SM Microbial Identification & Classification — Questions and Answers
Question 1: Which staining technique is commonly used to differentiate bacterial species?
- Acid-fast stain
- Gram stain (Correct answer)
- Endospore stain
- Negative stain
Correct answer: Gram stain
The Gram stain differentiates bacteria based on the structure of their cell walls, classifying them as Gram-positive or Gram-negative.
Question 2: What is the primary difference between prokaryotic and eukaryotic microorganisms?
- Presence of ribosomes
- Absence of a nucleus in prokaryotes (Correct answer)
- Type of DNA they contain
- Size of the cell
Correct answer: Absence of a nucleus in prokaryotes
Prokaryotic cells, such as bacteria, lack a nucleus, whereas eukaryotic cells, such as fungi and protozoa, have a defined nucleus.
Question 3: Which molecular technique is commonly used for bacterial identification?
- ELISA
- PCR (Correct answer)
- Spectrophotometry
- Western blot
Correct answer: PCR
Polymerase Chain Reaction (PCR) amplifies specific DNA sequences, allowing for rapid and accurate bacterial identification.
Question 4: Which type of bacteria lacks a cell wall?
- Staphylococcus
- Mycoplasma (Correct answer)
- Clostridium
- Bacillus
Correct answer: Mycoplasma
Mycoplasma species lack a cell wall, making them resistant to antibiotics that target cell wall synthesis, such as beta-lactams.
Question 5: Which classification system is commonly used to identify microorganisms?
- Linnean classification
- Bergey’s Manual (Correct answer)
- Binomial nomenclature
- Koch’s postulates
Correct answer: Bergey’s Manual
The Bergey’s Manual of Systematic Bacteriology is widely used for classifying and identifying bacterial species based on morphological, biochemical, and genetic characteristics.
Question 6: What is the main characteristic of facultative anaerobes?
- Require oxygen to grow
- Can survive with or without oxygen (Correct answer)
- Are killed by oxygen
- Only ferment sugars
Correct answer: Can survive with or without oxygen
Facultative anaerobes can survive in both aerobic and anaerobic environments, switching between aerobic respiration and fermentation as needed.
SM Microbial Identification & Classification
Which staining technique is commonly used to differentiate bacterial species?