Nokea
Bacterial spores are used for:
- A. Protection against phagocytosis
- B. Reproduction
- C. Survival
- D. Nutrient storage
Correct Answer: C
Rationale: The correct answer is C: Survival. Bacterial spores are specialized structures that bacteria form to survive harsh conditions such as extreme temperatures or lack of nutrients. Spores are not used for protection against phagocytosis (A) as they are dormant structures and not actively involved in defense mechanisms. They are not for reproduction (B) as spores are a form of bacterial reproduction but not the primary purpose of spore formation. Spores do not serve as nutrient storage (D) as they are mainly used for survival during unfavorable conditions.
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Which of the following transport mechanisms transports water across the plasma membrane?
- A. osmosis
- B. facilitated diffusion
- C. phagocytosis
- D. exocytosis
Correct Answer: A
Rationale: Osmosis is the correct answer because it is the process by which water molecules move across a semi-permeable membrane from an area of low solute concentration to an area of high solute concentration. This movement occurs passively, driven by the concentration gradient. Facilitated diffusion (B) involves the transport of specific molecules with the help of carrier proteins, not water. Phagocytosis (C) is a process where cells engulf solid particles, not water molecules. Exocytosis (D) is the process of releasing substances from a cell by fusion of vesicles with the cell membrane, not the transport of water across the membrane.
Which scientist performed the first successful vaccination against smallpox?
- A. Pasteur
- B. Jenner
- C. Semmelweis
- D. Koch
Correct Answer: B
Rationale: The correct answer is B: Jenner. Edward Jenner is credited with performing the first successful vaccination against smallpox in 1796. He used cowpox virus to inoculate individuals, leading to immunity against smallpox. Jenner's experiment laid the foundation for modern vaccination. Pasteur (A) is known for developing the germ theory of disease. Semmelweis (C) advocated for handwashing to prevent infections. Koch (D) identified the causative agents of several diseases but did not develop the smallpox vaccine.
The organisms to be identified have a nucleus surrounded by a nuclear membrane. Genetic material is concentrated predominantly in the chromosomes which consist of DNA strands and protein molecules. These cells divide mitotically. Identify these organisms:
- A. Eukaryotes
- B. Bacteriophages
- C. Prokaryotes
- D. Viruses
Correct Answer: A
Rationale: Step-by-step rationale:
1. The presence of a nucleus with a nuclear membrane indicates eukaryotic cells.
2. Eukaryotes have genetic material in chromosomes made of DNA and proteins.
3. Mitotic division is characteristic of eukaryotic cells.
4. Therefore, the organisms described are eukaryotes.
Summary:
- Bacteriophages (B) are viruses that infect bacteria.
- Prokaryotes (C) lack a nucleus and their genetic material is not organized into chromosomes.
- Viruses (D) are not considered living organisms and do not have a nucleus or chromosomes.
After the transfer of the F plasmid from the donor to the recipient cell..
- A. It is not possible to predict the outcome
- B. The donor cells become F
- C. The two cells become F
- D. The two cells become F+
Correct Answer: D
Rationale: After the transfer of the F plasmid from the donor to the recipient cell, the correct answer is D. This is because the F plasmid carries genes for conjugation, allowing the recipient cell to become F+ (containing the F plasmid). The donor cell remains F. Choice A is incorrect as the outcome can be predicted based on the transfer of the F plasmid. Choice B is incorrect because the donor cell does not become F after transferring the F plasmid. Choice C is incorrect as only the recipient cell becomes F+, not both cells.
Patients planned for treatment with monoclonal antibodies are tested for:
- A. HBV
- B. HCV
- C. M. tuberculosis
- D. All are correct
Correct Answer: D
Rationale: The correct answer is D: All are correct. Patients planned for treatment with monoclonal antibodies should be tested for HBV, HCV, and M. tuberculosis due to the risk of reactivation of these infections during treatment. HBV and HCV reactivation can lead to severe liver damage, while M. tuberculosis reactivation can cause serious respiratory complications. Testing for all three infections helps in identifying and managing any pre-existing infections to ensure patient safety during monoclonal antibody treatment. Choices A, B, and C are incorrect because each of these infections presents specific risks that need to be assessed before initiating monoclonal antibody therapy.