Correct Answer: A

Rationale: The correct answer is A: protein envelope around the nucleic acid. Viral capsid is the protein coat that surrounds and protects the viral nucleic acid (DNA or RNA). This structure helps in protecting the genetic material from degradation and facilitates the attachment of the virus to host cells. Option B is incorrect as it suggests the nucleic acid is coated with protein, which is not the case. Option C is incorrect as not all viruses have an outer membrane. Option D is incorrect as viruses typically do not have a lipoprotein membrane.

Correct Answer: A

Rationale: The most probable diagnosis is Tetanus (Choice A) based on the symptoms described. Tetanus is characterized by muscle stiffness, difficulty opening the mouth (trismus), muscle spasms, and convulsions. The progression of symptoms from muscle tension to generalized convulsions every 10-15 min is classic for tetanus. Tetania (Choice B) is similar but typically presents with more subtle muscle contractions rather than convulsions. Meningoencephalitis (Choice C) presents with fever, headache, and altered mental status, not the muscle symptoms described. Hemorrhagic stroke (Choice D) presents with sudden onset neurological deficits like weakness or sensory changes, not the muscle symptoms described.

Correct Answer: B

Rationale: The correct answer is B: Conjugation. Conjugation involves the transfer of genetic material from a donor cell to a recipient cell through direct cell-to-cell contact, typically mediated by a conjugative plasmid. During conjugation, a conjugative pilus forms a bridge between the donor and recipient cells, allowing the transfer of genetic material. A: Replication is the process of copying DNA to produce two identical DNA molecules. It does not involve the transfer of genetic material between cells. C: Transformation is the uptake and incorporation of foreign DNA from the environment by a bacterial cell. It does not require direct cell-to-cell contact. D: Transduction is the transfer of genetic material from one bacterium to another by a bacteriophage vector. It does not involve direct cell-to-cell contact between the donor and recipient cells.

Correct Answer: D

Rationale: The correct answer is D: Mesosomes. Mesosomes are infoldings of the prokaryotic cytoplasmic membrane that play a role in cell division and respiration. This structure is not found in eukaryotic cells. Cristae (A) are infoldings of the mitochondrial inner membrane in eukaryotic cells. Granum (B) refers to stacks of thylakoid membranes in chloroplasts. Flagella (C) are whip-like structures used for movement and are not related to cytoplasmic membrane invaginations. Therefore, the correct answer is D as mesosomes are unique to prokaryotic cells and are involved in various cellular processes.

Correct Answer: C

Rationale: The correct answer is C: Escherichia coli. E.coli is the most common urinary tract pathogen due to its ability to adhere to and infect the urinary tract epithelium. It accounts for approximately 80-85% of urinary tract infections. It possesses specific virulence factors that enable it to colonize and cause infection in the urinary tract. Proteus mirabilis (A) is known for causing complicated UTIs, but it is less common than E.coli. Staphylococcus aureus (B) is not a common urinary pathogen. Pseudomonas aeruginosa (D) is more commonly associated with hospital-acquired infections, rather than community-acquired urinary tract infections.