Unnecessary background
If you state facts or describe mechanisms, do so in order to make a point or to help interpret results, and do refer to the present study. If you find yourself writing everything you know about the subject, you are wasting your time (and that of your reader). Stick to the appropriate point, and include a reference to your source of background information if you feel that it is important.
Including material that is inappropriate for the readership
It isn't necessary to tell fellow scientists that your study is pertinent to the field of biochemistry. Your readers can figure out to what field(s) your work applies. You need not define terms that are well known to the intended readership. For example, do you really think it is necessary to define systolic blood pressure if your readership consists of physicians or cardiovascular physiologists?
Subjectivity and use of superlatives
Technical writing differs from the writing of fiction, opinion pieces, scholarly English papers, etc. in many ways. One way is in the use of superlatives and subjective statements in order to emphasize a point. We simply do not use such writing styles in science. Objectivity is absolutely essential.
Subjectivity refers to feelings, opinions, etc. For example, in your discussion you might write, "We felt that the fixative was bad, because we had difficulty finding flagella on our Chlamydomonas." Another researcher is unlikely to risk time and resources on the basis of your "feeling." On the other hand, you might write, "The percentage of cells with flagella was inversely proportional to the time they spent in fixative, suggesting that the fixative was causing cells to shed flagella." This is information that another scientist can use.
Superlatives include adjectives such as "huge," "incredible," "wonderful," "exciting," etc. For example, "the mitochondria showed an incredibly large increase in oxygen consumption when we added uncoupling agent." Your definition of incredible might be different from that of someone else - perhaps a five fold increase is incredible to you, but not for the next person. It is much better to use an objective expression, such as "Oxygen consumption was five fold greater in the presence of