Question

during exercise, sensory receptors detect changes in oxygen and carbon dioxide levels in the blood. this information is then sent to the brain’s medulla, which causes the heart to beat faster and increases the rate of breathing. exercising also causes the nervous system to signal the pancreas and thyroid gland to release hormones which regulate metabolism. which statement is best demonstrated by this scenario? a. exercise is important for the body to function properly. b. hormones act as signal molecules between all body systems. c. increased heart rate and blood flow decrease oxygen supply. d. nerves transmit and respond to every major system in the body.

Explanation:

• Option A: The scenario focuses on body system interactions (nervous, endocrine, respiratory, circulatory) during exercise, not just exercise's general importance. Eliminate A.
• Option B: The problem describes sensory receptors (nervous system) detecting changes, sending signals, and triggering hormone release (endocrine system) to regulate functions. This shows hormones (from endocrine) and nerves (nervous) as signal molecules between systems (respiratory, circulatory, etc.). This matches the scenario.
• Option C: During exercise, increased heart rate and blood flow increase oxygen supply, not decrease. Eliminate C.
• Option D: The scenario emphasizes interaction between nervous and endocrine systems to regulate other systems, not nerves responding to every system (the focus is on the interaction for regulation, not nerve response to all systems). Eliminate D.

Answer:

B. Hormones act as signal molecules between all body systems.