How do I know if my Mac Pro is 32 or 64 bit system?

How to tell if your Intel-based Mac has a 32-bit or 64-bit processor - Apple Support

For future reference, all new MACs are now 64 bit. All Macs with Processor names like: Intel Core i* , where * is a number are 64bit.

Also, Intel Macs that have the number "2" between "Intel Core" and "Duo" are 64-bit. The earliest MacBook Pros had Intel Core Duo processors (no "2" in the name) and they are 32-bit as other have stated repeatedly.

Yup.

Thank you!