Nokea
Flagellin is:
- A. A protein
- B. A carbohydrate
- C. A staining method
- D. An organelle
Correct Answer: A
Rationale: Flagellin is a protein component of bacterial flagella. It is not a carbohydrate, staining method, or an organelle. The correct answer is A because flagellin is a structural protein that forms the flagellar filament. It helps in bacterial motility and pathogenicity. Therefore, the correct choice is A.
You may also like to solve these questions
Production of RNA from DNA is called
- A. Transposition
- B. Translation
- C. Transcription
- D. RNA splicing
Correct Answer: C
Rationale: The correct answer is C: Transcription. Transcription is the process of synthesizing RNA from a DNA template. During transcription, RNA polymerase binds to the DNA and produces a complementary RNA strand. This process is essential for gene expression.
Explanation for why other choices are incorrect:
A: Transposition involves the movement of genetic elements within a genome, not the production of RNA from DNA.
B: Translation is the process of synthesizing proteins from mRNA, not the production of RNA from DNA.
D: RNA splicing is the process of removing introns and joining exons in pre-mRNA to produce mature mRNA, not the initial production of RNA from DNA.
Production of auto-antibodies may be due to:
- A. Emergence of mutant clones of B cells
- B. Production of antibodies against hidden tissues
- C. Genetic factors
- D. All of these
Correct Answer: D
Rationale: Production of auto-antibodies can be due to various factors. Mutant B cell clones can lead to the production of self-reactive antibodies. Antibodies against hidden tissues can also trigger autoimmune responses. Genetic factors play a crucial role in predisposing individuals to autoimmunity. Therefore, the correct answer is D, as all these factors can contribute to the production of auto-antibodies. Choice A is incorrect as it only addresses one possible cause. Choice B is incorrect as it focuses solely on antibodies against hidden tissues. Choice C is incorrect as it overlooks the other potential reasons for auto-antibody production.
Which of the following is a feature of Gram-negative bacteria?
- A. Thick peptidoglycan layer
- B. Outer membrane with lipopolysaccharides
- C. Presence of teichoic acids
- D. Absence of a cell wall
Correct Answer: B
Rationale: The correct answer is B: Outer membrane with lipopolysaccharides. Gram-negative bacteria have an outer membrane containing lipopolysaccharides (LPS), which are important in pathogenesis and immune response. This feature is unique to Gram-negative bacteria, distinguishing them from Gram-positive bacteria (choice A). Teichoic acids (choice C) are found in the cell walls of Gram-positive bacteria, not Gram-negative. The statement in choice D, absence of a cell wall, is incorrect as all bacteria have a cell wall, although the composition may vary between Gram-negative and Gram-positive bacteria.
A 6-year-old child has duodenal ulcer. What antibacterial drug should be co-administered together with metronidazole and De-Nol in order to eradicate Helicobacter pylori infection?
- A. Amoxicillin
- B. Tetracycline
- C. Oleandomycin
- D. Biseptol
Correct Answer: A
Rationale: The correct answer is A: Amoxicillin. Amoxicillin is commonly used in combination therapy with metronidazole and bismuth compounds like De-Nol to eradicate Helicobacter pylori infection in children. Amoxicillin targets the bacterial cell wall synthesis, working synergistically with metronidazole to effectively eradicate the infection. Tetracycline (choice B) is not recommended in children under 8 years old due to potential tooth discoloration. Oleandomycin (choice C) is not commonly used for H. pylori infection. Biseptol (choice D) is a combination of sulfamethoxazole and trimethoprim, not typically used for H. pylori eradication.
Antigenic variation is used by bacteria to:
- A. evade host immune responses
- B. increase antibiotic susceptibility
- C. increase peptidoglycan synthesis
- D. enhance motility
Correct Answer: A
Rationale: The correct answer is A: evade host immune responses. Antigenic variation allows bacteria to change their surface antigens, making it difficult for the host immune system to recognize and attack them effectively. This enhances the bacteria's ability to evade immune responses and establish infection.
B: Increase antibiotic susceptibility is incorrect because antigenic variation does not directly impact the susceptibility of bacteria to antibiotics.
C: Increase peptidoglycan synthesis is incorrect because antigenic variation is not related to the synthesis of peptidoglycan, which is a major component of the bacterial cell wall.
D: Enhance motility is incorrect because antigenic variation does not directly affect the motility of bacteria.
In summary, antigenic variation in bacteria primarily serves to help them evade host immune responses, making option A the correct answer.