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Which of the following organisms produces toxins that target cholesterol?
- A. Streptococcus pyogenes
- B. Corynebacterium diphtheriae
- C. Escherichia coli
- D. Aeromonas hydrophila
Correct Answer: C
Rationale: Step 1: Escherichia coli is known to produce a toxin called colibactin that targets cholesterol.
Step 2: Colibactin disrupts cholesterol metabolism in host cells.
Step 3: This disruption can lead to various health issues.
Step 4: Streptococcus pyogenes produces different toxins, not specifically targeting cholesterol.
Step 5: Corynebacterium diphtheriae produces diphtheria toxin, not targeting cholesterol.
Step 6: Aeromonas hydrophila produces various toxins, but not known for targeting cholesterol.
Summary: Escherichia coli produces toxins that specifically target cholesterol, making it the correct choice over the other options.
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Agglutination reaction is one of the following
- A. Ascoli ring test
- B. Western blot
- C. ELISA
- D. Reaction type Gruber
Correct Answer: A
Rationale: The correct answer is A: Ascoli ring test. Agglutination reaction in the Ascoli ring test is characterized by the formation of a visible ring at the interface of antigen and antibody. This reaction specifically tests for the presence of specific antibodies against antigens in serum, indicating a recent or current infection. The other options, Western blot, ELISA, and Reaction type Gruber, do not involve the agglutination reaction. Western blot and ELISA are immunoassay techniques that detect specific antibodies or antigens, while Reaction type Gruber is not a recognized method in immunology. Therefore, the Ascoli ring test is the correct choice for a test involving agglutination reaction.
The main structure components of Viruses are:
- A. Glycoproteins and proteins
- B. Nucleic acids and lipids
- C. Nucleic acid and proteins
- D. Lipids and proteins
Correct Answer: C
Rationale: The correct answer is C: Nucleic acid and proteins. Viruses contain genetic material in the form of nucleic acids (DNA or RNA) surrounded by a protein coat. This genetic material carries instructions for viral replication. Proteins are also essential components of viruses, serving various functions like facilitating viral entry into host cells. Option A is incorrect as lipids are not main components of viruses. Option B is incorrect as lipids are not typically found in the main structure of viruses. Option D is incorrect as lipids are not primary components of viruses, and glycoproteins are not always present in the main structure of viruses.
The development of polioviruses on cell cultures is characterized by:
- A. Cytopathic effect
- B. Cytotoxic effect
- C. Cytolytic effect
- D. They Don't Change The Cell Cultures
Correct Answer: A
Rationale: The correct answer is A: Cytopathic effect. This is because polioviruses cause visible changes in infected cells, leading to cell damage and death, known as cytopathic effect. This is a key characteristic of viral infection. Choice B (Cytotoxic effect) is incorrect as it refers to the toxicity of a substance to cells, not the specific effect of polioviruses. Choice C (Cytolytic effect) is incorrect as it specifically refers to cell lysis, which is not the primary mechanism of poliovirus infection. Choice D (They Don't Change The Cell Cultures) is incorrect because polioviruses do indeed cause changes in cell cultures due to their cytopathic effect.
Production of RNA and DNA is called
- A. RNA splicing
- B. Translation
- C. Transposition
- D. Transcription
Correct Answer: D
Rationale: The correct answer is D: Transcription. This is the process where the DNA sequence is copied into an RNA molecule. It is the initial step in gene expression.
A: RNA splicing is the process of removing introns from pre-mRNA to create a mature mRNA molecule.
B: Translation is the process of synthesizing proteins using the information from mRNA.
C: Transposition is the movement of genetic elements within a genome.
In summary, transcription specifically refers to the synthesis of RNA from DNA, making it the correct choice compared to the other options.
The bacteria that causes whooping cough is:
- A. Bordetella pertussis
- B. Haemophilus influenzae
- C. Pseudomonas aeruginosa
- D. Streptococcus pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Bordetella pertussis. Whooping cough is caused by this bacteria, which specifically infects the respiratory tract. Bordetella pertussis produces toxins that lead to the characteristic symptoms of the disease. Haemophilus influenzae, Pseudomonas aeruginosa, and Streptococcus pneumoniae are not the causative agents of whooping cough. Haemophilus influenzae can cause respiratory infections, Pseudomonas aeruginosa is associated with hospital-acquired infections, and Streptococcus pneumoniae is a common cause of pneumonia and other respiratory infections, but none of these bacteria are responsible for whooping cough.