in water-splitting reaction during photosynthesis are ___________
A. Manganese and chloride
B. Magnesium and sulfur
C. Magnesium and potassium
D. Magnesium and phosphorus
Answer: A
Explanation: Water splitting is catalyzed by the oxygen-evolving complex (OEC. of protein complex photosystem II (PSII), producing dioxygen gas, protons and electrons. O (2) is released into the atmosphere, sustaining all aerobic life on earth; product protons are released into the thylakoid lumen, augmenting a proton concentration gradient across the membrane; and photo-energized electrons pass to the rest of the electron-transfer pathway. The OEC contains four manganese ions, one calcium ion and (almost certainly) a chloride ion.

15. Energy is measured in ________
A. Micronutrient
B. Macronutrient
C. Calories
D. Kilogram
Answer: C
Explanation: A calorie is a unit that is used to measure energy. The Calorie you see on a food package is actually a kilocalorie, or 1,000 calories. A Calorie (kcal) is the amount of energy needed to raise the temperature of 1 kilogram of water 1 degree Celsius.

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Bioprocess Engineering Multiple Choice Questions on “Bioreactor Considerations”.

1. In tissue culture media which ions inhibit trypsin from the following?
A. Na⁺
B. Pb²⁺
C. Mg²⁺
D. Fe²⁺
Answer: C
Explanation: Tissue culture media contains calcium and magnesium ions, fetal bovine serum contains proteins that are trypsin inhibitors. Both Mg²⁺ and Ca²⁺ inhibit trypsin. To weaken the function of adhesion molecules.

2. EDTA function as_________
A. Divalent cations chelator
B. Divalent anion chelator
C. Monovalent cation chelator
D. Monovalent anion chelator
Answer: A
Explanation: EDTA is frequently included in the trypsin solution for its function as divalent cations chelator.

3. EDTA is carcinogenic.
A. True
B. False
Answer: B
Explanation: The typical concentration of use of EDTA is less than 2%, with the other salts in current use at even lower concentrations. The lowest dose reported to cause a toxic effect in animals was 750 mg/kg/day. These chelating agents are cytotoxic and weakly genotoxic, but not carcinogenic.

4. Spinner flask contains:
A. Spindle shaped agitators
B. Cylindrical agitators
C. Simple agitators
D. Spoon-like agitators
Answer: D
Explanation: Spinner flasks contain a magnetically driven impeller or spoonlike agitators that operate at 10 to 60 rpm. Aeration is usually by surface aeration using 5% CO₂-enriched and filtered air for mammalian cell lines. Spinner flasks are set on a magnetic stirrer plate in a CO₂ incubator.

5. What do you mean by microcarrier?
A. Carrier of small molecules
B. Carrier of small cells
C. Support material of suspended cells
D. Support material of adherent cells
Answer: D
Explanation: A microcarrier is a support matrix allowing for the growth of adherent cells in bioreactors. Microcarriers are regularly used to grow protein-producing or virus-generating adherent cell populations in the large-scale commercial production of biologics (proteins) and vaccines.

6. Membrane bioreactor is the combination of microfiltration and ultrafiltration.
A. True
B. False
Answer: A
Explanation: Membrane bioreactor (MBR) is the combination of a membrane process like microfiltration or ultrafiltration with a biological wastewater treatment process, the activated sludge process. It is now widely used for municipal and industrial wastewater treatment.

7. In microencapsulation which of the coating materials is not used for coating:
A. Sodium alginate
B. Sodium chloride
C. Gelatin
D. Polyvinyl alcohol
Answer: B
Explanation: The coating materials generally used for coating are:
▪ Ethyl cellulose
▪ Polyvinyl alcohol
▪ Gelatin
▪ Sodium alginate
The definition has been expanded, and includes most foods, where the encapsulation of flavors is the most common. The technique of microencapsulation depends on the physical and chemical properties of the material to be encapsulated.

8. What do you mean by spent medium?
A. Medium with high nutritional content
B. Hydrated
C. Dehydrated
D. Non-toxic
Answer: C
Explanation: After each sub-culture, the medium is discarded because it has been depleted of nutrients, dehydrated or accumulated toxic metabolic products.

9. In relation to surface area roller bottles are less advantageous than T-Flask.
A. True
B. False
Answer: B
Explanation: The roller-bottle system has an advantage over T-flasks because of increased surface area, agitation of the liquid, and better aeration. Roller bottles are not typically used for large-scale production because of high labor requirements and bottle-to-bottle variability.

10. DEAE beads are negatively charged.
A. True
B. False
Answer: B
Explanation: Anion-exchange chromatography is a process that separates substances based on their charges using an ion-exchange resin containing positively charged groups, such as diethyl-aminoethyl groups (DEAE). In solution, the resin is coated with positively charged counter-ions (cations).

11. Hydrofoils give low turbulence.
A. True
B. False
Answer: A
Explanation: Propellers (marine or hydrofoil) give an inlet and outlet which are on axial direction, preferably downward, they are characterized by a nice pumping flow, low energy consumption and low shear magnitude as well as low turbulence.

12. The cells are prone to damage at which region?
A. Inside the gas bubble
B. Outside the medium
C. Interface of a gas bubble and medium
D. Inside the medium
Answer: C
Explanation: Only cells that are at the interface of an eddy and another eddy or another surface (e.g., reactor wall) are likely to experience damage. Cells at the gas–liquid interface are particularly prone to damage. The breakage of air bubbles is particularly destructive to cells that accumulate at the interface of a gas bubble and medium.

13. Pluronic F-68 is____________
A. Ionic
B. Non-ionic
C. Covalent
D. Metallic
Answer: B
Explanation: Poloxamers are nonionic triblock copolymers composed of a central hydrophobic chain of polyoxypropylene (poly(propylene oxide)) flanked by two hydrophilic chains of polyoxyethylene (poly(ethylene oxide)). Poloxamers are also known by the trade names Synperonics, Pluronics, and Kolliphor.

14. The accumulation of toxic metabolic products in beads is a problem of which of the following methods?
A. Gel beads
B. Microencapsulation
C. Tubular ceramic matrix
D. Roller bottles
Answer: A
Explanation: High cell densities make high volumetric productivities possible. However, the control of microenvironmental conditions inside bead particles and the accumulation of toxic metabolic products in beads are potential problems in the immobilization of mammalian cells in gel beads (agar, alginate, collagen, polyacrylamide).

15. Small bubbles are more shear sensitive than large bubbles.
A. True
B. False
Answer: B
Explanation: Animal cells are very shear sensitive, and rising air bubbles may cause shear damage to cells, particularly at the point of bubble rupture. Very small bubbles are less damaging.

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Chemical Reaction Engineering Multiple Choice Questions & Answers on “Liquid and Gas Phase Reactions”.

1. Which of the following is true for gas phase reactions?
A. Increase in moles of product increases the volume of the reaction mixture
B. Increase in moles of product decreases the volume of the reaction mixture
C. Decrease in moles of product increases the volume of the reaction mixture
D. Increase in moles of product does not affect the volume of the reaction mixture
Answer: A
Explanation: Increase in moles of product increases reaction mixture volume. For a reaction proceeding such that the moles of products are higher than moles of reactants, volume of reaction mixture increases.

2. For an ideal gas at any given temperature and pressure, the ideal gas law is used to express ____
A. Concentration of gas molecules
B. Mobility of gas molecules
C. Kinetic energy of gas molecules
D. Potential energy of gas molecules
Answer: A
Explanation: Ideal gas law is given as, PV = nRT,
Where, P – Pressure
T – Temperature
R – Universal gas constant
n – Number of gas moles
V – Volume
Concentration is the number of moles per unit volume = (frac{n}{V} = frac{P}{RT}. )

3. The progress of which among the following reactions results in an increase in volume?
A. A → B
B. 3A → B
C. A → 4B
D. 2A → B
Answer: C
Explanation: Increase in moles of product is depicted by the reaction, A → 4B. The number of moles of product is higher than that of reactant.

4. The rate of a gas phase reaction involving the conversion of reactant ‘i’ to product is expressed as ____
A. (-r_i)=-(frac{1}{V^2}frac{dN_i}{dt} )
B. (-r_i)=-(frac{1}{V}frac{dN_i}{dt} )
C. (-r_i)=-(frac{dN_i}{dt} )
D. (-r_i)=-V(frac{dN_i}{dt} )
Answer: B
Explanation: The rate of change of the gaseous component ‘i’ in due course of the reaction is the change in number of moles of ‘i’ per unit time per unit volume of the reaction mixture. Hence, (-r_i)=-(frac{1}{V}frac{dN_i}{dt}. )

5. State true or false.
For a gas phase reaction, the rate of the reaction, (-r_A)=-(frac{1}{V}frac{dN_A}{dt}=-frac{dC_A}{dt}) is valid only if A → B.
A. True
B. False
Answer: A
Explanation: The volume of reaction mixture remains constant as the number of moles of reactant and product is the same. Hence, the number of moles per unit volume does not vary during the progress of the reaction. Hence, the number of moles per unit volume is expressed as concentration of the reactant, A.

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Chemical Reaction Engineering Question Paper focuses on “Stoichiometry – Batch Reactors with Variable Volume”.

1. State true or false.
A variable volume reactor is the one in which the reaction proceeds by a change in number of moles at a given pressure and temperature.
A. True
B. False
View Answer

Answer: A
Explanation: The pressure is held constant as the volume varies. The variable volume systems are also termed as constant pressure systems.

2. The fractional change in volume of a system for variable volume systems, expressed in terms of the number of moles is ____
A. ε = (frac{Change , in , number , of , moles , of , the , reaction , system , when , the , reaction , is , complete}{Total , number , of , moles , fed} )
B. ε = (frac{Total , number , of , moles , fed}{Change , in , number , of , moles , of , the , reaction , system , when , the , reaction , is , complete} )
C. ε = (frac{Number , of , moles , left , when , the , reaction , is , complete}{Total , number , of , moles , fed} )
D. ε = (frac{Total , number , of , moles , fed}{Number , of , moles , left , when , the , reaction , is , complete} )
View Answer

Answer: A
Explanation: ε is the fractional change in volume of the reaction system between no conversion and complete conversion of the reactant. It is the ratio of the change in moles of the reaction mixture to achieve complete conversion to the number of moles fed initially.

3. For the reaction A → 4R, the value of ε_A is ____
A. -3
B. 3
C. 4
D. 2
View Answer

Answer: B
Explanation: ε_A = (frac{V_{X_{A=1}} – V_{X_{A=0}}}{V_{X_{A=0}}} )
ε_A = (frac{4 – 1}{1}) = 3.

4. Final concentration of the reactant A in terms of conversion, for a variable volume batch reactor is ____
A. C_A = (frac{C_{A0}(1+ X_A.}{(1+ ε_A X_A.} )
B. C_A = (frac{C_{A0}(1 – X_A.}{(1- ε_A X_A.} )
C. C_A = (frac{C_{A0}(1 – X_A.}{(1+ ε_A X_A.} )
D. C_A = (frac{C_{A0}(1 – X_A.}{(ε_A X_A.} )
View Answer

Answer: C
Explanation: C_A = C_A0 (1 – X_A), for a constant volume reactor. The initial number of moles for a variable volume reactor, N_A = N_A0(1 – X_A). Volume, V = V₀(1 + ε_A X_A). C_A = (frac{N_A}{V}) = (frac{C_{A0}(1 – X_A.}{(1+ ε_A X_A.}.)

5. For the reaction A → 2R containing 50% moles initially, the value of ε_A is ____
A. 1
B. 0.75
C. 0.5
D. 0.9
View Answer

Answer: C
Explanation: Initially, there are 50 moles of inerts and 50 moles of A, 100 moles in total. On complete conversion, A forms (50×2) 100 moles of product, R. 1 mole reactant forms 2 moles of product. As the inerts do not get converted during the reaction, there are 150 moles in total at the end of the reaction. Hence, ε_A = (frac{150-100}{100}) = 0.5

6. The relationship between conversion and concentration for isothermal varying volume systems is ____
A. X_A = (frac{{1-frac{C_A}{C_{A0}}}}{1+(ε_A frac{C_A}{C_{A0}})} )
B. X_A = (frac{{1-frac{C_A}{C_{A0}}}}{1-(ε_A frac{C_A}{C_{A0}})} )
C. X_A = (frac{{1+frac{C_A}{C_{A0}}}}{1+(ε_A frac{C_A}{C_{A0}})} )
D. X_A = (frac{{1+frac{C_A}{C_{A0}}}}{1-(ε_A frac{C_A}{C_{A0}})} )
View Answer

Answer: A
Explanation: (frac{C_A}{C_{A0}} = frac{(1 – X_A.}{(1+ ε_A X_A.} )
X_A = 1 – (frac{C_A}{C_{A0}}). X_A = (frac{{1-frac{C_A}{C_{A0}}}}{1+(ε_A frac{C_A}{C_{A0}})}. )

7. The relation between rate and time for a zero order reaction in a variable volume reactor is expressed as ____
A. (frac{C_{A0}}{ε_A}ln(frac{V}{V_0})) = t
B. (frac{1}{ε_A} ln(frac{V}{V_0})) = kt
C. (frac{C_{A0}}{ε_A} ln(frac{V}{V_0})) = kt
D. (frac{C_{A0}}{ε_A} ln(frac{V}{CC_A})) = kt
View Answer

Answer: C
Explanation: For a zero order reaction in a variable volume reactor, -r_A = (frac{C_{A0}}{ε_A}ln(frac{d( lnV)}{dt})) = k. Hence, (frac{C_{A0}}{ε_A} ln(frac{V}{V_0})) = kt.

8. State true or false.
For negative values of ε_A, there is a reduction in volume of the reaction mixture as the reaction proceeds.
A. True
B. False
View Answer

Answer: A
Explanation: Negative value of ε_A implies that the initial volume is greater than the volume at complete conversion. The number of moles of the reactant is greater than the number of moles of product.

Chemical Reaction Engineering Multiple Choice Questions & Answers on “Tanks in Series Model”.

1. If τ is the average residence time and σ² is the standard deviation, then the number of tanks necessary to model a real reactor as N ideal tanks in series is ____
A. N = (frac{tau^2}{σ^2} )
B. N = (frac{σ^2}{τ^2} )
C. N = σ²
D. N = (frac{1}{τ^2} )
Answer: A
Explanation: τ² = 1 and σ² = (frac{1}{N}.) The standard deviation is obtained as, σ² = (int_0^∞)(t-τ)²E(t)dt.

2. State true or false.
The tank in series model is a single parameter model.
A. False
B. True
Answer: B
Explanation: The tank in series model is used to represent non – ideal flow in PFR. It is a one parameter model and the parameter is the number of tanks.

3. State true or false.
The tank in series model depicts a non – ideal tubular reactor as a series of equal sized CSTRs.
A. True
B. False
Answer: A
Explanation: A number of tanks in series represent a PFR. Any CSTR behaves like a PFR if its volume is reduced. Infinite CSTRs are connected in series to approach PFR behaviour.

4. For a first order reaction, where k is the first order rate constant, the conversion for N tanks in series is obtained as ____
A. X_A = 1-(frac{1}{(1+frac{τk}{N})^N} )
B. X_A = 1+(frac{1}{(1+frac{τk}{N})^N} )
C. X_A = (frac{1}{(1+frac{τk}{N})^N} )
D. X_A = (frac{1}{(1+frac{τk}{N})^N} )– 1
Answer: A
Explanation: For N tanks in series, the combination approaches non – ideal PFR behaviour. The concentration in the N^th CSTR is given as C_N = (frac{C_0}{(1+ τk)^N}.frac{C_N}{C_0} = frac{1}{(1+ τk)^N}.) X_A = 1 – (frac{C_N}{C_0}.) For N – tanks, X_A = 1-(frac{1}{(1+frac{τk}{N})^N}. )

5. Which of the following correctly represents the Damkohler number for a first order reaction? (Where, τ is the space time)
A. k
B. τ
C. (frac{1}{kτ})
D. k τ
Answer: D
Explanation: Damkohler number is the product of first order rate constant and space time. It is the measure of the degree of completion of reaction.

6. According to tanks in series model, the spread of the tracer curve is proportional to ____
A. Square of distance from the tracer origin
B. Square root of distance from the tracer origin
C. Cube of distance from the tracer origin
D. Inverse square of distance from the tracer origin
Answer: B
Explanation: (σ_{tracer , curve}^2) α Distance from point of origin
Spread of the curve α (sqrt{Distance , from , origin}. )

7. If τ² = 100 and σ² = 10, the number of tanks necessary to model a real reactor as N ideal tanks in series is ____
A. 1
B. 10
C. 5
D. 100
Answer: B
Explanation: N = (frac{τ^2}{σ^2} )
N = (frac{100}{10}) = 10.

8. If τ = 5 s, first order rate constant, k = 0.25 sec^-1 and the number of tanks, N is 5, then the conversion is ____
A. 67.2%
B. 75%
C. 33%
D. 87.45%
Answer: A
Explanation: X_A = 1-(frac{1}{(1+frac{τk}{N})^N} )
1-(frac{1}{(1+frac{5×0.25}{5})^5}) = 67.2%.

9. The exit age distribution as a function of time is ____
A. E = (frac{t^{N-1}}{τ^N}frac{N^N}{(N-1)!}e^frac{-tN}{τ})
B. E = (frac{t^{N-1}}{τ^N}frac{N}{(N-1)!}e^frac{-tN}{τ})
C. E = (frac{t^N}{τ^N}frac{N^N}{(N-1)!}e^frac{-tN}{τ})
D. E = (frac{t^{N-1}}{τ^2}frac{N^N}{(N-1)!}e^frac{-tN}{τ})
Answer: A
Explanation: For N tanks in series, the exit age distribution is, E = (frac{t^{N-1}}{τ^N}frac{N^N}{(N-1)!}e^frac{-tN}{τ}.) The number of tanks in series, N = (frac{τ^2}{σ^2}. )

10. There are 5 tanks connected in series. If the average residence time is 5 sec, first order rate constant is 0.5 sec^-1, the initial concentration is 5(frac{mol}{m^3},) then the conversion at the exit of 5^th reactor in ((frac{mol}{m^3})) is ____
A. 0.34
B. 0.51
C. 0.65
D. 0.81
Answer: C
Explanation: C_N = C₀ (frac{1}{(1+frac{τk}{N})^N} )
C_N = 5×(frac{1}{(1+frac{5×0.5}{5})^5} )
C_N = 0.65(frac{mol}{m^3}. )

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