Which initiates the coagulation cascade in vivo?

Correct Answer: C

Rationale: Correct Answer: C (Tissue factor) Rationale: 1. Tissue factor initiates the extrinsic pathway of the coagulation cascade by forming a complex with Factor VII. 2. This complex activates Factor X to Xa, leading to the common pathway of coagulation. 3. Factor XII is part of the intrinsic pathway and is not the primary initiator in vivo. 4. Thrombin is generated downstream in the cascade and amplifies coagulation but does not initiate it. 5. Factor X is activated further downstream in the common pathway and is not the primary initiator.

Correct Answer: A

Rationale: The correct answer is A: Mature B cell immunophenotype. In ALL, a mature B cell immunophenotype is associated with a poorer prognosis because it indicates that the leukemia cells have progressed to a more advanced stage of differentiation, making them more aggressive and resistant to treatment. On the other hand, choices B, C, and D are good prognostic factors in ALL. Female gender is associated with a better response to treatment, hyperploidy is a favorable genetic feature, and age 4-10 years is a common age group with a higher likelihood of responding well to treatment.

Correct Answer: A

Rationale: Step 1: Identify symptoms of viral hemorrhagic fever Step 2: Recall common viruses causing viral hemorrhagic fever Step 3: Understand characteristics of virus families Step 4: Filoviruses, like Ebola and Marburg, are known to cause viral hemorrhagic fevers due to their high pathogenicity. Step 5: Togaviruses, Bunyaviruses, and Flaviviruses are not typically associated with viral hemorrhagic fevers. Summary: Filovirus is the correct answer as it is a known cause of viral hemorrhagic fevers, while the other choices are not commonly associated with this condition.

Correct Answer: B

Rationale: The correct answer is B: Irradiating blood components. This is because irradiation of blood components helps prevent graft-versus-host disease by inactivating T lymphocytes present in the transfused blood. This decreases the risk of these donor T cells attacking the recipient's tissues, which is the underlying mechanism of graft-versus-host disease. Explanation of other choices: A: Packed cells - While packed red blood cells are less likely to cause a reaction compared to whole blood, they do not prevent graft-versus-host disease. C: Fresh whole blood - Fresh whole blood does not address the specific mechanism of graft-versus-host disease prevention like irradiation does. D: Crystalloid replacement - Crystalloid replacement does not have any impact on preventing graft-versus-host disease as it does not affect the T lymphocytes present in the transfused blood components.

Correct Answer: C

Rationale: The correct answer is C: Temporary water in jungles. Anopheles balabacensis is a species of mosquito known to breed in temporary water sources found in jungles. They typically lay their eggs in small, shallow pools of water that form after rainfalls. This choice is correct because it aligns with the known breeding habits of this particular mosquito species. A: Artificial containers - Incorrect. Anopheles balabacensis typically does not breed in artificial containers but prefers natural water sources. B: Drains - Incorrect. This species does not usually breed in drains but rather in natural water bodies. D: Rock pools - Incorrect. Anopheles balabacensis prefers temporary water in jungles over rock pools for breeding due to the specific environmental conditions required for egg-laying and larval development.