Question about metro 2033 and last light redux on Ps4 for those who own it?

I bought it a few days ago and playing 2033 currently, and I do you HAVE to increase your moral points in order to get the enlightened ending. I was trying to get trophies out of it. I know theres two choices at the end. I didn't do anything to affect my moral points, but I was going to beat it on Spartan mode and get the enlightened ending, then replay it on survival mode and get the ranger ending. Do I HAVE to increase my morality for a specific ending?