Nokea
Enzymatic reactions can be expressed in which of the following chemical notations?
- A. S + P = E
- B. P + P = E
- C. E + S = P
- D. S + S = P
Correct Answer: C
Rationale: The correct answer is C: E + S = P. This notation represents the interaction between an enzyme (E) and a substrate (S) resulting in a product (P). Enzymes facilitate chemical reactions by binding to substrates and converting them into products. Choice A is incorrect because it does not include the enzyme in the reaction. Choice B is incorrect as it involves two substrates binding to the enzyme, not a substrate converting to a product. Choice D is incorrect as it shows two substrates reacting to form a product without involvement of an enzyme. Thus, choice C accurately represents the process of enzymatic reactions involving enzymes, substrates, and products.
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Bacteria that have been identified as frequently responsible for nonsexually transmitted infections of the reproductive system include:
- A. Escherichia coli, Gardnerella vaginalis, and Staphylococcus aureus
- B. Streptococcus faecalis, Klebsiella oxytoca, and Serratia marcescens
- C. Clostridium tetani, Bacillus cereus, and Staphylococcus aureus
- D. Neisseria gonorrhoeae, Helicobacter pylori, and Pseudomonas aeruginosa
Correct Answer: A
Rationale: The correct answer is A (Escherichia coli, Gardnerella vaginalis, and Staphylococcus aureus) because they are known to commonly cause nonsexually transmitted infections of the reproductive system. Escherichia coli can cause urinary tract infections that can ascend to the reproductive system. Gardnerella vaginalis is associated with bacterial vaginosis, a common infection of the vagina. Staphylococcus aureus can cause infections in the reproductive system through various means.
Choices B, C, and D are incorrect:
B: Streptococcus faecalis, Klebsiella oxytoca, and Serratia marcescens are not commonly associated with reproductive system infections.
C: Clostridium tetani and Bacillus cereus are not typically involved in reproductive system infections.
D: Neisseria gonorrhoeae causes sexually transmitted infections, Helicobacter pylori causes gastrointestinal issues, and Pseudomonas aeruginosa is more
A bacteriophage is a(n) ____________ virus.
- A. helical
- B. icosahedral
- C. enveloped
- D. complex
Correct Answer: D
Rationale: The correct answer is D: complex. Bacteriophages are considered complex viruses because they have a complex structure consisting of a polyhedral head, a helical tail, and tail fibers. The head contains the viral genetic material, while the tail facilitates attachment to the host bacterial cell. This complexity distinguishes bacteriophages from simpler viruses like helical and icosahedral viruses. Helical viruses have a rod-like shape, while icosahedral viruses have a symmetrical, 20-sided structure. Enveloped viruses have a lipid bilayer envelope surrounding their capsid, which bacteriophages lack. Therefore, the unique and intricate structure of bacteriophages classifies them as complex viruses.
Endotoxins are released upon:
- A. bacterial replication
- B. cell lysis of gram-negative bacteria
- C. antibody production
- D. formation of spores
Correct Answer: B
Rationale: The correct answer is B because endotoxins are part of the outer membrane of gram-negative bacteria. When these bacteria undergo cell lysis, the endotoxins are released, causing harmful effects. This process does not occur during bacterial replication (choice A), antibody production (choice C), or formation of spores (choice D). Bacterial replication involves the creation of new bacterial cells, not the release of endotoxins. Antibody production is the immune response to pathogens, not the direct cause of endotoxin release. Spores are dormant structures formed by some bacteria, which are not directly related to the release of endotoxins.
The process of bacterial conjugation involves:
- A. DNA transfer via bacteriophage
- B. Uptake of naked DNA from the environment
- C. Direct transfer of DNA between two bacterial cells
- D. Binary fission
Correct Answer: C
Rationale: The correct answer is C: Direct transfer of DNA between two bacterial cells. In bacterial conjugation, genetic material is transferred directly from one bacterial cell to another through a conjugative pilus. This process involves physical contact between the cells, followed by the transfer of plasmid DNA or chromosomal DNA. This mechanism allows for the exchange of genetic information between bacteria, leading to genetic diversity.
Explanation of why other choices are incorrect:
A: DNA transfer via bacteriophage - Bacteriophage is a virus that infects bacteria and transfers its genetic material, but this is not the mechanism involved in bacterial conjugation.
B: Uptake of naked DNA from the environment - This process is known as transformation, where bacteria take up free DNA from the environment, but it is not specific to bacterial conjugation.
D: Binary fission - Binary fission is a form of asexual reproduction in bacteria where a single cell divides into two identical cells, and it is not related to the process
A patient had been provisionally diagnosed with syphilis. A laboratory assistant took the blood serum for an immunologic test based on the detection of antibodies preventing the movement of treponemas and causing their death. What reaction was used for the diagnosis?
- A. Immobilization
- B. Complement binding
- C. Agglutination
- D. Precipitation
Correct Answer: A
Rationale: The correct answer is A: Immobilization. This technique is called the Treponema pallidum immobilization (TPI) test, used to diagnose syphilis. The rationale is as follows:
1. TPI test detects antibodies that prevent the movement of treponemas, causing their death.
2. By immobilizing the treponemas, it indicates the presence of specific antibodies against syphilis.
3. This test is highly specific for syphilis diagnosis as it directly targets the causative agent.
Other choices are incorrect:
B: Complement binding - Not specific to syphilis, more commonly used for other diseases.
C: Agglutination - Detects clumping of particles, not specific to treponemas or syphilis.
D: Precipitation - Involves the formation of a solid, not directly related to treponema movement or death.