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Portage Learning: Microbiology,
Module 3 Questions and Answers | Latest Version | 2025/2026 | Correct & Verified
What type of cell wall structure is found in Gram-positive bacteria?✔✔ Thick peptidoglycan layer
What color does a Gram-positive bacterium appear after Gram staining?✔✔ Purple
What color does a Gram-negative bacterium appear after Gram staining?✔✔ Pink
What component of the Gram-negative cell wall can act as an endotoxin?✔✔ Lipopolysaccharide (LPS)
What is the purpose of the iodine step in the Gram stain procedure?✔✔ Acts as a mordant to fix the crystal violet 1 / 3
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What is the function of alcohol in the Gram staining process?✔✔ Decolorizes Gram-negative cells
What type of microscope is typically used to view stained bacteria?✔✔ Light microscope
What structure is used by bacteria for movement?✔✔ Flagella
What structure allows bacteria to attach to surfaces?✔✔ Fimbriae
What structure helps bacteria exchange genetic material?✔✔ Pilus
What type of staining technique is used to identify Mycobacterium species?✔✔ Acid-fast stain 2 / 3
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What substance in the cell wall makes Mycobacterium acid-fast?✔✔ Mycolic acid
What type of bacteria do not retain the Gram stain due to lack of a cell wall?✔✔ Mycoplasma
What is the role of the capsule in bacterial cells?✔✔ Protects against phagocytosis
What is the function of the bacterial cell wall?✔✔ Provides shape and structural support
What type of cell wall do archaea possess?✔✔ Pseudopeptidoglycan or protein-based wall
What organelle do prokaryotes lack that eukaryotes have?✔✔ Nucleus
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