"I need to slice the cheese."
Translation:Мне надо нарезать сыр.
Here's a complexity of perfective/imperfective verbs. When you say that you need to slice the cheese you imply that it has to be cut in the end, while the action of you cutting it doesn't matter much. So, when you say "Мне надо резать сыр", you accentuate that the progress of cutting the cheese matters more than its outcome, while when you use a perfective form "нарезать", you basically mean that the cheese has to be cut after all. That's why the imperfective form would sound weird.
As an example of when "Мне надо резать сыр" would make sense: let's say a cheese-cutter (if there is such a job) is taking a break with friends. Now his break is over, so he gets up and tells everyone: "Well, I gotta go. I need to slice the cheese." This would be translated as "резать" because his job is a continuous process. This is certainly a very specific scenario though :)