Nokea
The spore in the cells of Clostridium tetani is located:
- A. Paracentrally
- B. Subterminally
- C. Centrally
- D. Terminally
Correct Answer: D
Rationale: The correct answer is D: Terminally. In Clostridium tetani, spores are located at the terminal end of the cell. This positioning helps the spores to be released easily when the cell lyses, aiding in the spread of the bacteria. Paracentrally (A) and centrally (C) would not be as efficient for spore release. Subterminally (B) is also incorrect as the spores are specifically located at the terminal end of the cell, not just near it.
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Which bacteria is responsible for causing the disease known as leprosy?
- A. Mycobacterium leprae
- B. Neisseria gonorrhoeae
- C. Streptococcus pneumoniae
- D. Clostridium perfringens
Correct Answer: A
Rationale: The correct answer is A: Mycobacterium leprae. This bacterium is responsible for causing leprosy. Mycobacterium leprae is a slow-growing bacterium that affects the skin and nerves, leading to the characteristic symptoms of leprosy. Neisseria gonorrhoeae is a sexually transmitted bacterium causing gonorrhea. Streptococcus pneumoniae causes pneumonia and other respiratory infections. Clostridium perfringens is associated with food poisoning and gas gangrene. Therefore, the correct answer is A because Mycobacterium leprae specifically causes leprosy, while the other choices are associated with different diseases.
For which family the following morphological features are typical: filamentous spiral nucleocapsid, linear unsegmented single strand (-) RNA and lipid bilayer membrane of cellular origin:
- A. Picornaviridae
- B. Filoviridae
- C. Orthomyxoviridae
- D. Togaviridae
Correct Answer: B
Rationale: Step-by-step rationale:
1. Filamentous spiral nucleocapsid is characteristic of Filoviridae, such as Ebola virus.
2. Linear unsegmented single strand (-) RNA is a key feature of Filoviridae genomes.
3. The lipid bilayer membrane of cellular origin is found in Filoviridae viruses.
4. Therefore, the correct answer is B (Filoviridae) due to the alignment of all three morphological features.
Summary:
- A (Picornaviridae): Has an icosahedral capsid, not filamentous spiral.
- C (Orthomyxoviridae): Has a segmented genome, not linear unsegmented.
- D (Togaviridae): Has a spherical capsid, not filamentous spiral.
Which type of bacteria have an outer membrane containing lipopolysaccharides (LPS)?
- A. Gram-positive bacteria
- B. Gram-negative bacteria
- C. Both Gram-positive and Gram-negative bacteria
- D. Neither Gram-positive nor Gram-negative bacteria
Correct Answer: B
Rationale: The correct answer is B: Gram-negative bacteria. Gram-negative bacteria have an outer membrane containing lipopolysaccharides (LPS). In the Gram staining technique, these bacteria appear pink/red due to the thin peptidoglycan layer, which allows the crystal violet stain to be washed out, revealing the safranin counterstain. Gram-positive bacteria (choice A) have a thick peptidoglycan layer but lack an outer membrane with LPS. Choice C is incorrect since only Gram-negative bacteria possess LPS in their outer membrane. Choice D is incorrect as all bacteria can be classified as either Gram-positive or Gram-negative based on their cell wall structure.
Examples for chemical vaccines are:
- A. Salk vaccine
- B. HPV vaccine
- C. Sabin vaccine
- D. Shiga anatoxin
Correct Answer: D
Rationale: The correct answer is D, Shiga anatoxin. This is because the Salk and Sabin vaccines are actually for polio, not chemical vaccines. HPV vaccine is a biological vaccine, not a chemical one. Shiga anatoxin is a chemical vaccine used against Shigella bacteria, making it the only correct choice for chemical vaccines in this question.
The net gain of ATP molecules after the breakdown of one glucose molecule in glycolysis is
- A. 1
- B. 2
- C. 3
- D. 4
Correct Answer: B
Rationale: The correct answer is B (2). During glycolysis, one glucose molecule is broken down into two molecules of pyruvate. In this process, a net gain of 2 ATP molecules is produced through substrate-level phosphorylation. Specifically, ATP is generated during the conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate and during the conversion of phosphoenolpyruvate to pyruvate. The other choices are incorrect because the net gain of ATP molecules in glycolysis is not 1, 3, or 4; it is 2 based on the specific enzymatic reactions involved in the pathway.