What is the origin of the wrist flexors?

Correct Answer: B

Rationale: Wrist flexors (e.g., flexor carpi radialis) originate from the medial epicondyle of the humerus, a bony prominence anchoring forearm flexors. Lateral epicondyle hosts extensors (e.g., extensor carpi). Carpals are distal, not origins. Deltoid tuberosity relates to deltoid, not wrist. Medial epicondyle's role distinguishes it, key for wrist flexion leverage.

Correct Answer: A

Rationale: Solubility of most solids in liquids rises with temperature because higher thermal energy enhances molecular motion, breaking solute-solute bonds and increasing solvent-solute interactions. For example, sugar dissolves better in hot water. Pressure affects gases more than solids, and decreasing temperature typically reduces solubility, as seen in crystallization. Lower pressure has minimal impact. This temperature-driven solubility increase, rooted in thermodynamics, applies broadly to ionic and polar solids, distinguishing it from gas solubility dynamics.

Correct Answer: A

Rationale: Cellular respiration in animals breaks down glucose with oxygen to produce energy. This process glycolysis, Krebs cycle, and electron transport chain yields ATP, the cell's energy currency, powering functions like muscle movement. Oxygen is a reactant, not a product, while RNA and DNA are genetic molecules, not respiration outputs. ATP's role as the direct energy product, formed via oxidative phosphorylation, marks it as the primary outcome, essential for cellular work and distinguishing it from structural or input substances.

Correct Answer: D

Rationale: Acetylcholine (Ach), released by somatic motor neurons, excites skeletal muscle fibers by binding nicotinic receptors, opening Na⁺ channels to depolarize the sarcolemma, initiating contraction. GABA, inhibitory in the CNS, doesn't excite muscle. Na⁺ is an ion, not a neurotransmitter it enters post-Ach binding. Ca²⁺ triggers contraction internally, not as a neurotransmitter. Ach's excitatory role at the neuromuscular junction distinguishes it, key for signal transmission, unlike inhibitory, ionic, or intracellular agents.

Correct Answer: D

Rationale: Muscle names encode specific traits. Quadriceps femoris combines quadriceps, indicating four origins four distinct attachment points on the pelvis or femur with femoris, pinpointing its location on the thigh's femur bone. Action (e.g., extension) isn't specified, nor are insertion points (tibia via patella) or fibre direction (e.g., rectus). Location and origin count align with naming conventions, as seen in biceps or triceps, where number denotes origins and the second term locates it. This reflects skeletal muscle nomenclature's focus on anatomical anchors, distinguishing it from action-based or directional terms, crucial for identifying muscles in clinical and educational contexts.