in the stress response, is to corticotrophin-releasing hormone as is to adrenocorticotrophic hormone.

Hypothalamus; pituitary gland

Hypothalamix-pituitary-adrenal axis is a  complex set of direct influences and feedback interactions among the three organ components which are the hypothamus, pituitary gland and adrenal gland. These organ and their interactions forms the HPA axis  that controls the reaction to stress and regulates many body processes,including digestion, immune system mood and emotions

The answer to this will be from your lab notes/procedure. it would be best to ask another student who participated in the lab as we do not know what was done, what enzyme or if the temperature is celsius or fahrenheit. if i were to guess though i'd say the rate stopped due to enzyme denturing at high temperature

The hawk receives 0.1% energy from the caterpillar although the caterpillar gets eaten by another bird smaller than the hawk first