1. Which biochemical assay would be used to determine the presence of catalase enzyme in bacteria? A) Coagulase test B) Oxidase test C) Catalase test D) Urease test Answer: C) Catalase test Rationale: The catalase test is used to identify organisms that produce the enzyme catalase, which breaks down hydrogen peroxide into water and oxygen, evident by the release of oxygen bubbles. 2. In a biochemical assay for urease activity, what color change is indicative of a positive result? A) Red to yellow B) Yellow to red C) Colorless to pink D) Pink to colorless Answer: C) Colorless to pink Rationale: Urease activity is indicated by the hydrolysis of urea, resulting in an alkaline end product that changes the color of the medium from colorless to pink. 3. What is the purpose of the indole test in microbiology? A) To detect the ability to ferment lactose B) To identify bacteria capable of producing indole from tryptophan C) To determine the presence of citrate-utilizing bacteria D) To assess the ability to produce hydrogen sulfide Answer: B) To identify bacteria capable of producing indole from tryptophan Rationale: The indole test is used to determine if an organism can produce the compound indole from the amino acid tryptophan, which is a characteristic of certain bacterial species. 4. Which assay would you perform to assess the ability of a microorganism to ferment mannitol? A) Methyl red test B) Voges-Proskauer test