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The CORRECT choice is (a) Containing single TYPE of organism

Best explanation: In biology, axenic describes the state of a culture in which only a single SPECIES, variety, or STRAIN of organism is present and entirely FREE of all other contaminating organisms. Axenic culture is also an important tool for the study of symbiotic and parasitic organisms in a controlled manner.

The CORRECT choice is (a) Algorithm

The explanation is: Kalman FILTERING, also known as linear quadratic estimation (LQE), is an algorithm that uses a series of measurements observed over time, containing statistical NOISE and other inaccuracies, and produces estimates of unknown variables that tend to be more accurate than those based on a single MEASUREMENT alone, by estimating a joint probability distribution over the variables for each timeframe.

Right option is (d) Numerical values of coefficients

To elaborate: Traditionally, models are based on a combination of ‘theoretical’ relationships which PROVIDE the structure of the model, and experimental observations which provide the numerical values of coefficients. For biological processes, specifying the model structure can be difficult because of the complexity of cellular processes and the large NUMBER of environmental factors which affect cell CULTURE. Usually, bioprocess models are much-simplified approximate representations deduced from OBSERVATION rather than from theoretical laws of science. As an example, a frequently-used mathematical model for batch fermentation consists of the Monod equation for growth and an expression for rate of substrate consumption as a function of biomass concentration.

Correct answer is (B) False

Easy explanation: INDUSTRIAL fermenters can be divided into TWO major classes, anaerobic and AEROBIC. Anaerobic fermenters require little special equipment except for removal of heat generated during the fermentation process, whereas aerobic fermenters require much more elaborate equipment to ensure that mixing and adequate aeration are achieved.

Right answer is (a) True

For explanation I WOULD say: Large airlift reactors with capacities of thousands of CUBIC metres have been constructed. Tall internal-loop AIRLIFTS built underground are known as deep- shaft reactors; very high hydrostatic PRESSURE at the bottom of these vessels considerably improves gas-liquid mass-transfer. The height of airlift reactors is typically about 10 times the diameter; for deep-shaft systems the height-to-diameter RATIO may be increased up to 100.

Correct option is (a) True

Best EXPLANATION: Aerobic REACTIONS are not batch operations in the strictest sense; the low SOLUBILITY of oxygen in aqueous media means that it must be supplied continuously while CARBON DIOXIDE and other off-gases are removed.

Correct option is (a) True

Easy explanation: Depth filters do not perform well if there are large fluctuations in flow rate or if the air is wet; liquid condensing in the filter increases the pressure drop, causes channelling of the gas flow, and provides a PATHWAY for organisms to grow through the bed, Whereas, Membrane filter CARTRIDGES typically contain a pleated, hydrophobic filter with small and uniformly-sized pores 0.45 pm or less in diameter. The hydrophobic nature of the SURFACE minimises problems with filter wetting while the pleated CONFIGURATION allows a high filtration area to be packed into a small CARTRIDGE volume.

The correct option is (d) Trickle-bed

Easy explanation: Trickle bed reactors are a CLASS of packed bed reactors in which the MEDIUM flows (or trickles) over the solid particles. In these reactors, the particles are not immersed in the liquid. The liquid medium trickles over the surface of the SOLIDS on which the cells are immobilized.

The correct choice is (a) Liquid

The explanation is: DEEP bed filtration is a rapid and EFFICIENT method for removing SMALL particles from liquids. Such DISPERSIONS of particles in liquids are common in a wide RANGE of industries.

The correct choice is (a) Aerobic

Easy EXPLANATION: The Crabtree effect describes the phenomenon whereby the yeast, Saccharomyces cerevisiae, produces ethanol (alcohol) in aerobic conditions and high external glucose concentrations rather than producing biomass via the tricarboxylic acid (TCA) CYCLE, the usual PROCESS occurring aerobically in most yeasts e.g. Kluyveromyces spp. Increasing concentrations of glucose accelerates glycolysis (the breakdown of glucose) which results in the production of appreciable amounts of ATP through substrate-level phosphorylation. This reduces the need of oxidative phosphorylation done by the TCA cycle via the electron transport chain and therefore decreases oxygen CONSUMPTION.

The CORRECT CHOICE is (a) True

Easiest EXPLANATION: An actuator is a type of motor that is responsible for moving or controlling a mechanism or system. It is operated by a source of energy, typically electric current, hydraulic FLUID PRESSURE, or pneumatic pressure, and converts that energy into motion.

Correct CHOICE is (b) False

Easiest explanation: Bioreactor: A vessel that provides you the facility of carrying out a chemical PROCESS involving the ORGANISMS or biochemically active SUBSTANCES which are derived from such organisms is called a bioreactor. Fermentor: The device that is able to perform the process of fermentation is known as fermentor.

The CORRECT option is (a) True

Best explanation: A water-cooled CONDENSER is a heat EXCHANGER that removes heat from refrigerant vapor and transfers it to the water running through it. Having the refrigerant vapor CONDENSED on the outside of a tube does this. In doing so, the vapor CONDENSES and gives up heat to the water running inside the tube.

Correct choice is (b) False

To EXPLAIN I would say: Development of a comprehensive model covering all key aspects of a particular bioprocess and able to predict the effects of a wide range of culture variables is a DEMANDING exercise. Accurate models applicable to a range of process conditions are rare. As many aspects of fermentation are poorly under- stood, it difficult to devise mathematical models covering these areas. For EXAMPLE, the response of cells to spatial variations in dissolved-oxygen and substrate levels in fermenters, or the effect of impeller design on microbial growth and productivity, is not generally INCORPORATED into models because the SUBJECT has been inadequately studied.

Correct OPTION is (a) True

Explanation: COMMON DESIGNS such as simple gate and globe valves have a tendency to leak around the valve stem and accumulate broth solids in the closing mechanism. Although used in the fermentation industry, they are unsuitable if a high LEVEL of sterility is REQUIRED.

The correct ANSWER is (b) False

Easy explanation: Airlift reactors generally PROVIDE better mixing than bubble columns except at low liquid velocities. The airlift CONFIGURATION confers a degree of stability to liquid flow compared with bubble columns; therefore, higher gas flow RATES can be used without INCURRING operating problems such as slug flow or “spray formation”.

Correct choice is (b) False

Easy explanation: A Depth Filter is a filter consisting of either multiple layers or a single layer of a medium having depth, which CAPTURES contaminants within its structure, as opposed to on the surface. Depth FILTERS typically have nominal pore size RATINGS, Whereas, Membrane filters or “MEMBRANES” are microporous plastic films with specific pore size ratings. ALSO known as screen, sieve or microporous filters, membranes retain particles or microorganisms larger than their pore size primarily by surface capture.

Correct option is (c) Transducer

The best explanation: The preferred biological material like enzyme is preferred for conventional methods like physical or membrane entrapment and non covalent or covalent binding. The preferred biological material is in contact with the transducer. To produce a bound analyte through the analyte binds to the biological material which produces the ELECTRICAL response to be measured. In some cases the analyte changed to a product and have some probability to ASSOCIATE with the RELEASE of heat, gases like oxygen, ELECTRONS or hydrogen ions.

The CORRECT option is (a) True

Easy explanation: COPPER and copper-containing materials must be AVOIDED in all parts of the FERMENTER contacting the culture because of its TOXIC effect on cells.

Correct option is (b) False

The explanation: Homogeneous flow occurs only at low gas flow RATES and when BUBBLES LEAVING the sparger are evenly distributed across the column cross-section. In homogeneous flow, all bubbles RISE with the same UPWARD velocity and there is no backmixing of the gas phase.

Right option is (c) Bubbles

For explanation: The sudden widening at the top of the REACTOR SLOWS the bubble velocity and thus disengages the bubbles from the liquid FLOW. Carbon-dioxide rich bubbles are thus prevented from entering the downcomer. The increase in area will also helps to stretch bubbles in foams, CAUSING the bubbles to burst. The AXIAL flow circulation caused by the draft tube also helps to reduce foaming.

Right answer is (b) Dilution rate

Easy explanation: The reverse of HRT is defined as dilution rate, for which if it is bigger than the growth rate of microbial CELLS in the REACTOR, the MICROBE will be washed out, and otherwise the microbe will be ACCUMULATED in the reactor. Either of these situations may result in the BREAKDOWN of the biological process happening in the reactor.

Right OPTION is (b) False

Best explanation: The AVERAGE size of the openings between pieces of the filter media are represented in MICRONS. For example, a 20-micron filter has larger openings than a 5-micron filter. Consequently, the 20-micron filter element will LET larger PARTICLES pass through the filter than the 5-micron media would.

Right CHOICE is (a) 15.6 m^3 h^-1

Easiest explanation: Yxs = 0.06 g g^-1; YPX = 7.7 g g^-1;μmax = 0.3 h^-1; Ks = 0.2 g^-1; MS = 2.2 g g^-1 h^-l; si = 12 g 1^-1; V=60 m^3. qp = 3.4 h^-1, YPS = Ypx Yxs = 0.46 g g^-1.

s = 1.5 g l^-1

The correct choice is (a) True

The best explanation: Liquid filtration is generally not as EFFECTIVE or reliable as heat sterilisation. Viruses and MYCOPLASMA are ABLE to pass through membrane filters; care must also be taken to prevent holes or tears in the membrane. Usually, filter-sterilised medium is incubated for a PERIOD of time before use to test its sterility.

Right option is (a) True

To explain: The Peclet number is a dimensionless number used in calculations INVOLVING convective heat TRANSFER. It is the ratio of the thermal ENERGY convected to the FLUID to the thermal energy conducted within the fluid.

The correct choice is (b) Axial dispersion

Explanation: Deviation from plug-flow behaviour is characterised by the degree of axial dispersion in the system, i.e. the degree to which MIXING occurs along the length or AXIS of the pipe. Axial dispersion is a CRITICAL factor affecting design of continuous sterilisers.

The correct option is (a) 1.56 m^3 h^-1

Explanation: For 98% SUBSTRATE conversion, SF = (0.02 SI) = 0.19 kg m^-3

Right choice is (b) False

Explanation: If the liquid contains contaminant particles in the form of flocs or PELLETS, TEMPERATURE gradients may DEVELOP. Because heat transfer within solid particles is slower than in liquid, the temperature at the centre of the solid will be lower than that in the liquid for some PROPORTION of the sterilising time. As a RESULT, cell death inside the particles is not as effective as in the liquid. Longer holding times are required to treat solid-phase substrates and media containing particles.

Correct answer is (a) True

Easy EXPLANATION: Proper adjustment of PID controllers usually provides excellent REGULATION of the measured variable. However, poorly TUNED controllers can de STABILIZE a process and cause continuous or accentuated fluctuations in culture conditions.

Correct option is (c) CELL-free medium

To EXPLAIN I would SAY: The flow injection analysis (FIA), a sample-handling technique for removing cell- free medium from the fermenter and DELIVERING a pulse of analyte to EX situ measurement devices.

Right answer is (d) m^3/d

Easiest explanation: HRT also known as hydraulic residence TIME is a measure of the average length of time that a SOLUBLE compound REMAINS in a CONSTRUCTED bioreactor. Hydraulic retention time is the volume of the aeration tank divided by the INFLUENT flow rate:

where HRT is hydraulic retention time (d) and usually expressed in hours (or sometimes days), the V is the volume of aeration tank or reactor volume (m^3), and is the influent flow rate (m^3/d).

The correct option is (c) Partial pressure

Easiest explanation: The partial pressure of oxygen molecules dissolved in a liquid, such as BLOOD plasma. TECHNICALLY the oxygen tension (or partial pressure of oxygen) is defined as the pressure which oxygen in a mixture of gases would exert if it were on its own. Weirdly, partial pressures/gas tensions are ALSO used to DESCRIBE dissolved gases, in the blood for example.

Right option is (C) 5.5 G l^-1

The explanation is: ASSUMING ETHANOL is not present in the feed, PI = 0. Steady-state product concentration is given by:

The correct choice is (b) MILLIGRAMS of oxygen CONSUMED per gram of VOLATILE suspended solids per hour

For explanation I would SAY: The SPECIFIC Oxygen Uptake Rate (SOUR), also known as the oxygen consumption or respiration rate, is defined as the milligram of oxygen consumed per gram of volatile suspended solids (VSS) per hour. This quick test has many advantages; rapid measure of influent organic load and biodegradability, indication of the presence of toxic or inhibitory wastes, degree of stability and condition of a sample, and calculation of oxygen demand rates at various points in the aeration basin.

The correct answer is (a) True

The EXPLANATION is: Up and down agitators are useful to avoid shear stress to the cells. These are done by INSTEAD of a traditional PROPELLER agitator, which requires an expensive motor and magnetic coupling. Vertical up and down motion is achieved by a motor together with an inexpensive membrane perfectly assure sterility and produce an efficient mixing without formation of a vortex (no BAFFLES needed). At the same time this type of mixing is GENTLER on cells and produces less foam.

Right answer is (c) Packed bed

For explanation: Aeration is generally accomplished in a separate vessel; if AIR is sparged directly into the bed, BUBBLE coalescence PRODUCES GAS pockets and flow CHANNELLING or maldistribution. Packed beds are unsuitable for processes which produce large quantities of carbon dioxide or other gases which can become trapped in the packing.

Right answer is (B) False

For explanation: MAXIMUM biomass yield from substrate is ACHIEVED at relatively low glucose concentrations in the presence of adequate oxygen; FERMENTATIVE metabolism occurs if the glucose concentration rises above a certain level even though oxygen may be present. Fermentative metabolism should be avoided for biomass production because the yield of CELLS is reduced as ethanol and carbon dioxide are formed as end-products.

Correct ANSWER is (b) Heterogeneous systems

Explanation: All bioreactors deal with heterogeneous systems dealing with two or more PHASES, e.g., liquid, gas, solid. Therefore, optimal conditions for FERMENTATION necessitate efficient transfer of mass, heat and momentum from ONE PHASE to the other.

The correct answer is (c) Nozzle sparger

To explain I WOULD say: Nozzle spargers are used in many agitated FERMENTERS from laboratory to production scale. These spargers consist of a SINGLE open or partially-closed pipe providing a stream of air bubbles; advantages compared with other sparger designs include low resistance to GAS flow and small RISK of blockage.