Final answer:
Two different enzymes are needed for the synthesis of glycogen from glucose phosphate because of substrate specificity, to increase reaction speed, and due to pH requirements.
Step-by-step explanation:
Two different enzymes are needed for the synthesis of glycogen from glucose phosphate for several reasons. First, the enzymes provide substrate specificity, meaning they only bind to and work with specific molecules. This specificity allows for the selective synthesis of glycogen from glucose phosphate. Second, the enzymes help to increase the reaction speed, as each enzyme is optimized to work efficiently in its specific step of the synthesis process. Finally, the enzymes may have different pH requirements for proper functioning, which is why different enzymes are needed for different steps of the synthesis process.