ATI RN
mcgraw hill microbiology test bank Questions
Question 1 of 5
4 days after a patient received a gunshot wound of the middle third of the thigh soft tissues his condition suddenly began deteriorating. There are complaints of bursting pain in the wound; pain increases during the last 12 hours. Edema of skin and hypodermic tissue quickly grows. Body temperature is 38,2oC, heart rate is 102/min. The wound edges gape, are dull in color; the muscles, viable as of day before, now protrude into the wound, look boiled, are dull in color, have dirty-grey coating and fall apart when being held with forceps. What infection has developed in the wound?
Correct Answer: A
Rationale: The correct answer is A: Anaerobic infection. The sudden deterioration, bursting pain, edema, foul appearance of wound, and presence of gas are indicative of gas gangrene caused by anaerobic bacteria like Clostridium perfringens. These bacteria thrive in low oxygen environments, such as deep wound tissues. The symptoms align with the classic presentation of gas gangrene, necessitating immediate surgical intervention.
Choice B: Aerobic gram-negative, is incorrect because anaerobic bacteria, not aerobic gram-negative bacteria, are responsible for gas gangrene.
Choice C: Putrid, is incorrect as it is a general term referring to foul-smelling decay and does not specify the type of infection.
Choice D: Aerobic gram-positive, is incorrect as gas gangrene is typically caused by anaerobic bacteria, not aerobic gram-positive bacteria.
Question 2 of 5
All of the following are methods for food preservation except
Correct Answer: B
Rationale: The correct answer is B: Disinfection. Disinfection is not a method for food preservation but rather a process of destroying harmful microorganisms on surfaces.
A: Pasteurization involves heating food to kill pathogens, preserving the food.
C: Irradiation uses radiation to kill bacteria and parasites, extending shelf life.
D: Ultrahigh-temperature pasteurization involves heating food at very high temperatures to extend shelf life.
In summary, disinfection is not a method used to preserve food but rather to clean surfaces.
Question 3 of 5
The enzyme that breaks down the peptidoglycan in bacterial cell walls is:
Correct Answer: A
Rationale: The correct answer is A: Lysozyme. Lysozyme is an enzyme that targets and breaks down the peptidoglycan in bacterial cell walls by cleaving the glycosidic bonds between the sugar components. This action weakens the cell wall, leading to bacterial cell lysis. Amylase (
B) breaks down starch, not peptidoglycan. Protease (
C) breaks down proteins, not peptidoglycan. Lipase (
D) breaks down lipids, not peptidoglycan.
Therefore, Lysozyme is the correct enzyme for breaking down peptidoglycan in bacterial cell walls.
Question 4 of 5
In order to accurately identify etiology of peptic ulcer disease, polymerase chain reaction (PCR) analysis was performed on gastric biopsy specimen taken from 47-year-old patient. Eventually, the test result was positive for H. pylori. Which of the following was most likely detected in PCR analysis?
Correct Answer: A
Rationale: The correct answer is A: Bacterial DNA. PCR analysis detects specific DNA sequences, so a positive result for H. pylori indicates the presence of the bacterial DNA in the gastric biopsy specimen. This method identifies the genetic material of the bacterium, not the bacterium itself (choice
C) or its toxins (choice
B). Additionally, PCR does not directly detect bacterial enzymes (choice
D) but rather focuses on genetic material for accurate identification.
Therefore, in this case, the detection of H. pylori in the PCR analysis points to the presence of bacterial DNA, confirming the etiology of peptic ulcer disease.
Question 5 of 5
The only way to get energy in haematrophic bacteria is:
Correct Answer: B
Rationale: The correct answer is B: Biological oxidation. Haematrophic bacteria obtain energy through biological oxidation, where they break down organic compounds to generate ATP for cellular processes. This process involves the transfer of electrons from the substrate to an electron transport chain to produce energy. Heat production (
A) is a byproduct of metabolism, not the primary way to obtain energy. In biosynthetic reactions (
C), energy is utilized rather than generated. Cultivation in culture media (
D) is a method of growing bacteria but does not directly provide energy.
Therefore, the correct answer is B as it aligns with the metabolic process of haematrophic bacteria.