This paper examined whether the vocabulary size of a text or its topic affects the overall text coverage of AWL words, and analyzed the frequency and text coverage of AWL words in research articles on biology written in English. It found that the number of AWL words occurring in a text may increase in proportion to its vocabulary size, but the overall AWL text coverage does not. It showed that the text coverage of the AWL words accounted for around 8.46% in 60 research articles on biology written by Koreans and published in Korea, which was a little bit lower than the coverage ratio of around 9.56% observed in the data of the same number of research articles on biology, published in English speaking societies. This paper also identified some 24 academic word families which were not used at all in 120 research papers, and therefore whose usefulness in biology literature are in doubt. It further suggested that a new academic word list should be developed for students of biology.