Which big tarsal, apart from the talus, makes up the ankle?

Correct Answer: A

Rationale: The calcaneus (heel bone), alongside the talus, forms the ankle’s major structure, supporting weight and articulating with the tibia/fibula. Cuboid and navicular are more distal.

Correct Answer: C

Rationale: Flat bones, like the scapula (shoulder blade) and cranial bones, are thin and broad, providing a protective barrier for internal organs. The cranial bones protect the brain, while the scapula contributes to the shoulder structure, indirectly aiding in upper body protection. Although flat bones like those in the skull and sternum also produce blood cells in their marrow, their primary function is protection, making 'Protect internal organs' the correct answer.

Correct Answer: B

Rationale: Long bones are characterized by a cylindrical shape, with a shaft (diaphysis) and ends (epiphyses), and are primarily found in the limbs (e.g., femur, humerus). Short bones are cube-shaped (e.g., carpals), irregular bones have complex shapes (e.g., vertebrae), and flat bones are broad and thin (e.g., scapula), making 'Long bone' the correct answer.

Correct Answer: C

Rationale: Acetylcholine (ACh) is the neurotransmitter released by motor neurons into the synaptic cleft at the neuromuscular junction. It binds to receptors on the muscle fiber, initiating an action potential that leads to contraction. Serotonin, GABA, and dopamine have other neural roles, making 'Acetylcholine (ACh)' the correct answer.

Correct Answer: B

Rationale: In a relaxed muscle, tropomyosin covers the myosin-binding sites on actin filaments, preventing contraction. When calcium binds to troponin, it moves tropomyosin, exposing the sites for myosin attachment. Troponin regulates, myosin contracts, and collagen is structural, making 'Tropomyosin' the correct answer.