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Right option is (a) True

The EXPLANATION is: A generation time is simply the time it takes for one CELL to become two. When growing exponentially by binary fission, the INCREASE in a bacterial population is by geometric progression. If we start with one cell, when it DIVIDES, there are 2 cells in the first generation, 4 cells in the SECOND generation, 8 cells in the third generation, and so on. The generation time is the time interval required for the cells (or population) to divide.

Right OPTION is (c) kg m^-3s^-1

Easy explanation: Rate of cell GROWTH is described by the equation:

rX = μx

where rX is the VOLUMETRIC rate of BIOMASS production with units of, for example, kg m^-3 s^-I, x is viable cell CONCENTRATION with units of, for example, kg m^-3, and μ is the specific growth rate. Specific growth rate has dimensions T^-1.

The CORRECT answer is (b) False

Easy explanation: Km reflects the enzyme’s dissociation constant. A high Km means WEAK binding (the enzyme LIKES to dissociate from its SUBSTRATE), and a low Km means strong binding (it doesn’t LIKE to dissociate from its substrate, meaning that it has a strong affinity for the substrate).

Correct choice is (d) kg mol m^-3

To EXPLAIN: Km is the MICHAELIS CONSTANT for reactant A. Km has the same DIMENSIONS as CA. Typical units for Vmax are kgmol m^-3 s^-I; typical units for Km are kgmolm^-3.

The correct ANSWER is (b) Lesser than the lag phase

To explain I would say: During this phase bacteria divides continuously at constant RATE and the number of bacteria INCREASE exponentially. In this phase all bacteria are in their rapid STAGE of cell division and show balanced growth. DUE to rapid cell division, bacteria have smallest size in this phase.

The correct choice is (b) False

Easiest explanation: The RATE of an enzymatic REACTION will INCREASE as SUBSTRATE concentration increases, and that INCREASED unbinding of enzyme-substrate complexes will decrease the reaction rate.

Correct choice is (d) Reactions increase with increase in TEMPERATURE

Best EXPLANATION: As reactions proceed, the concentrations of reactants decrease. In general, rate of reaction depends on reactant concentration so that the specific rate of conversion decreases simultaneously. Reaction rate ALSO varies with temperature; most reactions speed up considerably as the temperature RISES.

The correct option is (b) 0.125 M

Explanation: MV = grams / molar mass

(X) (0.4000 L) = 5.30 g / 105.988 g mol^-1

0.12501415 M

x = 0.125 M (to three SIG figs).

Right option is (c) 12 grams

To elaborate: A sample of 12 grams of carbon is EQUAL to one mole. The amount of moles in a substance can be determined USING that substance’s molar mass. The molar mass is the amount of grams in one mole of a substance. The molar mass is the AVERAGE ATOMIC mass for a substance.

The correct answer is (a) Competitive inhibition

The best I can explain: When a fake SUBSTRATE BINDS to the active site of an enzyme, it can’t be processed in the same WAY and it won’t turn into a product. A fake substrate is called a competitive inhibitor. Competitive inhibitors bind the active site of an enzyme, preventing a real substrate from binding and a product from being FORMED.

The CORRECT option is (b) False

Explanation: For irreversible reaction GIBBS free energy CHANGE will be less than zero ΔG < 0 is the condition for the irreversible reaction. Irreversible reaction normally takes place in an OPEN vessel.

The correct ANSWER is (a) ZERO order

Explanation: V ≈ vmax

Therefore, at high substrate concentrations, the reaction rate approaches a constant VALUE independent of substrate concentration; in this concentration range, the reaction is essentially zero order with RESPECT to the substrate.

The correct OPTION is (b) Half SATURATION constant

For explanation I would SAY: Ks is the half-saturation constant or SHAPE FACTOR of the Monod equation. Ks equals the substrate concentration (mg/L) at which μ equals 1/2 of μmax.

Right choice is (b) PRE- Steady state

Best explanation: In the first moment after an ENZYME is MIXED with substrate, no PRODUCT has been formed and no INTERMEDIATES exist. The study of the next few milliseconds of the reaction is called pre-steady-state kinetics.

Right choice is (B) mol/sec

The explanation: vmax “REPRESENTS the maximum rate ACHIEVED by the SYSTEM, at maximum (saturating) SUBSTRATE concentrations”, Unit: μmol/min (or mol/s).

The CORRECT CHOICE is (a) 0.133

Easiest explanation: v = VMAX[S] / (KM + [S])

= 0.2×10 / (5+10)

= 0.133.

Right answer is (a) True

To explain I would say: The GROWTH rate can be expressed in terms of mean growth rate constant (k), the number of generations PER unit time. Mean GENERATION time or mean doubling time (g), is the time taken to DOUBLE its SIZE.

Right ANSWER is (a) Chemostat

To elaborate: A chemostat (from chemical environment is static) is a bioreactor to which fresh medium is continuously added, while culture liquid containing left over nutrients, METABOLIC end products and MICROORGANISMS are continuously removed at the same rate to keep the culture volume constant.

The CORRECT option is (a) True

Explanation: Growth for multicelluar organisms is TYPICALLY measured in TERMS of the increase in size of a single organism, MICROBIAL growth is measured by the increase in population, either by measuring the increase in CELL number or the increase in overall mass. Cell division process begins with cell elongation, which requires careful enlargement of the cell membrane and the cell wall, in addition to an increase in cell volume.

Right option is (d) h^-1

Explanation: Specific growth rate = μ = \(\frac{1}{X} \frac{dX}{dt}\)

where, X = cell MASS concentration (g/L)

t = time (h).

Correct answer is (a) Complete INHIBITION

For explanation: Linear inhibition is sometimes called complete inhibition, and the contrasting term partial inhibition is sometimes USED for a type of non-linear inhibition in which saturation with inhibitor does not decrease the rate to zero. These latter TERMS are discouraged because they can be misleading, implying, for EXAMPLE, that the rate may indeed be decreased to zero in ‘complete inhibition’ at non-saturating concentrations of inhibitor.

Correct option is (b) False

The BEST I can explain: Reaction THEORY has two fundamental parts: reaction thermodynamics and reaction kinetics. Reaction thermodynamics is concerned with how far the reaction can PROCEED; no matter how fast a reaction is, it cannot continue beyond the point of CHEMICAL equilibrium. On the other hand, reaction kinetics is concerned with the rate at which reactions proceed.

Right choice is (a) ARRHENIUS equation

Explanation: Temperature has a significant kinetic effect on reactions. Variation of the RATE constant k with temperature is described by the Arrhenius equation:

k = A e^-E/RT

Where, k is the rate constant, A is the Arrhenius constant or frequency factor, E is the activation energy for the REACTION, R is the ideal gas constant, and T is absolute temperature. According to the Arrhenius equation, as T increases, k increases exponentially.

Taking the natural LOGARITHM of both sides of equation:

Thus, a plot of ln k versus 1/T gives a straight line with slope -E/R . For many reactions the value of E is positive and large, indicating a rapid increase in reaction rate with temperature.

Right option is (a) Cells are in small amount

Easiest EXPLANATION: GROWTH ALWAYS appears much slower at the beginning of CULTURE because the number of cells present is small.

The correct OPTION is (d) -238.15

Explanation: CONVERT degree KELVIN (K) into TEMPERATURES using this equation:

T(°C) = T(K) – 273.15

= -238.15°C.

Correct option is (d) Autocatalysis

For explanation I would SAY: Cell growth is an autocatalytic reaction: this MEANS that the catalyst is a product of the reaction. The performance of catalytic reactions is characterized by variables such as the reaction rate and yield of product from SUBSTRATE. In bioreactors, the growth is autocatalytic in that the more CELLS you have, the greater the growth rate.

The correct choice is (d) 0.29 g BIOMASS / g substrate

Best EXPLANATION: YIELD = (6.0 – 0.2 g biomass) / (20 g substrate) = 0.29 g biomass / g substrate.

The correct choice is (b) THEORETICAL yields

Best EXPLANATION: Theoretical yields are SOMETIMES REFERRED to as maximum POSSIBLE yields because they represent the yield in the absence of competing reactions.

Correct ANSWER is (d) 2.498 M

For explanation I would say: MV = grams / molar MASS

(x) (1.000 L) = 245.0 g / 98.0768 g mol^-1

x = 2.49804235 M

to FOUR sig figs, 2.498 M.

Right answer is (a) Line-weaver BURK plot

For explanation I would say: The double-reciprocal equation is obtained by taking the reciprocal of both sides of the Michaelis-Menten equation. The double-reciprocal (also known as the Lineweaver-Burk) plot is created by plotting the inverse initial velocity (1/V0) as a function of the inverse of the SUBSTRATE concentration (1/[S]). The vmax can be accurately DETERMINED and thus KM can also be determined with ACCURACY because a STRAIGHT line is formed. The slope of the resulting line is KM/vmax, the y-intercept is 1/vmax, and the x-intercept is -1/KM.

Correct answer is (d) DEATH PHASE

Best explanation: In death phase, the cells LOSE VIABILITY and LYSE. Therefore, μ=0.

Right OPTION is (a) True

Easy explanation: K in 50°C is 0.98 and K in 75°C is 1.15.As K increases, the fraction of fructose in the equilibrium mixture increases. Therefore, from an equilibrium POINT of view, it is more DESIRABLE to operate the reactor at 75°C. HOWEVER, other factors such as ENZYME deactivation at high temperatures should also be considered.

The correct choice is (a) Initial

Explanation: Typically, only initial rate data are used. This means that several batch experiments are carried out with different initial substrate concentrations; from each set of data the reaction rate is evaluated at time zero. Initial RATES and corresponding initial substrate concentrations are used as (V, s) pairs which can then be PLOTTED in various ways for determination of vmax and Km. Initial rate data are preferred for ENZYME REACTIONS because experimental conditions such as enzyme and substrate concentrations are known most accurately at the start of the reaction.

Right choice is (b) False

To explain I would say: TOTAL, volumetric and specific productivities are interrelated concepts in process design. For example, high total productivity COULD be achieved with a CATALYST of low specific activity if the reactor is loaded with a high catalyst concentration. If this is not possible, the volumetric productivity will be relatively low and a larger reactor is required to achieve the desired total productivity.

Correct option is (c) Temperature

The BEST I can explain: The value of K depends on temperature as follows:

where, ΔG°rxn is the CHANGE in standard free energy per mole of A reacted, R is the ideal gas constant and T is ABSOLUTE temperature.

The CORRECT choice is (c) Stationary phase

To explain: When microbes lack the nutrients necessary for growth, they ENTER stationary phase. In cases when energy sources are still present in the environment, they must decide whether to continue to use their metabolic program to harvest the available energy. Here we characterized the metabolic response to a VARIETY of TYPES of nutrient starvation in ESCHERICHIA coli and Bacillus subtilis.

Right answer is (a) No change in number, but an increase in mass

To explain I would say: The lag phase is the time period when there is no IMMEDIATE increase in cell number of microorganisms as they are introduced into fresh culture medium. The microorganisms during this phase are TRYING to acclimatize to the new culture medium as it may be different from the PREVIOUS one in which the microorganism was growing. Typically cells in the lag period are synthesizing RNA, enzymes, and essential metabolites that might be missing from their new environment (such as growth factors or macromolecules), as well as adjusting to environmental changes such as changes in TEMPERATURE, pH, or oxygen availability. They can also be undertaking any necessary repair of injured cells.

The correct CHOICE is (a) conc^-1 time^-1

For explanation I would say: When calculating Kcat, the concentration units cancel out, so Kcat is expressed in units of INVERSE time. It is the turnover number – the number of substrate molecule each enzyme site converts to PRODUCT per unit time. The units of Km are those of concentration i.e. mM, mM or Km is the concentration of substrate at which HALF maximal VELOCITY is observed.

Correct OPTION is (c) Michaelis-menten plot

Easiest explanation: This simple procedure involves PLOTTING (v, s) values directly vmax is the rate as s→∞ and KM is the value of s at v = vmax/2. The accuracy of this method is usually poor because of the difficulty of EXTRAPOLATING to vmax.

Right answer is (B) SPECIFIC rate

Easiest explanation: In specific rate, biological REACTIONS involve enzyme and cell catalysts. Because the total rate of conversion depends on the amount of catalyst present, it is sometimes USEFUL to specify reaction rate as the rate per quantity of enzyme or cells INVOLVED in the reaction.