Being responsible for the organization's procurement activities means the Purchasing Manager oversees the procurement process and ensures that procurement decisions align with the organization’s needs and policies. Additionally, being responsible for the performance of supplier contracts indicates that the Purchasing Manager monitors and manages supplier relationships and ensures that suppliers meet their contractual obligations. These responsibilities make the Purchasing Manager well-suited to be appointed as a Senior Supplier, as they have a significant influence on supplier selection, contract performance, and procurement strategy, which are crucial for the project's success.