No need to cram for anything. Just describe the beer in front of you. Now saying “fruity” don’t cut it, describe the fruits you perceive. If you cannot put your finger on the fruit, describe something that has that same aroma or flavor. So if the aroma is dirty toilet, put that down. So what if you cannot remember the exact bacterium which causes the smell, the exam doesn’t care, simply that you perceived the smell is enough to do well. Also don’t make stuff up or try to tell how something is or isn’t to style until the Overall Impression section. You will generally be incorrect if you do.
So relax, describe the beer fully and once completed find any major flaw and use that to answer how the beer could be improved. Simple!