Nokea
The movement of molecules through a membrane from an area of high hydrostatic pressure to an area of lower hydrostatic pressure is:
- A. filtration
- B. exocytosis
- C. simple diffusion
- D. simple diffusion
Correct Answer: D
Rationale: The correct answer is D: simple diffusion. In simple diffusion, molecules move from an area of high concentration to low concentration without the need for energy input. Hydrostatic pressure is a form of passive transport that drives molecules to equalize concentration. Filtration (A) involves the movement of solutes through a membrane under pressure. Exocytosis (B) is the process by which cells release substances outside the cell using energy. Osmosis (C) is the movement of water molecules across a selectively permeable membrane. Therefore, simple diffusion is the most appropriate choice in this scenario.
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The typical site for replication of DNA viruses is:
- A. Nucleus
- B. Cytoplasm
- C. Endoplasmic Reticulum
- D. Golgi Apparatus
Correct Answer: A
Rationale: The correct answer is A: Nucleus. DNA viruses replicate in the host cell's nucleus because they require access to the host cell's DNA replication machinery. The nucleus contains the necessary enzymes and factors for DNA replication to occur accurately. The DNA viruses need to utilize these host cell components to replicate their own genetic material.
Summary of why other choices are incorrect:
B: Cytoplasm - Cytoplasm lacks the necessary enzymes and machinery for accurate DNA replication.
C: Endoplasmic Reticulum - ER is involved in protein synthesis and processing, not DNA replication.
D: Golgi Apparatus - Golgi apparatus is responsible for processing and packaging proteins, not DNA replication.
Acne is caused by:
- A. Staphylococcus aureus
- B. Staphylococcus epidermidis
- C. Streptococcus pyogenes
- D. Propionibacterium acnes
Correct Answer: D
Rationale: The correct answer is D: Propionibacterium acnes. This bacterium plays a key role in acne formation by colonizing hair follicles, leading to inflammation and acne lesions. It produces fatty acids that contribute to the development of acne. Staphylococcus aureus (A) and Staphylococcus epidermidis (B) are not directly linked to acne. Streptococcus pyogenes (C) is associated with skin infections but not acne. In summary, Propionibacterium acnes is the primary bacterium responsible for acne due to its ability to induce inflammation and follicular blockages.
Enriched growth media:
- A. Belong to the minimal media and inhibit the development of gram+ cocci
- B. Support the development of the target bacteria groups without suppressing the growth of other microorganisms
- C. Are intended for the cultivation of only one microbial species
- D. Support the development of target bacteria groups and suppress the development of other microorganisms
Correct Answer: B
Rationale: The correct answer is B because enriched growth media provide essential nutrients that support the growth of target bacteria groups without inhibiting the growth of other microorganisms. This allows for the selective cultivation of specific microbes while still allowing for the growth of other organisms present in the sample. Choice A is incorrect because enriched media do not belong to minimal media and do not inhibit the development of gram+ cocci. Choice C is incorrect because enriched media can support the growth of multiple microbial species. Choice D is incorrect because enriched media do not suppress the development of other microorganisms but rather provide nutrients to support their growth alongside the target bacteria groups.
The structure used for bacterial motility is:
- A. Fimbriae
- B. Capsule
- C. Flagella
- D. Pili
Correct Answer: C
Rationale: The correct answer is C: Flagella. Flagella are the structures used for bacterial motility, allowing bacteria to move towards or away from stimuli. They are long, whip-like appendages that rotate to propel the bacteria. Fimbriae (A) are short, hair-like structures used for attachment, not movement. Capsules (B) are protective layers surrounding bacteria. Pili (D) are used for adherence and conjugation, not motility. In summary, flagella are specifically designed for bacterial movement, making them the correct choice.
A child with diarrhea had stool microscopy revealing cysts with four nuclei. What is the most likely causative agent?
- A. Entamoeba histolytica
- B. Giardia lamblia
- C. Balantidium coli
- D. Trichomonas hominis
Correct Answer: A
Rationale: The correct answer is A: Entamoeba histolytica. This pathogen is known to cause amoebic dysentery, characterized by diarrhea with bloody or mucoid stools. The presence of cysts with four nuclei in the stool microscopy is a characteristic feature of Entamoeba histolytica. Other choices are incorrect because Giardia lamblia typically presents with binucleate cysts, Balantidium coli is a ciliated protozoan, and Trichomonas hominis is a non-pathogenic parasite found in the human intestine.