Which type of RNA carries the genetic code for protein synthesis?

Correct Answer: A

Rationale: The correct answer is A: mRNA. mRNA carries the genetic code from the DNA in the cell nucleus to the ribosomes in the cytoplasm, where protein synthesis occurs. It serves as a template for protein synthesis by specifying the order of amino acids. tRNA (choice B) brings amino acids to the ribosome during protein synthesis. rRNA (choice C) is a structural component of ribosomes. snRNA (choice D) is involved in RNA processing and splicing, not protein synthesis. Therefore, choice A is correct as it directly carries the genetic code for protein synthesis.

Correct Answer: A

Rationale: The correct answer is A: Nucleus. DNA viruses replicate in the host cell's nucleus because they require access to the host cell's DNA replication machinery. The nucleus contains the necessary enzymes and factors for DNA replication to occur accurately. The DNA viruses need to utilize these host cell components to replicate their own genetic material. Summary of why other choices are incorrect: B: Cytoplasm - Cytoplasm lacks the necessary enzymes and machinery for accurate DNA replication. C: Endoplasmic Reticulum - ER is involved in protein synthesis and processing, not DNA replication. D: Golgi Apparatus - Golgi apparatus is responsible for processing and packaging proteins, not DNA replication.

Correct Answer: A

Rationale: The correct answer is A: Itraconazole. Itraconazole is an antifungal medication commonly used to treat candidosis. It works by inhibiting the synthesis of ergosterol, a key component of fungal cell membranes. This action disrupts the integrity of the fungal cell membrane, leading to cell death. Griseofulvin (B) is primarily used to treat fungal infections of the skin and nails, not mucous membranes. Nitrofungin (C) is not commonly used for candidosis treatment. Amphotericin (D) is a potent antifungal medication but is typically reserved for severe or systemic fungal infections due to its potential side effects.

Correct Answer: B

Rationale: The correct answer is B: Flagella. Flagella are whip-like appendages used by bacteria for movement. They rotate in a corkscrew motion to propel the bacteria through their environment. Pili (choice A) are hair-like structures used for attachment, not movement. Capsules (choice C) are protective layers around bacteria, not involved in movement. Fimbriae (choice D) are also used for attachment and biofilm formation, not for movement. Therefore, the correct choice is B as flagella are specifically adapted for bacterial motility.

Correct Answer: A

Rationale: The correct answer is A: Clostridium botulinum and Clostridium tetani. Both bacteria produce exotoxins that affect the nervous system. Clostridium botulinum produces botulinum toxin, causing botulism, leading to muscle paralysis. Clostridium tetani produces tetanospasmin, causing tetanus, leading to muscle stiffness and spasms. Choice B (Escherichia coli and Salmonella) are known for causing gastrointestinal infections, not specifically affecting the nervous system. Choice C (Bacillus anthracis and Listeria monocytogenes) produce toxins that primarily affect other body systems, not the nervous system. Choice D (Pseudomonas aeruginosa and Staphylococcus aureus) are associated with skin and respiratory infections, not neurological effects.

Correct Answer: B

Rationale: The correct answer is B: Neisseria gonorrhoeae. This bacterium is responsible for causing gonorrhea. Neisseria gonorrhoeae is a sexually transmitted bacterium that infects the mucous membranes of the reproductive tract. It is known for causing symptoms such as painful urination and discharge. Chlamydia trachomatis (choice A) is another sexually transmitted bacterium but is not responsible for gonorrhea. Treponema pallidum (choice C) causes syphilis, not gonorrhea. Escherichia coli (choice D) is a common bacterium found in the gut and is not associated with causing gonorrhea. Therefore, Neisseria gonorrhoeae is the correct answer for this question.

Correct Answer: C

Rationale: The correct answer is C: Bacillus anthracoides. 1. The patient's symptoms align with cutaneous anthrax, caused by Bacillus anthracis. 2. Presence of immobile streptobacilli able of capsulation matches the characteristics of Bacillus anthracis. 3. Symptoms such as black crust, peripheral vesicular rash, and non-painful edema are classic for cutaneous anthrax. 4. Choice A: Bacillus antracis is a misspelling, not a valid option. 5. Choice B: Staphylococcus aureus does not match the symptoms described in the scenario. 6. Choice D: Bacillus megaterium is not associated with cutaneous anthrax.

Correct Answer: A

Rationale: Ribosomes are responsible for protein synthesis, where they translate the genetic information from mRNA into specific amino acid sequences to form proteins. This process occurs in both prokaryotic and eukaryotic cells. Ribosomes do not participate in the breakdown of substances, which is mainly carried out by lysosomes or proteasomes. Oxidative phosphorylation involves the generation of ATP in mitochondria, not ribosomes. Ribosomes do not inactivate antibiotics; this is typically done by enzymes or chemical modifications. Therefore, the correct answer is A as ribosomes play a crucial role in protein synthesis.

Correct Answer: D

Rationale: The correct answer is D: simple diffusion. In simple diffusion, molecules move from an area of high concentration to low concentration without the need for energy input. Hydrostatic pressure is a form of passive transport that drives molecules to equalize concentration. Filtration (A) involves the movement of solutes through a membrane under pressure. Exocytosis (B) is the process by which cells release substances outside the cell using energy. Osmosis (C) is the movement of water molecules across a selectively permeable membrane. Therefore, simple diffusion is the most appropriate choice in this scenario.