GATE BT 2020 • Q23
MCQ • 1 Mark
Section 4: Bioprocess Engineering and Process Biotechnology
Mass transfer in bioprocesses (kLa)
Subtopic: Fundamentals of Mass transfer in bioprocesses (kLa)
Question Statement:
Which one of the following media components is used to maintain pH in
mammalian cell culture?
Options:
-
(A) CaCl
-
(B) MgSO4
-
(C) NaCl
-
(D) NaHCO3
Step-by-Step Solution & Explanation
### **Official Solution & Concept Analysis (GATE BT 2020 Q.23)**
**1. Governing Concept**:
- **Topic**: Animal Cell Culture & Physiological Buffering
- In mammalian cell culture:
- The standard buffering system consists of **Sodium bicarbonate ($\text{NaHCO}_3$)** in equilibrium with gaseous carbon dioxide ($\text{CO}_2$, typically $5\% \text{ CO}_2$ in humidified incubators):
$\text{CO}_2 + \text{H}_2\text{O} \rightleftharpoons \text{H}_2\text{CO}_3 \rightleftharpoons \text{H}^+ + \text{HCO}_3^-$
- This bicarbonate-carbonic acid buffer maintains the culture medium at the physiological pH of $7.2 - 7.4$.
**2. Option Analysis**:
- **Option (A) [CaCl2] is INCORRECT**: Divalent cation source for cell adhesion and signaling.
- **Option (B) [MgSO4] is INCORRECT**: Magnesium ion source for cellular enzymatic cofactors.
- **Option (C) [NaCl] is INCORRECT**: Osmotic pressure maintenance agent.
- **Option (D) [NaHCO3] is CORRECT**: The primary buffering component maintaining pH in $\text{CO}_2$-incubated animal cell cultures.
**3. Final Answer**:
- **Correct Choice**: **D**
Practice This in Real CBT Exam Interface
Test yourself with the official TCS-iON palette, virtual calculator, and immediate performance analytics.
Launch CBT Mock Test