The answer to your question would be affect, I believe. I'm not 100% sure, but I hope this helps!
Turning in my essay late had a negative affect on my final grade.
Turning in my essay late had a negative effect on my final grade.
The difference between AFFECT and EFFECT are : Affect = to have an effect upon; make believe with the intent to decieve. Ex : Will the new rules affect me?... and Effect = A phenomonon that follows and is caused by some previous phenomonon; to produce.