Biology multiple-choice questions related to microorganisms along with their answers

1. Which of the following is a characteristic of prokaryotic cells?
   A) Membrane-bound organelles 
   B) Nucleus 
   C) Circular DNA 
   D) Multicellular organization 

Answer: C - Circular DNA

2. What is the primary role of bacteria in the nitrogen cycle?
   A) Nitrogen fixation 
   B) Photosynthesis 
   C) Decomposition 
   D) Respiration 

Answer: A - Nitrogen fixation

3. Which of the following microorganisms is used in the production of yogurt?
   A) Saccharomyces cerevisiae 
   B) Lactobacillus bulgaricus 
   C) Escherichia coli 
   D) Streptococcus pneumoniae 

Answer: B - Lactobacillus bulgaricus

4. Antibiotics are effective against which type of organism?
   A) Viruses 
   B) Fungi 
   C) Bacteria 
   D) All of the above

Answer: C - Bacteria

5. Which structure is found in viruses but not in bacteria?
   A) Cell wall 
   B) RNA or DNA 
   C) Plasma membrane 
   D) Ribosomes 

Answer: B - RNA or DNA

6. What process do yeast cells primarily undergo to produce energy under anaerobic conditions?
   A) Fermentation 
   B) Aerobic respiration 
   C) Photosynthesis 
   D) Chemosynthesis 

Answer: A - Fermentation

7. Which of the following diseases is caused by a virus?
   A) Tuberculosis 
   B) Malaria 
   C) Influenza 
   D) Fungal infections 

Answer: C - Influenza

8. Which microorganism is known for its role in bioremediation?
   A) Lactobacillus 
   B) Pseudomonas 
   C) Penicillium 
   D) Saccharomyces 

Answer: B - Pseudomonas

9. The Gram stain is used to differentiate bacteria based on what characteristic?
   A) Shape 
   B) Size 
   C) Cell wall composition 
   D) Metabolic activity 

Answer: C - Cell wall composition

10. Which of the following is a beneficial effect of microorganisms?
    A) Causing disease 
    B) Decomposing organic matter 
    C) Producing toxins 
    D) Contaminating food 

Answer: B - Decomposing organic matter

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