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The CORRECT CHOICE is (d) First-zero order kinetics

Easiest explanation: Biochemical reactions involving a single substrate are often assumed to follow Michaelis–Menten kinetics, without regard to the model’s underlying assumptions. The Michaelis-Menten relationship for the effect of substrate concentration on the rate of an ENZYME catalysed reaction is given by the equation:

\(V = \frac{V_{max}S}{(S+K_m)}\)

where V = rate of reaction, Vmax = maximal rate of reaction, S = substrate concentration, and Km = substrate concentration at which reaction rate = 0.5 Vmax.

The analogous Monod equation for effect of substrate concentration on the specific growth rate of a microorganism is as FOLLOWS:

\(\mu = \frac{\mu_{max}S}{(S+K_s)}\)

where μ = specific growth rate, μmax = maximum specific growth rate in absence of substrate limitation, S = concentration of growth limiting substrate, Ks = substrate concentration which allows the organism to grow at 0.5 μmax.

Right answer is (b) Any material with UNIFORM composition

The best I can explain: “HOMOGENEOUS material” MEANS one material of uniform composition THROUGHOUT or a material, consisting of a combination of materials, that cannot be disjointed or separated into different materials by mechanical actions such as unscrewing, cutting, CRUSHING, grinding and abrasive processes.

Right choice is (a) Growth associated

The best EXPLANATION: Growth associated is produced at the same time as cell growth which CONSTITUTES of CONSTITUTIVE enzymes (ONES that are normally present) and metabolic INTERMEDIATES.

The correct answer is (B) False

The EXPLANATION: (YPX) is defined as MASS or mole of PRODUCT produced per unit mass or mole of Biomass formed.

Right option is (C) kg substrate (kg biomass)^-1 S^-1

Easy explanation: A maintenance COEFFICIENT is USED to describe the specific rate of substrate uptake for cellular maintenance, or

m = – [dS/dt]m/X

Unit of maintenance coefficient , m. is kg substrate (kg biomass)^-1S^-1.

Right option is (d) Conductometry

To elaborate: The conductivity METHOD of measuring growth kinetics of plant CELL lines was used especially with the purpose of bioprocess engineering applications of plant cell cultures. The major advantages of using conductometry as the biosensing TECHNIQUE for measurement of plant cell growth kinetics are:

i) The method is very economical and efficient

ii) It gives accurate, reliable and reproducible measurements, while amenable to continuous online monitoring and PROCESS control.

iii) It is a noninvasive method which does not ADVERSELY affect the plant cells or the bioreactor operation.

Correct choice is (a) 0.099 G substrate/g DCW^-h

To EXPLAIN: 10% of the substrate goes to MAINTAINING the cells.

m = (10 g substrate/l.0.10)/(1.81 g DCW/L.5.63 HR)

= 0.099 g substrate/g DCW^-h.

Correct answer is (a) Continuous PROCESS

Explanation: In continuous process steady state CONDITION is maintained, in which

– The RATE of increase of cell biomass with time is equal to zero.

– The TOTAL number of CELLS are constant and

– The total volume in the bioreactor are constant.

Correct option is (a) Growth associated

Easiest explanation: The CONSTITUTIVE ENZYMES are growth associated as they are produced at the same time as cell growth. FACTORS which are REQUIRED for the growth of the ORGANISM is the key aspect.

The correct answer is (d) Monad equation

To elaborate: The decrease in growth rate and the cessation of growth due to the depletion of SUBSTRATE, may be DESCRIBED by the relationship between μ and the residual growth limiting substrate. This relationship is represented by an equation GIVEN by Monad in1942 which is KNOWN as Monad equation.

The CORRECT answer is (b) False

Explanation: There is substrate UPTAKE as long as there is external substrate available; when the substrate is exhausted MAINTENANCE energy is GENERALLY SUPPLIED by endogenous metabolism.

The correct answer is (b) Non-growth associated

The explanation: ATP is also required for other activities called MAINTENANCE.

 – CELL motility

 – turnover of cellular components

 – ADJUSTMENT of MEMBRANE POTENTIALS and internal pH

These are non-growth associated mechanisms.

The CORRECT OPTION is (c) High affinity for the limiting substrate

To explain: If the organism has a very high affinity for the limiting substrate (a low Ks VALUE) the growth rate will not be affected until the substrate CONCENTRATION has declined to a very low level. Thus, the deceleration PHASE for such a culture would be short.

Right choice is (b) Non-growth associated

Explanation: Non-growth associated TAKES PLACE during stationary PHASE (μ=0) and which CONSTITUTES of secondary metabolites such as ANTIBIOTICS.

The correct answer is (b) False

Easiest explanation: Difference between the TWO TYPES of kinetics (MONOD and Michaelis-Menten):

– Michaelis-Menten – quantity of reactive material (enzyme) is constant

– Monod – quality of reactive material (cells) is INCREASING.

Right OPTION is (c) Limiting reactant

The explanation is: The same thing happens in chemical reactions: there is ALWAYS a limiting reactant, which is a chemical element or substance that limits the amount of PRODUCT made during a chemical REACTION. Typically, there is also an excess reactant, or the amount of an element or substance left over after the reaction STOPS.

Correct OPTION is (d) Stationary PHASE

For explanation I WOULD say: The stationary phase in batch culture is that point where the growth rate has declined to ZERO. This phase is also known as the maximum population phase.

Right answer is (a) Batch FERMENTER and fed-batch process

For explanation I would say: It requires a batch fermenter, and a fed batch process is NORMALLY USED to PROLONG the stationary period and so INCREASE production.

Correct answer is (b) False

To explain: If all the reagents are ADDED in exactly the right mole ratio then all of each reagent is used up, so there is no excess or limiting reagent. In this CASE you can use either reagent MOLES to work out the amount of product FORMED. Then both reagents will be fully consumed so neither is limiting.

The CORRECT ANSWER is (b) False

Explanation: EFFECT of incorporating maintenance terms gives observed YIELD rather than theoretical yields and accounts for unusual behavior, i.e. negative ASSOCIATION with growth.

Correct choice is (a) Aerobic

For EXPLANATION: PENICILLIN was the first IMPORTANT commercial product produced by an aerobic, submerged fermentation. Penicillin is produced by the fungus Penicillium chrysogenum which requires lactose, other sugars, and a source of nitrogen (in this case a yeast extract) in the medium to grow well.

The correct choice is (a) True

The best I can explain: Kinetic EXPRESSIONS requires both growth-associated and maintenance-associated production.

rP = qpx

rP = (YP/X μ + MP)X

qP = (YP/X μ + mP)

Where,

YP/X is the theoretical yield of product from biomass, mp is the specific rate of product FORMATION DUE to maintenance, and x is biomass concentration.

Correct answer is (a) Lactic acid

Explanation: Lactic acid comes under the first category of the class of metabolite that represents PRODUCTS directly associated with GENERATION of energy in the cell. Compounds in the first category are formed directly as end- or by-products of energy METABOLISM; these materials are synthesised in PATHWAYS which produce ATP. Examples include: Ethanol, acetic acid, gluconic acid, acetone, BUTANOL, lactic acid, other products of anaerobic fermentation.

The correct choice is (b) False

Easiest explanation: In some cultures there is no extracellular PRODUCT formation; for example, biomass itself is the product in manufacture of bakers’ YEAST and single-cell PROTEIN. In the absence of product formation, we assume that all substrate entering the cell is used for growth and MAINTENANCE functions.

The correct answer is (d) STATIONARY phase

Easiest explanation: LIKE all antibiotics, penicillin is a secondary METABOLITE, so is only PRODUCED in the stationary phase.

Correct answer is (a) Penicillin

The explanation: FORMATION of other PRODUCTS such as antibiotics involves reactions far removed from energy metabolism and the class of METABOLITE related to products for which there is no clear direct or indirect coupling to energy generation has the examples INCLUDING that of antibiotics such as: Penicillin, STREPTOMYCIN, vitamins.

Correct option is (c) Second ORDER KINETICS

To explain I would say: The yield coefficient, commonly referred to as the substrate-to-biomass yield, is used to convert between cell growth RATE dX/dt and substrate utilization rate dS/dt. The yield coefficient and the specific growth rate used to develop three types of MICROBIAL growth kinetic relationships; Monod, first order, and zero order kinetics.

The correct choice is (b) Conversion of amount of substrate into product

For explanation I WOULD say: When all enzyme is bound to substrate KCAT, the TURNOVER number, is the maximum number of substrate molecules converted to product per enzyme molecule per second. Further ADDITION of substrate does not increase the rate which is said to be SATURATED.

Correct option is (a) K DECREASES with INCREASING temperature

For explanation I would say: For EXOTHERMIC reactions with negative ΔH°rxn, K decreases with increasing temperature. For endothermic reactions and POSITIVE ΔH°rxn , K increases with temperature.

The correct OPTION is (a) kcat/KM

To explain I WOULD SAY: The constant kcat/KM (catalytic EFFICIENCY) is a measure of how efficiently an enzyme converts a substrate into product.

Right choice is (b) False

To elaborate: The specific growth rate of CELLS is dependent on the CONCENTRATION of NUTRIENTS in the medium. Often, a single substrate exerts a dominant INFLUENCE on rate of growth; this component is known as the growth-rate-limiting substrate or, more SIMPLY, the growth-limiting substrate. The growth-limiting substrate is often the carbon or nitrogen source, although in some cases it is oxygen or another oxidant such as nitrate.

The correct choice is (c) 1.30 G g^-1

Easy explanation: THEORETICAL yield is based on the MASS of ETHANOL actually used for synthesis of ACETIC acid. From the stoichiometric equation:

Correct option is (a) increase and the division rate increases to REACH a maximum

Easy EXPLANATION: This is a BRIEF transient period during which cells START growing SLOWLY. In fact, acceleration phase connects the lag phase and log phase.

Right choice is (c) Growth PHASE

For EXPLANATION I WOULD say: In growth phase, Growth ACHIEVES its maximum rate. THEREFORE, μ ≈ μmax.

Correct ANSWER is (a) 0.94 G g^-1

Easy explanation: Using a basis of I LITRE, the observed YIELD over the entire culture period is obtained from equation:

The correct CHOICE is (b) Isoenzymes

To explain I would SAY: Isozymes (also known as isoenzymes or more generally as multiple forms of ENZYMES) are enzymes that differ in AMINO acid sequence but catalyze the same chemical reaction. These enzymes usually display different kinetic parameters (e.g. different KM values), or different REGULATORY properties. Allozymes represent enzymes from different alleles of the same gene, and isozymes represent enzymes from different genes that process or catalyse the same reaction, the two words are usually used interchangeably.

Correct answer is (b) SUBSTRATE binding may induce a conformational change in the enzyme, which then BRINGS catalytic groups into proper orientation

Explanation: Induced-fit MODEL A proposed mechanism of interaction between an enzyme and a substrate. It postulates that exposure of an enzyme to a substrate CAUSES the active site of the enzyme to change shape in order to allow the enzyme and substrate to BIND.

The CORRECT choice is (a) True

Easiest explanation: The REACTION rate STILL increases with increasing substrate concentration, but levels off at a much lower rate. By increasing the enzyme concentration, the maximum reaction rate greatly increases. However, enzymes become SATURATED when the substrate concentration is high.

The correct option is (c) In units of activity

To elaborate: The mass of a particular enzyme added to a reaction is rarely known; most commercial enzyme PREPARATIONS contain SEVERAL components in unknown and variable proportions depending on the BATCH obtained from the manufacturer. To overcome these difficulties, enzyme quantity is often expressed as units of activity measured under specified conditions. One unit of enzyme is usually taken as the amount which catalyses conversion of 1μmol substrate per minute at the optimal TEMPERATURE, pH and substrate concentration.

The correct answer is (d) GMOL / gmol

Easy explanation: The THEORETICAL yield is the amount predicted by a stoichiometric calculation based on the number of moles of all reactants present. This calculation assumes that only ONE reaction occurs and that the limiting reactant REACTS completely.

Right option is (c) Spectrophotometer

The explanation: A spectrophotometer optically determines the absorbance or transmission of CHARACTERISTIC wavelengths of radiant energy (light) by a CHEMICAL species in solution. Each molecule absorbs light at CERTAIN wavelengths in a unique SPECTRAL pattern because of the number and arrangement of its characteristic functional groups, such as double bonds between carbon atoms. According to the Beer-Lambert law, the amount of light ABSORBED at these wavelengths is directly proportional to the concentration of the chemical species.