Final answer:
The punctuation should be placed between 'to become a zoologist' and 'it all paid off' to separate the two independent clauses in the sentence.
Step-by-step explanation:
The punctuation in the sentence 'Jamice had worked for years to become a zoologist it all paid off when she held her first baby tiger.' should be placed between 'to become a zoologist' and 'it all paid off' to fix the run-on sentence. By adding a period, semicolon, or a coordinating conjunction followed by a comma, you separate the two independent clauses, making the sentence grammatically correct.
For example: 'Jamice had worked for years to become a zoologist. It all paid off when she held her first baby tiger.' Or, using a semicolon: 'Jamice had worked for years to become a zoologist; it all paid off when she held her first baby tiger.'