analyse_media
Here are the answers to all 10 MCQs from your B.Sc.(N) 3rd Semester - Applied Microbiology exam paper:
Q1. Multiple Choice Questions - Answers
(i) The bacterial cells are at their metabolic peak during:
- B. Log phase ✓
- During the log (exponential) phase, bacteria are actively dividing, metabolically most active, and at peak growth rate.
(ii) Identify the obligate anaerobes:
- C. Cl. tetani ✓
- Clostridium tetani is a strict/obligate anaerobe. Salmonella and Vibrio cholerae are facultative anaerobes; S. aureus is also facultative.
(iii) Gram negative bacteria appear as:
- A. Pink ✓
- Gram-negative bacteria lose the crystal violet stain and take up the safranin counterstain, appearing pink/red.
(iv) Bacteria multiply by:
- B. Simple binary fission ✓
- Binary fission is the primary mode of asexual reproduction in bacteria - the cell splits into two identical daughter cells.
(v) Blood agar medium is:
- B. Enriched medium ✓
- Blood agar is an enriched medium (nutrient-rich base supplemented with blood to support fastidious organisms). It can also show differential properties (hemolysis patterns), but "enriched" is the primary classification.
(vi) Example for DNA virus:
- B. Adeno virus ✓
- Adenovirus is a dsDNA virus. HIV is a retrovirus (RNA), Rabies is an RNA virus, Zika is an RNA virus.
(vii) Plasma cells are the end cells of:
- B. B-cells ✓
- Plasma cells are terminally differentiated B lymphocytes that secrete antibodies (immunoglobulins).
(viii) Mycobacterium tuberculosis was first discovered by:
- A. Robert Koch ✓
- Robert Koch identified and cultured M. tuberculosis in 1882. This is why TB is sometimes called "Koch's disease."
(ix) Wilson and Blair medium is used for isolation of:
- B. Salmonella Typhi ✓
- Wilson and Blair medium (bismuth sulphite agar) is a selective medium specifically used to isolate Salmonella Typhi, which produces black metallic sheen colonies on it.
(x) Compound microscope was discovered by:
- C. Johnsen & Hans ✓ (Zacharias Janssen and his father Hans Janssen)
- The compound microscope is credited to Zacharias Janssen (and his father Hans) around 1590. Leeuwenhoek later improved the single-lens microscope and is known as the "father of microbiology."
Score summary: All 10 questions have clear single best answers as marked above. Let me know if you want explanations on any specific question in more detail!
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