Nokea
What is the structure of bacterial flagella?
- A. 9+2 microtubule arrangement
- B. protein filaments made of flagellin
- C. lipid bilayer
- D. peptidoglycan layer
Correct Answer: B
Rationale: The correct answer is B: protein filaments made of flagellin. Bacterial flagella are composed of flagellin proteins arranged in helical filaments. This structure allows for movement and propulsion of bacteria.
A: 9+2 microtubule arrangement is incorrect because this structure is typically found in eukaryotic flagella, not bacterial flagella.
C: Lipid bilayer is incorrect as it is a structural component of cell membranes, not bacterial flagella.
D: Peptidoglycan layer is incorrect as it is a component of bacterial cell walls, not flagella.
You may also like to solve these questions
The cell envelope of Gram-negative bacteria is composed of:
- A. Cytoplasmic membrane, a peptidoglycan layer and an outer membrane
- B. Cytoplasmic membrane and peptidoglycan layer
- C. Only peptidoglycan layer
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A because Gram-negative bacteria have a unique cell envelope structure consisting of a cytoplasmic membrane, a peptidoglycan layer, and an outer membrane. The cytoplasmic membrane is the innermost layer that separates the cytoplasm from the external environment. The peptidoglycan layer provides structural support to the cell. The outer membrane acts as an additional protective barrier and contains lipopolysaccharides. Choice B is incorrect because Gram-negative bacteria have an outer membrane in addition to the cytoplasmic membrane and peptidoglycan layer. Choice C is incorrect because Gram-negative bacteria have more than just a peptidoglycan layer in their cell envelope. Choice D is incorrect as the cell envelope of Gram-negative bacteria does have specific components.
Which of the following viruses belongs to family Arenaviridae?
- A. Rabies virus
- B. Crimean-Congo hemorrhagic fever virus
- C. Epstein-barr virus
- D. Lassa virus
Correct Answer: D
Rationale: The correct answer is D: Lassa virus. The rationale is as follows:
1. Lassa virus belongs to the family Arenaviridae, known for causing Lassa fever.
2. Rabies virus belongs to the Rhabdoviridae family.
3. Crimean-Congo hemorrhagic fever virus belongs to the Nairoviridae family.
4. Epstein-Barr virus belongs to the Herpesviridae family.
In summary, Lassa virus is the correct answer because it is the only virus listed that belongs to the Arenaviridae family.
A blood culture from a patient with sepsis revealed Gram-negative diplococci. The organism was oxidase-positive and fermentative. What is the most likely causative agent?
- A. Neisseria gonorrhoeae
- B. Neisseria meningitidis
- C. Haemophilus influenzae
- D. Moraxella catarrhalis
Correct Answer: B
Rationale: The correct answer is B: Neisseria meningitidis. This is because Neisseria meningitidis is a Gram-negative diplococci that is oxidase-positive and fermentative. Neisseria gonorrhoeae (choice A) is also a Gram-negative diplococci but is not fermentative. Haemophilus influenzae (choice C) is not a diplococci and Moraxella catarrhalis (choice D) is oxidase-negative. Thus, Neisseria meningitidis fits all the criteria provided in the question, making it the most likely causative agent for the sepsis in this patient.
A patient with fever and sore throat had a throat culture revealing Gram-positive cocci in chains. The bacteria were catalase-negative and beta-hemolytic. What is the most likely causative agent?
- A. Streptococcus pyogenes
- B. Streptococcus pneumoniae
- C. Enterococcus faecalis
- D. Staphylococcus aureus
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pyogenes.
1. Gram-positive cocci in chains: characteristic of Streptococcus species.
2. Catalase-negative: Streptococcus species are catalase-negative.
3. Beta-hemolytic: S. pyogenes is beta-hemolytic on blood agar.
Therefore, S. pyogenes fits all these criteria.
B: Streptococcus pneumoniae is catalase-negative but alpha-hemolytic, not beta-hemolytic.
C: Enterococcus faecalis is catalase-negative, but not typically beta-hemolytic or in chains.
D: Staphylococcus aureus is catalase-positive and not in chains.
Micrographia, a publication illustrating insects, sponges, as well as plant cells, was published by
- A. Robert Hooke
- B. Antony van Leeuwenhoek
- C. Hans Janssen
- D. John Needham
Correct Answer: A
Rationale: The correct answer is A: Robert Hooke. Hooke published Micrographia in 1665, showcasing detailed illustrations of insects, sponges, and plant cells under the microscope. Hooke's work was groundbreaking in advancing the field of microscopy. Van Leeuwenhoek is known for discovering microorganisms but did not publish Micrographia. Janssen and Needham were not associated with Micrographia. Therefore, A is the correct answer.