Which bacteria is responsible for causing botulism?

Correct Answer: A

Rationale: The correct answer is A: Clostridium botulinum. This bacterium is responsible for causing botulism due to its production of botulinum toxin, which is one of the most potent neurotoxins known. Clostridium botulinum thrives in anaerobic conditions like improperly canned foods. Staphylococcus aureus (B), Bacillus anthracis (C), and Pseudomonas aeruginosa (D) do not produce the botulinum toxin and are not associated with botulism. Staphylococcus aureus is known for causing food poisoning, Bacillus anthracis for anthrax, and Pseudomonas aeruginosa for various infections, but not botulism.

Correct Answer: A

Rationale: The correct answer is A: The lysozyme hydrolyzes the glycoside bonds between the N-acetylmuramic acid and the N-acetylglucosamine in the peptidoglycan of the cell wall. This is because lysozyme is an enzyme that specifically targets the peptidoglycan layer of bacterial cell walls, breaking down the structure by cleaving the glycosidic bonds between these two specific sugar molecules. This action weakens the cell wall, leading to bacterial cell lysis. The other choices are incorrect because lysozyme does not target phosphate bonds in phospholipids (B), disulfide bonds in immunoglobulins (C), or hydrogen bonds in bacterial capsules (D).

Correct Answer: A

Rationale: The correct answer is A: chloroplasts. Algae and plant cells have chloroplasts, which are responsible for photosynthesis. This organelle contains chlorophyll, enabling these cells to convert sunlight into energy. Mitochondria (B) are found in all eukaryotic cells, not specific to algae and plants. Vacuoles (C) are present in plant cells but also in other eukaryotic cells. Vesicles (D) are membrane-bound sacs found in all types of cells for transport and storage purposes, not unique to algae and plants. Therefore, A is the correct answer.

Correct Answer: A

Rationale: The Burri-Gins staining technique is used to identify the presence of capsules around bacteria. Capsules are protective structures that some bacteria produce to evade the immune system. This technique stains the capsule, making it visible under a microscope. Therefore, the correct answer is A: Capsule formation. Incorrect: B: Spore formation - Spores are not typically identified using the Burri-Gins staining technique. C: Acid resistance - This property is not specifically identified by Burri-Gins staining. D: Alkali resistance - This property is not specifically identified by Burri-Gins staining.

Correct Answer: B

Rationale: The correct answer is B: Neisseria gonorrhoeae. This bacterium is known to cause gonorrhea, a sexually transmitted infection. Neisseria gonorrhoeae specifically infects the mucous membranes of the reproductive tract in both men and women. It is transmitted through sexual contact. Explanation of other choices: A: Chlamydia trachomatis is a bacterium that causes chlamydia, not gonorrhea. C: Mycoplasma genitalium is associated with non-gonococcal urethritis, not gonorrhea. D: Treponema pallidum is the bacterium that causes syphilis, not gonorrhea. Therefore, Neisseria gonorrhoeae is the correct answer based on its direct association with causing gonorrhea.

Correct Answer: A

Rationale: The correct answer is A: Bacterial ribosomes synthesize proteins. Ribosomes are cellular organelles responsible for protein synthesis by translating mRNA into amino acids. They are essential for the production of proteins needed for cell function. Choices B, C, and D are incorrect because ribosomes do not synthesize DNA, degrade toxic substances, or assist in cell division. DNA synthesis is carried out by DNA polymerase, degradation of toxic substances is typically done by enzymes, and cell division is primarily regulated by the cell cycle machinery.

Correct Answer: D

Rationale: The correct answer is D: Chlamydia trachomatis. Lymphogranuloma venereum (LGV) is caused by Chlamydia trachomatis serovars L1, L2, and L3. These serovars infect the lymphatic system leading to swelling and inflammation. Choice A, Chlamydia pneumoniae, is associated with respiratory infections, not LGV. Choice B, Chlamydia psittaci, causes psittacosis in birds and humans. Choice C, Mycoplasma genitalium, is a separate STI but is not the causative agent for LGV. The key to the correct answer is understanding the specific pathogen responsible for LGV based on its clinical presentation and mode of transmission.

Correct Answer: B

Rationale: The correct answer is B: Sporadic disease. When an infection occurs in several persons without any epidemiological link, it is considered sporadic. This term is used to describe isolated cases that do not form a specific pattern or cluster. It indicates random occurrences and lack of connection between the affected individuals. A: Epidemic refers to a sudden increase in the number of cases of a disease within a specific population or region, usually linked by a common source or exposure. C: Endemic signifies the constant presence of a disease within a specific population or region, with cases occurring at a relatively stable rate. D: Pandemic indicates a global outbreak of a disease affecting a large number of people across multiple countries or continents.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Metronidazole is a synthetic antiprotozoal drug commonly used for wound infection prevention. 2. It is highly effective against Helicobacter pylori, a bacterium that causes stomach ulcers. 3. Metronidazole works by disrupting DNA structure in bacteria, leading to their death. 4. Chingamin (Chloroquine) is an antimalarial drug, not effective against Helicobacter pylori. 5. Doxycycline hydrochloride is an antibiotic used for bacterial infections, not specifically for H. pylori. 6. Aciclovir is an antiviral drug used for herpes infections, not effective against H. pylori. Summary: Metronidazole is the correct answer as it is specifically effective against H. pylori and commonly used for wound infection prevention. Other choices are incorrect as they target different types of infections.