The relationship between surface area-to-volume ratio and metabolic rate is crucial in biology. Smaller organisms tend to have a higher surface area-to-volume ratio, which facilitates faster rates of gas exchange, nutrient absorption, and waste elimination, leading to higher metabolic activity. In contrast, larger organisms have a lower ratio, requiring more energy to maintain their metabolic processes. This physiological principle helps explain why smaller species often have higher heart rates and quicker metabolic rates compared to larger ones, influencing their overall energetic needs and evolutionary strategies.