Amino acids are building blocks of

Correct Answer: D

Rationale: The correct answer is D: Proteins. Amino acids are the building blocks of proteins because they are linked together in a specific sequence to form protein chains. Proteins are essential for various biological functions in the body. Incorrect options: A: Carbohydrates - Carbohydrates are made up of sugar molecules, not amino acids. B: Nucleic acids - Nucleic acids, like DNA and RNA, are made up of nucleotides, not amino acids. C: Lipids - Lipids are composed of fatty acids and glycerol, not amino acids.

Correct Answer: A

Rationale: The correct answer is A: ELISA test. The ELISA test is typically the initial screening test for HIV due to its high sensitivity in detecting HIV antibodies. It is cost-effective and quick. Western blot test is a confirmatory test used if ELISA is positive. Viral load studies monitor the progression of the disease but are not typically done first. Rheumatoid factor test is unrelated to HIV testing. Therefore, the ELISA test is the most appropriate initial step in HIV testing.

Correct Answer: B

Rationale: The correct answer is B: thylakoid membranes within chloroplasts. Prokaryotic cells lack membrane-bound organelles like chloroplasts, where thylakoid membranes are found. This is a key feature of prokaryotic cells. Choices A, C, and D are characteristics that can occur in prokaryotic cells. Cellular organization is present in prokaryotic cells, oxygenic photosynthesis can be carried out by some prokaryotic organisms, and prokaryotic cells can perform anaerobic respiration.

Correct Answer: B

Rationale: The correct answer is B: more enveloped forms. This trend can be explained by the complexity of host organisms. Bacteria have simple cell structures, making enveloped viruses less common. As we move from bacteria to plants and vertebrate animals, the complexity of host cells increases, leading to a higher prevalence of enveloped viruses. This trend is due to the need for enveloped viruses to evade the host's immune system and facilitate entry into host cells. Choices A, C, and D are incorrect because they do not consider the relationship between virus structure and host complexity.

Correct Answer: B

Rationale: The correct answer is B: propionic acid, carbon dioxide. Propionic acid is produced by bacteria in Swiss cheese, contributing to its nutty flavor. The bacteria also produce carbon dioxide, which forms the characteristic holes. Lactate (A) is a byproduct of bacteria in cheese but not responsible for the flavor or holes. Acetic acid (C) is not commonly found in Swiss cheese. Ethanol (D) and hydrogen are not involved in the flavor or hole formation.