Then don't study that part.
The best way to study would be to make diagrams from memory, over and over, while checking your spelling every time. Also, try to verbally explain the cycle aloud to a friend in your class (or to anyone, I guess.)
Edited to add: It might help you in remembering the cycles if you know the meaning of the words you are using.
Bingo.
Forced recall (pulling it out of your memory starting with no information in front of you) is the best way to master the material. Every time you successfully pull a piece of information out of your brain it becomes both more firmly stored in your long term memory, and easier to recall it into your active memory when you need it.
If you have to know the spelling, that means your test won't have a word bank and the terms won't be in front of you. With this setup you will miss points if you don't have every term memorized, which leads me to two suggestions.
1. Count how many terms there are. Let's arbitrarily say it's 15 terms. Right when you sit down to take the test, write out the whole list of terms before you do anything else, on the back of the sheet of paper, or in the margins or wherever you have free space. Give yourself a word bank. If you know that there are 15 terms, you know when you have listed them all. You could also memorize them in "chunks," say 3 sets of 5 words at a time. Which leads me to my next suggestion.
2. To reiterate what was said by nuance, it would help you if you knew the meanings of the words. Things are easier to remember if they are associated with information that means something. Believe it or not, it is easier for your brain to organize and remember 10 new words
and their definitions than it is to just remember 10 nonsense words. This is one reason why people have a hard time remembering names...a name by itself doesn't have a meaning, it's just an arbitrary word that's difficult to integrate with the rest of the information in your brain that actually means something to you.
Also, if you know the meanings of the words it will make it much easier to put them in the proper sequence they follow in the life cycle.