GATE Biotechnology Fundamentals of Biological Engineering Syllabus

Fundamentals of Biological Engineering syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Fundamentals of Biological Engineering in GATE Biotechnology, not a summary of it.

1. 1

   Engineering principles applied to biological systems

   4 topics

   • Material and energy balances for reactive and non-reactive systems
   • Recycle, bypass and purge processes
   • Stoichiometry of growth and product formation
   • Degree of reduction, electron balance and theoretical oxygen demand
2. 2

   Classical thermodynamics and Bioenergetics

   6 topics

   • Laws of thermodynamics
   • Solution thermodynamics
   • Phase equilibria, reaction equilibria
   • Ligand binding
   • Membrane potential
   • Energetics of metabolic pathways, oxidation and reduction reactions
3. 3

   Transport Processes

   7 topics

   • Newtonian and non-Newtonian fluids
   • Fluid flow - laminar and turbulent
   • Mixing in bioreactors, mixing time
   • Molecular diffusion and film theory
   • Oxygen transfer and uptake in bioreactor, kLa and its measurement
   • Conductive and convective heat transfer, LMTD, overall heat transfer coefficient
   • Heat exchangers

Fundamentals of Biological Engineering flashcards for GATE Biotechnology

19 of 56 cards from the Fundamentals of Biological Engineering deck — real questions with worked answers.

1. State the general material balance equation for any process system.

   $$\text{Accumulation} = \text{Input} - \text{Output} + \text{Generation} - \text{Consumption}$$ For a non-reactive system, generation and consumption are zero, so accumulation = input $-$ output. At steady state, accumulation $= 0$.

2. For a non-reactive system operating at steady state, what does the material balance reduce to?

   Input = Output (for total mass and for each chemical species), since accumulation, generation, and consumption are all zero.

3. What is the general energy balance equation (open system, first law)?

   $$\frac{dE}{dt} = \dot{Q} - \dot{W}_s + \sum_{in}\dot{m}\left(h + \frac{u^{2}}{2} + gz\right) - \sum_{out}\dot{m}\left(h + \frac{u^{2}}{2} + gz\right)$$ Neglecting kinetic/potential terms at steady state: $\dot{Q} - \dot{W}_s = \Delta(\dot{m}h)$.

4. In a process flow diagram, define a recycle stream.

   A recycle stream returns part of the output of a unit back to the inlet (upstream) to be reprocessed. It improves overall conversion and reactant utilization. The overall (system) conversion exceeds the single-pass conversion.

5. Distinguish single-pass conversion from overall conversion in a reactor with recycle.

   Single-pass conversion $= \dfrac{\text{reactant consumed in one pass through reactor}}{\text{reactant fed to reactor inlet}}$. Overall conversion $= \dfrac{\text{reactant consumed}}{\text{fresh feed of reactant}}$. With recycle, overall $>$ single-pass.

6. What is the purpose of a bypass stream?

   A bypass diverts a fraction of the feed around a process unit and recombines it with the unit's outlet. It is used to control/adjust the composition or properties (e.g., temperature, concentration) of the final product stream.

7. Why is a purge stream required in a recycle loop?

   A purge stream removes a small portion of the recycle to prevent accumulation (buildup) of inert or unwanted species that would otherwise concentrate indefinitely in the loop. At steady state, rate of inert entering with fresh feed = rate leaving in purge.

8. Write a representative stoichiometric equation for aerobic microbial growth on a carbon source with ammonia as nitrogen source.

   $$\ce{CH_xO_y + a\,O2 + b\,NH3 -> c\,CH_pO_nN_q + d\,CO2 + e\,H2O}$$ where $\ce{CH_pO_nN_q}$ is the elemental formula of biomass (typically $\ce{CH_{1.8}O_{0.5}N_{0.2}}$).

9. What is the typical elemental composition (formula) of dry microbial biomass, and its formula weight per C-mole?

   Approximately $\ce{CH_{1.8}O_{0.5}N_{0.2}}$, with a formula weight of about $24.6\ \text{g per C-mol}$ (ash-free).

10. Define the biomass yield coefficient $Y_{X/S}$.

    $$Y_{X/S} = \frac{\text{mass (or C-mol) of biomass produced}}{\text{mass (or mol) of substrate consumed}} = -\frac{\Delta X}{\Delta S}$$ It quantifies the efficiency of converting substrate into cell mass.

11. Define the respiratory quotient (RQ) in fermentation.

    $$RQ = \frac{\text{moles } \ce{CO2} \text{ produced}}{\text{moles } \ce{O2} \text{ consumed}}$$ It is used to monitor metabolic state and to close elemental balances on-line.

12. Define the degree of reduction $\gamma$ of a compound.

    The degree of reduction is the number of equivalents of available electrons per C-atom transferred to oxygen on combustion to $\ce{CO2}$, $\ce{H2O}$, and $\ce{NH3}$. Reference valences: $C=+4$, $H=+1$, $O=-2$, $N=-3$.

13. Calculate the degree of reduction of glucose ($\ce{C6H12O6}$).

    $$\gamma = \frac{1}{C}\big(4\,n_C + 1\,n_H - 2\,n_O\big) = \frac{4(6)+1(12)-2(6)}{6} = \frac{24}{6} = 4$$ So $\gamma_{glucose} = 4$ per carbon.

14. What is the degree of reduction of typical biomass $\ce{CH_{1.8}O_{0.5}N_{0.2}}$ (with $\ce{NH3}$ as N reference)?

    $$\gamma_X = 4(1) + 1(1.8) - 2(0.5) - 3(0.2) = 4 + 1.8 - 1.0 - 0.6 = 4.2$$

15. State the electron (degree-of-reduction) balance for aerobic growth relating substrate, oxygen, biomass, and product.

    $$\gamma_S = \gamma_X\, Y_{X/S} + \gamma_P\, Y_{P/S} + 4\, Y_{O/S}$$ Oxygen has $\gamma = -4$ per $\ce{O2}$ (it accepts 4 electrons), giving the $4\,Y_{O/S}$ term as electrons going to $\ce{O2}$.

16. How is theoretical oxygen demand (ThOD) computed from degree of reduction?

    Each mole of $\ce{O2}$ accepts 4 electron equivalents, so $$\text{ThOD} = \frac{\gamma_S}{4}\ \text{(mol }\ce{O2}\text{ per C-mol substrate fully oxidized)}.$$ In mass terms, ThOD $= 8 \times$ (electron equivalents) g $\ce{O2}$.

17. State the first law of thermodynamics for a closed system.

    $$\Delta U = Q - W$$ The change in internal energy equals heat added to the system minus work done by the system. Energy is conserved.

18. State the second law of thermodynamics in terms of entropy.

    For any spontaneous (real) process in an isolated system, the total entropy increases: $$\Delta S_{univ} = \Delta S_{sys} + \Delta S_{surr} \geq 0$$ Equality holds only for reversible processes.

19. State the third law of thermodynamics.

    The entropy of a perfect crystalline substance approaches zero as the temperature approaches absolute zero: $$\lim_{T \to 0}S = 0$$ This provides an absolute reference for entropy.

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