Nokea
What type of immune reaction is most common in identification of vibrio cholerae
- A. Agglutination
- B. Precipitation
- C. Western blot
- D. ELISA
Correct Answer: A
Rationale: The correct answer is A: Agglutination. Agglutination is commonly used to identify Vibrio cholerae by clumping together the bacteria with specific antibodies. This reaction occurs when antibodies bind to antigens on the bacterial surface, leading to visible clumps. In contrast, Precipitation, Western blot, and ELISA are not typically used to identify Vibrio cholerae. Precipitation involves antigen-antibody complexes becoming insoluble, Western blot is used for protein detection, and ELISA is commonly used for detecting specific antigens or antibodies in a sample. Agglutination is the most appropriate choice for identifying Vibrio cholerae due to its specific interaction with the bacteria's surface antigens.
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Which of the following bacteria is associated with the disease known as whooping cough?
- A. Bordetella pertussis
- B. Clostridium tetani
- C. Haemophilus influenzae
- D. Staphylococcus aureus
Correct Answer: A
Rationale: 1. Bordetella pertussis causes whooping cough.
2. It secretes toxins that damage the respiratory tract.
3. Symptoms include severe coughing fits and the characteristic "whoop" sound.
4. Clostridium tetani causes tetanus, not whooping cough.
5. Haemophilus influenzae causes various infections, not whooping cough.
6. Staphylococcus aureus causes skin infections, not whooping cough.
Examination of duodenal contents revealed some pyriform protozoa with twin nuclei and four pairs of flagella. There were two supporting filaments between the nuclei and a suctorial disc on the ventral side. What representative of protozoa was revealed in this patient?
- A. Lamblia
- B. Toxoplasma
- C. Leishmania
- D. Intestinal trichomonad
Correct Answer: A
Rationale: Rationale for Correct Answer A (Lamblia):
1. Pyriform protozoa with twin nuclei, four pairs of flagella, and a suctorial disc match the characteristics of Giardia lamblia.
2. The presence of two supporting filaments between the nuclei is a unique feature of Giardia lamblia.
3. Giardia lamblia is known to infect the duodenum and cause symptoms such as diarrhea and abdominal pain.
Summary of Incorrect Choices:
B: Toxoplasma - Toxoplasma gondii is not characterized by four pairs of flagella or supporting filaments in the nuclei.
C: Leishmania - Leishmania species do not typically have the described morphology or location in the duodenum.
D: Intestinal trichomonad - Intestinal trichomonads do not exhibit the specific features mentioned in the question, such as twin nuclei and supporting filaments.
Which of the following characteristics of mumps infection is NOT true:
- A. Only the person can be infected
- B. Is a vaccine-preventable disease
- C. Is a highly contagious disease
- D. Transmission routes are via air droplets and direct contact
Correct Answer: A
Rationale: Step-by-step rationale:
1. Mumps is a contagious disease transmitted through air droplets and direct contact.
2. The correct answer is A because mumps can infect both humans and animals.
3. Choice B is incorrect as mumps is vaccine-preventable.
4. Choice C is correct as mumps is highly contagious.
5. Choice D is accurate as mumps is transmitted via air droplets and direct contact.
Summary:
The correct answer is A because mumps can infect both humans and animals, making it untrue that only humans can be infected. Choices B, C, and D are incorrect as mumps is vaccine-preventable, highly contagious, and transmitted through air droplets and direct contact.
Transduction is:
- A. Transformation
- B. Transfer of genetic material between donor and recipient bacterial cells with the help of latent phage
- C. Transfer of large plasmids from a donor cell to a recipient cell
- D. None of the above
Correct Answer: B
Rationale: Transduction is the transfer of genetic material between bacterial cells with the help of a phage (virus). This process involves a phage infecting a bacterial cell, replicating inside it, and then transferring bacterial DNA along with phage DNA to another bacterial cell. This is different from transformation (choice A) which involves the uptake of naked DNA by a bacterial cell and plasmid transfer (choice C) which involves the transfer of small, circular DNA molecules. Therefore, the correct answer is B because it specifically describes the process of transduction in bacteria, while choices A and C describe different mechanisms of genetic transfer.
What are the two main targets currently used in anti-HIV therapy?
- A. Reverse transcriptase and something integrase
- B. Reverse transcriptase and protease
- C. Protease and integrase
- D. Viral glycoproteins gp120 and gp41
Correct Answer: B
Rationale: The correct answer is B: Reverse transcriptase and protease. Reverse transcriptase converts viral RNA into DNA, a crucial step in viral replication. Protease is responsible for cleaving viral polyproteins into functional proteins. Targeting both enzymes disrupts viral replication. Choice A is incorrect as integrase is not a main target in current therapy. Choice C is incorrect because protease is targeted along with reverse transcriptase, not integrase. Choice D is incorrect as targeting viral glycoproteins is not a main strategy in anti-HIV therapy.