A sputum smear from a patient with pneumonia revealed Gram-positive diplococci with pointed ends surrounded by capsules. What microorganism is most likely?

Correct Answer: A

Rationale: Step-by-step rationale: 1. Gram-positive diplococci with pointed ends indicate Streptococcus pneumoniae. 2. Presence of capsules supports the likelihood of S. pneumoniae. 3. S. pneumoniae is a common cause of pneumonia. 4. Klebsiella pneumoniae is Gram-negative and does not form diplococci. 5. Neisseria meningitidis typically causes meningitis, not pneumonia. 6. Staphylococcus aureus is Gram-positive but does not typically present as diplococci in pneumonia cases.

Correct Answer: C

Rationale: The correct answer is C: nucleotides. Nucleotides are the structural units of nucleic acids, consisting of a nitrogenous base, a sugar molecule, and a phosphate group. The nitrogenous base can be adenine, thymine, cytosine, guanine, or uracil. Histones (B) are proteins that DNA wraps around in chromosomes, not structural units of nucleic acids. Nucleosides (A) are composed of a nitrogenous base and a sugar molecule but lack the phosphate group present in nucleotides. N-bases (D) is not a recognized term in biology and does not accurately describe the structural units of nucleic acids.

Correct Answer: A

Rationale: The correct answer is A: 1 chromosome. Bacterial cells typically have a singular circular chromosome that contains their genetic material. This chromosome is essential for the cell's survival and contains all the necessary genetic information for its functions. Choices B, C, and D are incorrect because they refer to the chromosome numbers found in human cells (23 pairs or 46 individual chromosomes). Bacteria, being prokaryotic organisms, have a simpler genetic makeup compared to eukaryotic organisms like humans, hence they possess only one chromosome.

Correct Answer: B

Rationale: The correct answer is B: serratia spp. This is because serratia spp. are not typically found in the normal skin microflora. Normal skin microflora primarily consist of bacteria such as diphtheroids, alpha-hemolytic streptococci, and epidermidis. Serratia spp. are more commonly associated with healthcare-associated infections rather than being a part of the skin's natural bacterial flora. Therefore, choice B is the correct answer. Choices A, C, and D are incorrect as they are commonly found in the normal skin microflora.

Correct Answer: A

Rationale: The correct answer is A: ocular lens. The ocular lens is the lens closest to the eye in a compound light microscope. This lens is responsible for magnifying the image produced by the objective lens. It typically has a magnification power of 10x. The objective lens, choice B, is positioned closer to the specimen and provides the primary magnification of the image. The condenser, choice C, is located beneath the stage and helps focus light onto the specimen. The stage, choice D, is where the specimen is placed for observation. Therefore, the ocular lens is the correct choice as it is the lens closest to the eye and responsible for further magnifying the image.