Enzymes are proteins that speed up the body's chemical reactions. They require a constant temperature to work at their optimum. Just like other proteins, the enzymes denature at extremely high temperatures.

Heat stroke is an uncontrolled increase in body temperature. Exposure to very hot temperatures produces increased sweating, and can produce dehydration, which may lead to reduced sweating and further increase of core body temperature.

Hypothermia is the condition wherein the body temperature drops faster that the body regains heat. This usually occurs when the body is at the temperature below 35 ^oC. When this happens, the enzymes denature. Thus, the biological processes of the organ systems will fail to work properly until they shut down. This further leads to death of the individual.

Correct Answer: (4) release of insulin

Insulin is one of the antagonistic hormones that regulate the concentration of glucose in the blood. If the blood glucose level rises over 90ml/100mL in humans, the pancreas secretes insulin to trigger its target cells to take up the excess glucose from the blood.

Correct Answer: (2) Homeostasis

Homeostasis is the maintenance of a constant environment (i.e. temperature, water levels, glucose concentrations) in the body. Example of this is vasodilation wherein the capillaries expand to bring blood closer to the surface of the skin to cope up with the increase of temperature brought about by strenuous exercise.

Synthesis, excretion, and locomotion are not the reasons why vasodilation occurs.