Nokea
Bacterial families have general:
- A. Morphologic features
- B. Geographic features
- C. Historical features
- D. Physiologic features
Correct Answer: A
Rationale: The correct answer is A: Morphologic features. Bacterial families are classified based on their morphologic features such as shape, size, and arrangement. This classification helps in identifying and studying different bacterial species. Choice B, Geographic features, is incorrect as bacterial classification is not based on their geographic distribution. Choice C, Historical features, is incorrect as it does not play a role in the classification of bacterial families. Choice D, Physiologic features, is also incorrect as physiological characteristics are used for further classification within bacterial families, not as a general characteristic.
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A scolex is a structure found in:
- A. Enterobius vermicularis
- B. Necator americanus
- C. Ascaris lumbricoides
- D. Ancylostoma duodenale
Correct Answer: D
Rationale: The correct answer is D: Ancylostoma duodenale. A scolex is a structure found in tapeworms, not in the other options which are roundworms. Ancylostoma duodenale is a species of hookworm, a type of intestinal parasite that has a distinct scolex with hook-like mouthparts for attachment to the host's intestinal wall. Enterobius vermicularis is a pinworm, Necator americanus is a hookworm species without a scolex, and Ascaris lumbricoides is a roundworm with a cylindrical body lacking a scolex. Therefore, the presence of a scolex specifically points to Ancylostoma duodenale.
Which of the following viruses belong to the family Herpesviridae?
- A. Epstein-Barr virus
- B. Poxvirus
- C. SARS
- D. HIV
Correct Answer: A
Rationale: Step-by-step rationale for the correct answer (A: Epstein-Barr virus):
1. Epstein-Barr virus is a member of the Herpesviridae family, known for causing infectious mononucleosis.
2. Members of Herpesviridae have double-stranded DNA genomes and enveloped virions.
3. They establish latent infections in host cells and can reactivate periodically.
4. Poxvirus (B) belongs to the Poxviridae family, not Herpesviridae.
5. SARS (C) is caused by a coronavirus, not a herpesvirus.
6. HIV (D) belongs to the Retroviridae family, not Herpesviridae.
Summary: The correct answer is A because Epstein-Barr virus is a member of the Herpesviridae family, exhibiting specific characteristics distinct from the other choices.
An enzyme process of producing two identical copies of DNA from one original DNA molecule is called:
- A. Translation
- B. Transcription
- C. Replication
- D. Cell division
Correct Answer: C
Rationale: The correct answer is C: Replication. In DNA replication, the original DNA molecule is unwound and each strand serves as a template to synthesize a new complementary strand. This results in two identical copies of the original DNA molecule. Translation (A) is the process of synthesizing proteins from mRNA. Transcription (B) is the process of synthesizing mRNA from DNA. Cell division (D) is the process of a cell dividing into two daughter cells, not specifically producing identical DNA copies. Therefore, replication is the correct answer as it specifically refers to the process of copying DNA to produce two identical copies.
The role of adhesins in gram positive bacteria is carried out by:
- A. Lipoteichoic acids
- B. Fimbriae
- C. Flagella
- D. Short chain mycolic chains
Correct Answer: A
Rationale: Adhesins in gram positive bacteria are typically carried out by surface structures such as lipoteichoic acids. These molecules help the bacteria adhere to host cells or tissues. Lipoteichoic acids are specific to gram positive bacteria and play a crucial role in initiating infections. Fimbriae, flagella, and short chain mycolic acids are not primarily responsible for adhesion in gram positive bacteria. Fimbriae are more commonly found in gram negative bacteria, flagella are involved in motility, and short chain mycolic acids are specific to mycobacteria. Therefore, the correct answer is A, lipoteichoic acids.
A wound smear revealed Gram-negative rods producing blue-green pigment. The bacteria had a fruity odor. What is the causative agent?
- A. Pseudomonas aeruginosa
- B. Escherichia coli
- C. Klebsiella pneumoniae
- D. Proteus mirabilis
Correct Answer: A
Rationale: The correct answer is A: Pseudomonas aeruginosa. Pseudomonas aeruginosa is known to produce a blue-green pigment called pyocyanin, which is characteristic of the organism. Additionally, it has a distinct fruity odor due to the production of certain volatile compounds. Escherichia coli (B) does not produce blue-green pigment or have a fruity odor. Klebsiella pneumoniae (C) and Proteus mirabilis (D) also do not exhibit these specific characteristics associated with Pseudomonas aeruginosa.