ATI RN
microbiology chapter 11 test bank Questions
Question 1 of 5
Axial filaments consist of
Correct Answer: A
Rationale: Axial filaments, also known as endoflagella, are composed of proteins. These proteins form a helical structure that enables certain bacteria, such as spirochetes, to move in a corkscrew-like motion. Proteins are the main structural component of axial filaments due to their flexibility and ability to generate movement.
Choice B, polyphosphates, are not typically associated with axial filaments, as they are more involved in energy storage and transfer.
Choice C, volutin granules, are storage inclusions of inorganic polyphosphate and are not part of axial filaments.
Choice D, carbohydrates, are not the primary component of axial filaments which are protein-based structures responsible for bacterial motility.
Question 2 of 5
Which bacteria is known for producing a neurotoxin that causes botulism?
Correct Answer: A
Rationale:
Step-by-step rationale:
1. Clostridium botulinum is known for producing the neurotoxin causing botulism.
2. Botulinum toxin paralyzes muscles, leading to symptoms of botulism.
3. Clostridium tetani produces tetanus toxin causing muscle rigidity, not botulism.
4. Streptococcus pneumoniae causes pneumonia, not botulism.
5. Escherichia coli can cause food poisoning, but not botulism.
Summary:
Choice A is correct (Clostridium botulinum) due to its association with botulism and neurotoxin production.
Choices B, C, and D are incorrect as they are associated with different diseases and toxins.
Question 3 of 5
Gram (-) bacteria have basal structure consisting of:
Correct Answer: C
Rationale: The correct answer is C: 4-10% of all materials building the cell wall. Gram (-) bacteria have a thin peptidoglycan layer making up 4-10% of the cell wall. This is in contrast to Gram (+) bacteria which have a thicker peptidoglycan layer.
Choice A is too high a percentage for Gram (-) bacteria.
Choice B is too low as it would not provide enough structural support.
Choice D is also too high and would not accurately reflect the composition of Gram (-) bacteria.
Question 4 of 5
A smear from a sore throat revealed rod-shaped bacteria with polar granules. What is the most likely causative agent?
Correct Answer: A
Rationale: The most likely causative agent is Corynebacterium diphtheriae.
Step 1: Presence of rod-shaped bacteria indicates a bacillus.
Step 2: Polar granules suggest metachromatic granules seen in C. diphtheriae.
Step 3: C. diphtheriae causes diphtheria, which presents with sore throat. Summary: B is incorrect as S. pneumoniae is a cocci, not a bacillus. C is incorrect as H. influenzae is a pleomorphic coccobacillus. D is incorrect as K. pneumoniae is a large, encapsulated bacillus.
Question 5 of 5
A patient's blood culture revealed Gram-positive rods capable of spore formation. They were also motile and produced gas in nutrient broth. What is the causative agent?
Correct Answer: A
Rationale: The correct answer is A: Clostridium perfringens. This bacterium fits all the characteristics mentioned: Gram-positive rods with spore formation, motile, and gas production in nutrient broth. Clostridium perfringens is known to cause gas gangrene, which aligns with the gas production in nutrient broth. Bacillus anthracis (
B) causes anthrax and does not typically produce gas. Clostridium tetani (
C) causes tetanus and does not form spores that are motile. Bacillus cereus (
D) is a common cause of food poisoning and does not cause gas gangrene.