Cells use oxygen to assist in cellular respiration. This type of respiration, called aerobic cellular respiration, converts stored energy into a usable form. The first stage of aerobic cellular respiration, glycolysis, can be performed without oxygen.
A persuasive speech is a specific type of speech in which the speaker has a goal of convincing the audience to accept his or her point of view. The speech is arranged in such a way as to hopefully cause the audience to accept all or part of the expressed view.
In linguistics, an utterance is a unit of speech. In phonetic terms, an utterance is a stretch of spoken language that is preceded by silence and followed by silence or a change of speaker. (Phonemes, morphemes, and words are all considered segments of the stream of speech sounds that constitute an utterance.)