An Immediate Source of Energy for Exercising Muscle Cells Is

Question

An immediate source of energy for exercising muscle cells is _____.  
A) creatine phosphate
B) aerobic respiration
C) anaerobic respiration
D) fermentation
E) glycolysis

Accepted Answer

Creatine phosphate is a molecule that can quickly donate a phosphate to ADP to quickly produce ATP, providing an immediate source of energy for exercising muscle cells. Aerobic respiration requires oxygen and takes time to produce ATP, while anaerobic respiration and fermentation produce ATP without oxygen but are less efficient and cannot sustain exercise for long periods of time. Glycolysis also produces ATP but is not an immediate source and requires further processing.