Final answer:
A poikilothermic organism would experience an increased metabolic rate as temperature rises within its tolerable range, requiring more energy intake. However, exceeding the upper temperature limits might lead to enzyme denaturation, reducing activity or triggering a protective torpor state.
Step-by-step explanation:
As a mobile, terrestrial poikilothermic organism experiences an increase in temperature from its lowest tolerance through its range of tolerable temperatures to the maximum it could tolerate, one would expect to see an increased metabolic rate. Poikilotherms are organisms whose body temperature varies with the temperature of their surroundings. The metabolic rate of these organisms commonly doubles to triples with a 10 °C raise in temperature, requiring more food for energy due to increased cellular respiration. However, if the temperature increases too much, beyond the tolerable limit, enzymes responsible for metabolic processes can become denatured, leading to decreased activity or inducing protective measures like torpor, hibernation, or aestivation to survive extreme conditions.