Nokea
The type of antibody that can cross the placenta is:
- A. IgA
- B. IgM
- C. IgG
- D. IgD
Correct Answer: C
Rationale: The correct answer is C: IgG. IgG is the only antibody that can cross the placenta due to its small size and unique structure, allowing it to provide passive immunity to the fetus. IgA is mainly found in mucosal secretions, IgM is too large to cross the placental barrier, and IgD plays a role in B cell activation but is not involved in placental transfer.
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When doctors of a sanitary and epidemiologic institution examine employees of public catering establishments they often reveal asymptomatic parasitosis, that is when a healthy person is a carrier of cysts that infect other people. What causative agent can parasitize in such a way?
- A. Dysenteric amoeba
- B. Malarial plasmodium
- C. Enteral trichomonad
- D. Dermatotropic leishmania
Correct Answer: A
Rationale: The correct answer is A: Dysenteric amoeba. This is because dysenteric amoebas can cause asymptomatic parasitosis, where a healthy person carries cysts that can infect others. Dysenteric amoebas are known to infect the intestines and can be transmitted through contaminated food or water.
Choice B, Malarial plasmodium, causes malaria transmitted through mosquitoes. Choice C, Enteral trichomonad, causes diarrhea and is transmitted through contaminated water. Choice D, Dermatotropic leishmania, causes skin lesions and is transmitted through sandfly bites. These choices do not fit the scenario of asymptomatic parasitosis in public catering establishments.
A group of Ukrainian tourists returning from Samarqand was bringing with them gerbils. During examination in customs office ulcers were detected on the skin of the animals. What protozoa is the most likely to cause the disease in the animals, if mosquitoes are the carriers?
- A. Leishmania tropica major
- B. Balantidium coli
- C. P. falciparum
- D. T. cruzi
Correct Answer: C
Rationale: Rationale:
1. The presence of ulcers in animals suggests a parasitic infection.
2. Mosquitoes as carriers indicate a protozoan transmitted through insect bites.
3. Among the choices, Plasmodium falciparum causes malaria transmitted by mosquitoes.
4. Leishmania tropica major causes cutaneous leishmaniasis, not ulcers.
5. Balantidium coli causes intestinal infections, not skin ulcers.
6. Trypanosoma cruzi causes Chagas disease, not skin ulcers.
Peptidoglycan is typically found in the:
- A. cell wall
- B. plasma membrane
- C. nucleus
- D. endoplasmic reticulum
Correct Answer: A
Rationale: Peptidoglycan is a major component of bacterial cell walls, providing structural support and protection. The correct answer is A because peptidoglycan is typically found in the cell wall of bacteria. The cell wall is crucial for maintaining the shape of the bacterial cell and protecting it from external stresses. The plasma membrane (choice B) is primarily composed of phospholipids and proteins, not peptidoglycan. The nucleus (choice C) is found in eukaryotic cells and contains genetic material, not peptidoglycan. The endoplasmic reticulum (choice D) is an organelle involved in protein synthesis and lipid metabolism, but it does not contain peptidoglycan. Therefore, the correct answer is A as peptidoglycan is typically found in the cell wall of bacteria.
Which of the following bacteria is known for producing a capsule that helps it avoid the immune system?
- A. Streptococcus pneumoniae
- B. Escherichia coli
- C. Salmonella enterica
- D. Bacillus subtilis
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pneumoniae. This bacterium is known for producing a capsule that helps it evade the immune system. The capsule acts as a protective barrier, making it difficult for the immune system to recognize and attack the bacteria. Streptococcus pneumoniae is a common cause of pneumonia and meningitis.
Explanation for why other choices are incorrect:
B: Escherichia coli does not typically produce a capsule for immune evasion. It is more commonly associated with gastrointestinal infections.
C: Salmonella enterica also does not produce a capsule for immune evasion. It is known for causing foodborne illness.
D: Bacillus subtilis is a soil bacterium that is not known for producing a capsule to avoid the immune system.
The dynamic balance of the species in the normal microflora is known as
- A. dysbiosis
- B. eukaryota
- C. dispersion
- D. eubiosis
Correct Answer: D
Rationale: The correct answer is D: eubiosis. Eubiosis refers to a state of balance and harmony among the species in the normal microflora. This term signifies a healthy and stable microbial community. Dysbiosis (A) is the opposite, indicating an imbalance or disruption in the microflora. Eukaryota (B) refers to organisms with cells containing a nucleus, not specifically related to the balance of microflora. Dispersion (C) refers to the spreading or distribution of microorganisms, not specifically related to their balance. In summary, eubiosis best describes the dynamic balance of species in the normal microflora, making it the correct choice.