<p>I dont think you need to memorize words.However there will be a minumum requirement which need to be met.And if you can make out the meaning from the context its enough.
root words help a lot in improving vocabulary.If you want to improve your score in verbal section this link will help you .having good vocabulary is not a waste can use it any way.
[Vocabulary</a> Builder Home](<a href=“http://www.vocabularybuilder.info/]Vocabulary”>http://www.vocabularybuilder.info/)</p>