The antibiotics penicillin and cephalosporin are produced by:

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microbiology chapter 12 test bank Questions

Question 1 of 9

The antibiotics penicillin and cephalosporin are produced by:

Correct Answer: C

Rationale: The correct answer is C: fungi. Both penicillin and cephalosporin are produced by certain species of fungi. Penicillin is derived from the Penicillium fungi, while cephalosporin is produced by Cephalosporium fungi. Fungi have the ability to synthesize these antibiotics as part of their defense mechanisms against other microorganisms. Algae (A), slime molds (B), and protozoans (D) do not have the capability to produce antibiotics like penicillin and cephalosporin. Algae are mainly photosynthetic organisms, slime molds are protists that lack the ability to synthesize complex antibiotics, and protozoans are single-celled eukaryotic organisms that do not produce antibiotics like fungi do.

Question 2 of 9

Microorganisms of various species are often organized into complex communities on a surface and are called __________.

Correct Answer: B

Rationale: The correct answer is B: biofilms. Biofilms are structured communities of microorganisms that adhere to a surface and are embedded in a matrix. This is the most appropriate term as it specifically describes the organization of various species into complex communities on a surface. Colonies (A) refer to groups of cells of the same species, not necessarily multiple species. Ecosystems (C) are broader systems involving interactions between living organisms and their environment. Plagues (D) are outbreaks of disease, not a term used to describe organized microbial communities.

Question 3 of 9

Media that contain complex organic substances such as blood for the growth of specific bacteria are referred to as:

Correct Answer: A

Rationale: The correct answer is A: enriched media. Enriched media contain additional nutrients such as blood to support the growth of fastidious bacteria. This allows for the cultivation of a wider range of microorganisms. General-purpose media (B) contain basic nutrients for a variety of bacteria. Reducing media (C) create anaerobic conditions, not necessarily rich in organic substances. Differential media (D) contain indicators to distinguish between different types of microorganisms, not necessarily enriched with organic substances.

Question 4 of 9

Gram (+) bacteria ... MG-ribonucleate and Mg. deoxyribonucleate in:

Correct Answer: A

Rationale: The correct answer is A, proportion 4:1. Gram (+) bacteria have a higher ratio of MG-ribonucleate to Mg. deoxyribonucleate because ribosomal RNA is more abundant in actively growing bacterial cells. This higher proportion of MG-ribonucleate to Mg. deoxyribonucleate is essential for protein synthesis and growth. The other choices are incorrect because they do not reflect the higher ratio of ribosomal RNA to DNA in Gram (+) bacteria, which is crucial for their metabolic activities and cellular functions.

Question 5 of 9

Which one is true for the bacterial cell?

Correct Answer: D

Rationale: The correct answer is D: Multiplies by binary fission. Bacterial cells reproduce through binary fission, where a single cell divides into two identical daughter cells. This process is essential for bacterial growth and multiplication. A: The oxidative phosphorylation does not take place in the mitochondria of bacterial cells but in the cell membrane. B: Capsules are not organelles but outer protective layers found in some bacterial cells. C: Bacterial cells contain both DNA and RNA, essential for their genetic information and protein synthesis.

Question 6 of 9

A patient with abdominal pain had a stool culture revealing non-lactose-fermenting, Gram-negative rods that produced gas in a nutrient broth. What is the most likely causative agent?

Correct Answer: D

Rationale: The correct answer is D: Proteus vulgaris. This is because Proteus species are non-lactose-fermenting Gram-negative rods that are known to produce gas in nutrient broths. Proteus vulgaris is commonly associated with urinary tract infections and can also cause abdominal infections. A: Salmonella typhi typically causes typhoid fever and is not known to produce gas in nutrient broths. B: Shigella dysenteriae is a causative agent of dysentery and does not typically produce gas in nutrient broths. C: Escherichia coli is a lactose-fermenting bacterium and does not fit the description of the organism in the stool culture.

Question 7 of 9

What is the mechanism of action of the exotoxin C. Diphtheriae?

Correct Answer: C

Rationale: The correct answer is C: Inhibits protein synthesis. Exotoxin of C. Diphtheriae acts by inhibiting protein synthesis in host cells. This disrupts cellular functions and leads to tissue damage. Choice A is incorrect because acetylcholine release is not affected. Choice B is incorrect as it does not involve neurotransmitters. Choice D is incorrect as the exotoxin does have a specific mechanism.

Question 8 of 9

Infection of several persons without any epidemiological link is

Correct Answer: B

Rationale: The correct answer is B: sporadic disease. Infection of several persons without any epidemiological link is considered sporadic because it occurs in a random and isolated manner, with no clear pattern or connection between cases. It is not classified as an epidemic (A) because it does not involve a sudden increase in the number of cases within a specific population. It is also not endemic (C) as endemic diseases are constantly present in a particular region or population. Lastly, it is not a pandemic (D) which refers to a global outbreak affecting a large number of people across different countries.

Question 9 of 9

A 33 year old patient was delivered to the infectious diseases department on the 7-th day of disease. He complained about great weakness, high temperature, pain in the lumbar area and leg muscles, icteritiousness, dark color of urine, headache. The acute disease started with chill, body temperature rise up to 40oC, headache, pain in the lumbar area and sural muscles. Icterus turned up on the 4th day, nasal and scleral haemorrhages came on the 5th day. Fever has lasted for 6 days. Diuresis - 200 ml. What is the most probable diagnosis?

Correct Answer: A

Rationale: The most probable diagnosis is Leptospirosis. The symptoms described align with the classic presentation of Leptospirosis, such as fever, muscle pain, headache, jaundice, and hemorrhages. The initial symptoms of chills, high fever, and muscle pain followed by jaundice and hemorrhages are characteristic of Leptospirosis. The presence of dark urine and low diuresis also point towards kidney involvement, which is common in Leptospirosis due to renal failure. Additionally, the patient's history of potential exposure to contaminated water or soil supports the diagnosis, as Leptospirosis is commonly transmitted through contact with infected animal urine. Summary of other choices: - Typhoid fever typically presents with sustained fever, abdominal pain, and constipation, not matching the symptoms described. - Virus A hepatitis usually presents with jaundice, but other symptoms such as muscle pain and hemorrhages are not typical. - Sepsis is a systemic response

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