UPSC Prelims 2021 Q69: Science & Technology – Health & Diseases
- (a) 1 and 2 only
- (b) 2 and 3 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
Answer: (a) 1 and 2 only
Explanation
Which Microbes Can Be Cultured in Synthetic Medium?
| Microbe | Can Be Cultured in Artificial Medium? | Reason |
|---|---|---|
| 1. Bacteria | YES | Most bacteria grow in nutrient agar, LB broth, MacConkey agar and other defined synthetic media. |
| 2. Fungi | YES | Fungi (yeasts, moulds) grow well on Sabouraud Dextrose Agar, Potato Dextrose Agar, YPD. Widely cultured. |
| 3. Virus | NO | Viruses are obligate intracellular parasites - they can only replicate inside living host cells (tissue culture, embryonated eggs, animal models). Cannot grow on cell-free synthetic media. |
Only bacteria and fungi can be cultured in artificial/synthetic media. Viruses need living cells. Answer: (a) 1 and 2 only.
Answer: (a) 1 and 2 only.
Why each option is right or wrong
- (a) CORRECT. Bacteria (1) and Fungi (2) can be cultured in synthetic/artificial media (nutrient agar, LB, Sabouraud, PDA). Viruses (3) cannot - they are obligate intracellular parasites needing live host cells.
- (b) Incorrect. Viruses cannot grow on synthetic media - they need living cells.
- (c) Incorrect. Fungi (2) also grow on synthetic media; viruses (3) do not.
- (d) Incorrect. Viruses cannot be cultured on artificial media.
Key point
Bacteria + Fungi = culturable on synthetic media (nutrient agar, LB, Sabouraud, PDA). Viruses = OBLIGATE INTRACELLULAR PARASITES - need living host cells (tissue culture, embryonated eggs, animal models). Answer: 1 and 2.
Remember
Bacteria (1) and Fungi (2) can be cultured in artificial/synthetic media (nutrient agar, Sabouraud, etc.). Viruses (3) CANNOT be cultured on artificial media - they are obligate intracellular parasites requiring living host cells. Answer: (a) 1 and 2 only.
Common mistakes
- Assuming all microbes can be cultured in a Petri dish. Viruses need living cells - they are not free-living.
- Not knowing SARS-CoV-2 was cultured in Vero cells (kidney cells of African green monkey) for vaccine development.
- Confusing tissue culture (host cells + medium) with pure synthetic culture.
Exam tip
Culturing microbes: Bacteria (nutrient agar), Fungi (Sabouraud), Viruses (tissue culture / embryonated eggs / animal models - NEVER cell-free media). Some bacteria are also obligate intracellular (Rickettsia, Chlamydia) - exceptions.
Sources
- NCERT Class IX Science - Chapter 5: The Fundamental Unit of Life
- NCERT Class XII Biology - Chapter 10: Microbes in Human Welfare