What is the role of second messengers in intracellular signaling pathways?

Correct Answer: B

Rationale: Second messengers amplify and transmit signals inside the cell.

Correct Answer: D

Rationale: Blood group antigens are present on RBC surfaces in fetal blood; they are inherited as dominant Mendelian traits, not recessive.

Correct Answer: B

Rationale: Reticulocytes (young RBCs) show a network when stained; mature RBCs are anucleate and flow faster in capillaries.

Correct Answer: A

Rationale: Lymph contains plasma proteins (e.g., albumin) and cells (lymphocytes); it absorbs fats, not amino acids, from the gut.

Correct Answer: A

Rationale: Hematocrit is measured by centrifugation; burns cause hemoconcentration, raising it.