Passage keywords are a special type of specific question. Not all specific questions will reference a line number. Some specific questions will mention a subject discussed in one specific part of the passage. You will need to be able to find this relevant keyword within the passage quickly, so that you can read the appropriate section of the passage and answer the question.
You should have a few different tools are your disposal to help you quickly find the specific keyword mentioned in the question. First, if you read the passage actively, you may have a note in the margin that uses the keyword. You should then able to jump right into that paragraph to answer the question. If you did the Preview Process, you should have a general idea of what each paragraph is about, so you should be able to start looking at the appropriate section of the passage to find that keyword.
You can also consider where you are in the questions to hep you to find that specific keyword. The questions usually begin with the beginning of the passage and work their way towards the end of the passage: for example, question 1 might ask about lines 4-6; question 3 about 10-12; and question 5 about line 16. Armed with this information, you can use your place in the questions to help you decide where to start scanning for the keyword. If question 1 asks about lines 4-6, question 2 is a "keyword question" and question 3 asks about lines 11-12, then you probably want to start skimming the passage between lines 6 and 11 to try to find the keyword mentioned in question 2.