The human body requires a nearly constant inflow of food, water, and oxygen to remain alive. as a whole, the human body is an example of a

The human body is a complex structure made up of a number of organ system harmoniously working together to keep it living. All these organ systems are related to one other and requires food, oxygen, and water to remain alive. The constant flow of these essential requirements of human body is essential for it's survival. This makes the human body a perfect example of a machine.

Hence, the answer is machine.

enzyme speed up the reactions