De que manera la ciencia política ayuda a comprender los fenómenos sociales

In at least two paragraphs, discuss the differences between the principles of republicanism and democracy. explain whether you think the united states is more of a republic or a democracy. refer to at least one example from the constitution

How has congress added to the president’s role as chief economic planner over the years?

This is for my social studies guide and i can answer 21/22 of it perfectly fine. but can someone tell me what the caste system was, and what divisions/classes that it was apart of it?