Correct Answer: D

Rationale: The correct answer is D (A and B both). In viral multiplication, the presence of a specific cytopathic effect (CPE) in cell culture indicates viral replication. This is detected visually through changes in cell morphology. Additionally, immunofluorescence detection methods can be used to detect viral antigens within infected cells, confirming viral multiplication. Options C is incorrect as viral colonies are not typically used to detect viral multiplication in cell culture. Option B alone is not sufficient as it only focuses on immunofluorescence detection, while option A alone may not always be specific. Therefore, the combination of A and B provides a more comprehensive and accurate detection method for viral multiplication in cell culture.

Correct Answer: A

Rationale: The correct answer is A: Vibrio cholerae. This bacterium is commonly associated with foodborne illnesses caused by contaminated water due to its ability to survive and multiply in water sources. Vibrio cholerae causes cholera, a severe gastrointestinal infection transmitted through contaminated food and water. Clostridium difficile, Mycobacterium tuberculosis, and Neisseria gonorrhoeae are not typically associated with foodborne illnesses caused by contaminated water. Clostridium difficile causes gastrointestinal infections linked to antibiotic use, Mycobacterium tuberculosis causes tuberculosis through respiratory transmission, and Neisseria gonorrhoeae causes sexually transmitted infections.

Correct Answer: B

Rationale: Step-by-step rationale: 1. Filamentous spiral nucleocapsid is characteristic of Filoviridae, such as Ebola virus. 2. Linear unsegmented single strand (-) RNA is a key feature of Filoviridae genomes. 3. The lipid bilayer membrane of cellular origin is found in Filoviridae viruses. 4. Therefore, the correct answer is B (Filoviridae) due to the alignment of all three morphological features. Summary: - A (Picornaviridae): Has an icosahedral capsid, not filamentous spiral. - C (Orthomyxoviridae): Has a segmented genome, not linear unsegmented. - D (Togaviridae): Has a spherical capsid, not filamentous spiral.

Correct Answer: C

Rationale: The correct answer is C: Identification. Bacteria are studied by identification to determine their specific characteristics and differentiate between different species. Taxonomy (A) is the science of classification, not specific to bacteria. Classification (B) is the process of grouping organisms based on shared characteristics, not specific to bacteria. Nomenclature (D) is the naming system for organisms, not the primary method for studying bacteria. Therefore, identification (C) is the correct choice for studying bacteria.

Correct Answer: D

Rationale: Interferon delta is not a known type of interferon, making choice D incorrect. Interferon beta is indeed produced by fibroblasts (choice A), interferon alpha by leukocytes (choice B), and interferon gamma by lymphocytes (choice C). Each type of interferon is produced by specific cells in the immune system, contributing to the body's defense against viruses and other pathogens.