Nokea
Taeniasis is an infection caused by organisms known as:
- A. ringworms
- B. hookworms
- C. tapeworms
- D. pinworms
Correct Answer: C
Rationale: The correct answer is C: tapeworms. Taeniasis is specifically caused by tapeworms of the Taenia species, such as Taenia solium. These parasitic worms infect the intestines of humans through consumption of contaminated food or water. Ringworms (choice A), hookworms (choice B), and pinworms (choice D) are all different types of parasites that cause distinct infections in the body, not taeniasis. Tapeworms are the only organisms among the choices that are directly associated with taeniasis due to their unique life cycle and mode of infection.
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The lysozyme hydrolyzes:
- A. The glycoside bonds between the N-acetylmuramic acid and the N-acetylglucosamine in the peptidoglycan of the cell wall
- B. The phosphate bonds between the carbon atoms in the phospholipids
- C. The disulfide bonds in the immunoglobulin molecule
- D. The hydrogen bonds between the monosaccharides in the bacterial capsules
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).
Bacterial spores are resistant to harsh conditions due to:
- A. their lipid-rich membranes
- B. presence of calcium dipicolinate
- C. rapid metabolism
- D. high water content
Correct Answer: B
Rationale: The correct answer is B because the presence of calcium dipicolinate in bacterial spores helps protect their DNA from damage under harsh conditions. Calcium dipicolinate acts as a stabilizer, preserving the spore structure.
Choice A is incorrect as bacterial spores have a tough protein coat, not a lipid-rich membrane. Choice C is incorrect as bacterial spores have very low metabolic activity. Choice D is incorrect as bacterial spores have low water content to prevent damage during harsh conditions.
Several patients with similar complaints came to the doctor. They all present with weakness, pain in the intestines, indigestion. Feces analysis revealed the need for urgent hospitalization of the patient, who had microbial cysts with four nuclei detected in his samples. Such cysts are characteristic of the following protozoon:
- A. Entamoeba histolytica.
- B. Entamoeba coli.
- C. Balantidium.
- D. Trichomonad.
Correct Answer: A
Rationale: The correct answer is A: Entamoeba histolytica. This protozoon is known to cause amoebic dysentery, presenting symptoms of weakness, intestinal pain, and indigestion. The presence of microbial cysts with four nuclei in fecal samples is characteristic of Entamoeba histolytica. These cysts are the infective form of the parasite and can cause severe invasive disease in the intestines.
Incorrect choices:
B: Entamoeba coli does not typically cause invasive disease or severe symptoms like those described in the question.
C: Balantidium is a ciliated protozoan that causes balantidiasis, which presents differently from the symptoms described in the question.
D: Trichomonad is a flagellated protozoan that typically infects the urogenital tract, not the intestine, and does not form cysts with four nuclei.
In summary, the key clues in the question were the symptoms of weakness, intestinal pain,
A saucer-shaped liquefaction in a gelatin stab is referred to as:
- A. napiform
- B. saccate
- C. crateriform
- D. stratiform
Correct Answer: C
Rationale: The correct answer is C: crateriform. In a gelatin stab, a saucer-shaped liquefaction indicates a depression or crater-like shape. This term accurately describes the appearance of the liquefaction.
A: napiform means turnip-shaped, which is not relevant to the shape in a gelatin stab.
B: saccate means pouch-like, which does not match the saucer-shaped description.
D: stratiform refers to something in layers, which is not applicable to the shape of the liquefaction.
Therefore, C is the most appropriate term to describe the saucer-shaped liquefaction in a gelatin stab.
The bacterial structure that protects against desiccation is:
- A. Capsule
- B. Flagella
- C. Endospore
- D. Pili
Correct Answer: C
Rationale: The correct answer is C: Endospore. Endospores are highly resistant structures formed by certain bacterial species to withstand harsh conditions like desiccation. They contain a tough outer layer that protects the bacterial DNA and other essential components. Capsules (choice A) provide protection against host immune responses but not specifically against desiccation. Flagella (choice B) are used for bacterial motility. Pili (choice D) are involved in bacterial adhesion but do not protect against desiccation. Therefore, endospores are the most suitable choice for protecting against desiccation.