Nokea
Defensins are
- A. Released by mast cells during an allergic reaction
- B. Membrane-disrupting peptides
- C. Acute phase proteins
- D. Opsonins
Correct Answer: B
Rationale: The correct answer is B: Membrane-disrupting peptides. Defensins are antimicrobial peptides that disrupt bacterial cell membranes. This disrupts the integrity of the bacterial cell, leading to cell lysis and death. Choice A is incorrect because mast cells release histamines, not defensins. Choice C is incorrect as acute phase proteins are involved in the immune response to inflammation. Choice D is incorrect as opsonins are molecules that enhance phagocytosis of pathogens by immune cells.
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What underpins most functions of the immune system?
- A. Secondary lymphoid tissues
- B. Haematopoietic stem cells in the bone marrow
- C. Mucosal immune system activity
- D. Rapid cytokine suppression
Correct Answer: B
Rationale: The correct answer is B: Haematopoietic stem cells in the bone marrow. These cells are responsible for generating all immune cells, including lymphocytes, macrophages, and dendritic cells. They continuously replenish the immune system, allowing for proper immune function. Secondary lymphoid tissues (choice A) play a role in immune responses but are not the primary underpinning. Mucosal immune system activity (choice C) is important for defense at mucosal surfaces but is not the foundation of immune function. Rapid cytokine suppression (choice D) is a regulatory mechanism, not the fundamental basis of immune system functions.
Which complement components are primarily involved in Type III hypersensitivity?
- A. C1 and C4
- B. C3a and C5a
- C. C5b and C6
- D. C2 and C7
Correct Answer: B
Rationale: The correct answer is B: C3a and C5a. In Type III hypersensitivity reactions, immune complexes form and deposit in tissues, leading to complement activation. C3a and C5a are anaphylatoxins released during complement activation, causing inflammation and tissue damage in Type III hypersensitivity.
Rationale:
A: C1 and C4 are primarily involved in Type I hypersensitivity reactions.
C: C5b and C6 are part of the membrane attack complex in the classical pathway of complement activation, not specific to Type III hypersensitivity.
D: C2 and C7 are involved in the classical pathway of complement activation but not directly implicated in Type III hypersensitivity reactions.
A patient who has a large amount of carbon dioxide in the blood also has what in the blood?
- A. Large amount of carbonic acid and low hydrogen ion concentration
- B. Small amount of carbonic acid and low hydrogen ion concentration
- C. Large amount of carbonic acid and high hydrogen ion concentration
- D. Small amount of carbonic acid and high hydrogen ion concentration
Correct Answer: C
Rationale: Excess CO2 forms carbonic acid, increasing hydrogen ion concentration and lowering pH.
Which of the following characteristics do not occur in prokaryotic cells?
- A. cellular organization
- B. thylakoid membranes within chloroplasts
- C. oxygenic photosynthesis
- D. anaerobic respiration
Correct Answer: B
Rationale: The correct answer is B: thylakoid membranes within chloroplasts. Prokaryotic cells lack membrane-bound organelles like chloroplasts, where thylakoid membranes are found. This is a key feature of prokaryotic cells. Choices A, C, and D are characteristics that can occur in prokaryotic cells. Cellular organization is present in prokaryotic cells, oxygenic photosynthesis can be carried out by some prokaryotic organisms, and prokaryotic cells can perform anaerobic respiration.
What type of cell is responsible for carrying oxygen and carbon dioxide in the body?
- A. Red blood cell
- B. White blood cell
- C. Platelet
- D. Hematocrit
Correct Answer: A
Rationale: The correct answer is A: Red blood cell. Red blood cells, also known as erythrocytes, contain hemoglobin that binds to oxygen and carbon dioxide for transport in the bloodstream. They are specifically designed for gas exchange. White blood cells (B) are part of the immune system and fight infections. Platelets (C) are responsible for blood clotting. Hematocrit (D) refers to the proportion of red blood cells in the blood, not a specific type of cell responsible for gas transport.