Nokea
Exotoxins are:
- A. Produced in the microbe cell and then released in the neighbouring...
- B. Produced in the microbe cell and acting into the same cell
- C. Part of the microbe cell and acting into the same cell
- D. Part of the microbe cell, are released outside after cell lysis
Correct Answer: A
Rationale: Exotoxins are proteins produced inside the microbe cell and then released outside the cell to exert their toxic effects on neighboring cells or tissues. This is why choice A is correct. Choices B and C are incorrect because exotoxins are not meant to act within the same cell they are produced in. Choice D is incorrect because exotoxins are usually released without causing cell lysis; they are secreted by the microbe actively rather than being leaked out due to cell damage.
You may also like to solve these questions
A child presented with foul-smelling diarrhea. Stool microscopy revealed trophozoites with two nuclei and flagella. What is the causative agent?
- A. Giardia lamblia
- B. Entamoeba histolytica
- C. Trichomonas vaginalis
- D. Balantidium coli
Correct Answer: A
Rationale: The correct answer is A: Giardia lamblia. Giardia lamblia is a protozoan parasite that causes foul-smelling diarrhea. The trophozoites of Giardia lamblia have two nuclei and flagella, which are characteristic features seen on stool microscopy. The presence of these specific features helps differentiate Giardia lamblia from the other options. Entamoeba histolytica (B) typically presents with one nucleus and lacks flagella. Trichomonas vaginalis (C) is a sexually transmitted parasite with a different morphology. Balantidium coli (D) is a ciliated parasite, not flagellated like Giardia lamblia.
Which bacteria is commonly associated with foodborne illnesses caused by contaminated water?
- A. Vibrio cholerae
- B. Clostridium difficile
- C. Mycobacterium tuberculosis
- D. Neisseria gonorrhoeae
Correct Answer: A
Rationale: The correct answer is A: Vibrio cholerae. This bacterium is commonly associated with foodborne illnesses caused by contaminated water due to its ability to survive and multiply in water sources. Vibrio cholerae causes cholera, a severe gastrointestinal infection transmitted through contaminated food and water. Clostridium difficile, Mycobacterium tuberculosis, and Neisseria gonorrhoeae are not typically associated with foodborne illnesses caused by contaminated water. Clostridium difficile causes gastrointestinal infections linked to antibiotic use, Mycobacterium tuberculosis causes tuberculosis through respiratory transmission, and Neisseria gonorrhoeae causes sexually transmitted infections.
A Gram-negative bacterium producing a blue-green pigment and having a fruity odor was isolated from a patient's wound infection. What is the likely causative agent?
- A. Pseudomonas aeruginosa
- B. Escherichia coli
- C. Klebsiella pneumoniae
- D. Proteus mirabilis
Correct Answer: A
Rationale: Step-by-step rationale:
1. Blue-green pigment + fruity odor are characteristic of Pseudomonas aeruginosa.
2. P. aeruginosa is a Gram-negative bacterium commonly associated with wound infections.
3. P. aeruginosa is known for its ability to produce pyocyanin (blue-green pigment) and a sweet, fruity odor.
4. Other choices like E. coli, K. pneumoniae, and P. mirabilis do not typically produce blue-green pigment or fruity odor.
5. Therefore, based on the characteristics observed, the likely causative agent is Pseudomonas aeruginosa.
Summary of other choices:
- Escherichia coli: Does not produce blue-green pigment or fruity odor.
- Klebsiella pneumoniae: Does not typically produce blue-green pigment or fruity odor.
- Proteus mirabilis: Does not produce blue-green pigment or fruity odor.
Compared to primary immune response the secondary immune response
- A. 1. Is quicker
- B. 2. Produces much more antibodies
- C. 3. Requires more antigen stimulations
- D. 4. Is slower
Correct Answer: A
Rationale: The correct answer is A because the secondary immune response is quicker due to memory B and T cells being already present from the primary response. These memory cells can quickly recognize and respond to the antigen upon re-exposure, leading to a faster and more efficient immune response. Choices B and C are incorrect as the secondary response produces more antibodies and requires fewer antigen stimulations. Choice D is also incorrect as the secondary response is faster than the primary response.
Toxoplasma gondii belongs to which group of eukaryotic organisms?
- A. Algae
- B. Fungi
- C. Protozoans
- D. Helminths
Correct Answer: C
Rationale: Toxoplasma gondii is a protozoan parasite known to cause toxoplasmosis. It belongs to the group of eukaryotic organisms called protozoans because it is a single-celled organism with complex cellular structures. Protozoans are characterized by their ability to move and perform essential functions independently. Algae (choice A) are photosynthetic eukaryotic organisms, fungi (choice B) are non-photosynthetic eukaryotes that include molds and yeasts, and helminths (choice D) are multicellular parasitic worms. Therefore, the correct answer is C because Toxoplasma gondii is a protozoan parasite.