Which two organ systems provide material required for the human body to produce atp

Explain how fossils scientists make discoveries about the lives of organisms and about how environments have changed over time. plz hurry up it time

What was dr. willem johan kolff’s first step in using the scientific process to invent the hemodialysis machine? he built the machine and tried it with various patients, collecting data about its effectiveness. when a patient’s kidneys failed, he wondered if it would be possible to perform kidney functions with an external machine. he researched and collected data about numerous patients who exhibited symptoms of kidney failure. he drew conclusions from studies of various symptoms of kidney failure, and drew a design for the ideal external blood-processing machine.

What causes darkening of the skin as melanin production increases