The system of checks and balances was created so that one branch does not obtain more power and virtually "conquer" the government. It was created by our founding fathers when they realized that there first draft of an idea of government was not very easy to handle. Those were the Articles of Confederation which gave a few branches to much power over the people and government. In my opinion, the power of the branches is more or less fairly split.
Hope this helps!! Do good on your test/assignment