Introduction

The intent of the introduction is to show relevance for the study, give the necessary background information specific to the remainder of the report, and state the hypothesis or question to be answered

The introduction sets the stage for the rest of the study. It requires additional literature research to ensure the particular study is placed in the context of other studies. There are two basic parts:
A. Background information
B. Objectives of the study

It is important that the background information is presented prior to the objectives, so that the researcher can build up a case or a rationale that this study is important, before revealing the objectives. If the researcher is looking at a particular species, habitat, research method or experiment, the background information on these should be supplied. It is also important to sketch out the theoretical framework, so that other biologists could be convinced that this really is a worthwhile study. At the same time, avoid tangential details that only remotely relate to the study. All of this builds to the last sentence or so of the Introduction, when the researcher spells out the objectives.

As mentioned previously, literature must be included to bolster the Introduction. In fact, the introduction should be distilled down from multiple sources in order to produce a well refined and condensed presentation of the background information. Primary sources (peer-reviewed journal articles) are the ideal and preferred source used to uncover past research that has been done on your topic. Secondary sources such as textbooks do not always provide a specific a link to the original work, but they can be very useful for more basic, broad information that may not be contained within a journal article. Literature should be cited “in-text”; see the section “literature cited” for proper format. Finally, write your introduction in the present tense and never use first person pronouns such as ‘we’, ‘I’, ‘our’, ‘my’ etc.

Introductory sentence:
The first sentence in your introduction will begin with a generalized statement that entices your reader, but also points in the general direction of your report.

“If it weren’t for the activity of enzymes, life as we know it would not be possible. Enzymes play an important role in nearly every chemical reaction in our bodies through their activity as biological catalysts (Alberts et al., 2010)”

In the above example we get a sense that the writer got stuck in the big picture with no sense of direction.

“To maintain metabolic stability, organisms must have the capacity to catalyze chemical reactions efficiently and selectively throughout varying cellular conditions (Alberts et al., 2010)”

In a single sentence the second example not only hooks the audience but it also guides the reader in the direction of the introduction which would later include the following topics: 1) efficiency and specificity of enzymes and, 2) ability of enzymes to perform under varying conditions (perhaps of pH, temperature and inhibitors).

*The general introduction sentence will lead towards more specific introduction paragraphs and finally culminate to the purpose/hypothesis statement at the end

A. Background information (body)

The main body of the introduction should communicate specific topics that will be revealed within the results/discussion of your report. Continuing with the example of enzyme kinetics:

“The first way of characterizing the reaction will be to observe how the reaction proceeds under various pH’s to determine the optimal pH range in which the enzyme is most active. Each enzyme has a unique optimal pH at which its reaction rates are the highest (Marangoni, 2003; Mesentsev, 1997). As seen in the explanation of the reaction above, it is necessary for the dissociated hydrogen ions to be added or removed for oxidation and reduction to occur, therefore, the pH would affect the concentration of free hydrogen ions and say if the pH was too large, and the solution were basic, the solution would contain many hydroxide ions which would readily react with the hydrogen ions to form water and therefore removing some hydrogen ions needed for the reaction to occur (Mesentsev, 1997)”

There are a few things wrong with this paragraph, including a loss of direction, failure to communicate, and methodology descriptions which should be absent; remember to keep the introduction in present tense. Also, did you see the last sentence above? Be sure to prevent yourself from falling into the trap of redundancy and lose the flow of argument. The second example shows the same information presented in a logically with clear conclusions.

“The environment that an enzyme operates in greatly affects the activity of the enzyme. This activity decreases in the presence of too many or too few protons suggesting an optimum pH will provide the best environment for enzyme activity (Mesentsev, 1997). At a certain range outside this optimum pH an enzyme will denature and loose its structure and as a result lose its functionality (Nelson and Cox, 2008)”

In each of these examples there is a citation at the end of almost every sentence, this is completely acceptable and preferable. Also, do not get side tracked with ancillary information (e.g. if you are introducing enzyme reactions, do not include the chemical modifications that occur at each activation site, nor should you include the regulation system of the body that maintains proper environmental pH).

*A well written introduction will focus the reader to the topic presented in the objectives of the study

B. Objectives of the study

There are various ways of presenting the objectives of the study – basically it comes down to the underlying hypotheses or research questions. You will always include a purpose statement, but a hypothesis may or may not be required.

Purpose:
A purpose sentence should be the last sentence in your introduction and written in a list format:

“In this experiment, a spectrophotometric assays were used to (i) determine the optimum pH and,(ii) determine V0, Vmax, and Km for the enzyme alcohol dehydrogenase.”

Hypothesis:
If a hypothesis is required in the specific report instructions, this question should be the last sentence in your introduction. Make sure your hypothesis is a testable question and that it is written very specifically for the report. Here is an example of the process:
-Begin with an observation of an apparent difference between two things.

“Nitrogen levels in the pond appear to increase after the Salmon River floods the pond.”

-State the difference in a negative way in order to avoid bias in your observations.

“Nitrogen levels in the pond do not differ significantly when tested before and after Salmon River flooding events.”

This negative statement is called the null hypothesis and will not be proven/disproven, but rather credited or discredited according to the statistical test applied. Thus, there are two possible conclusions to draw from the null hypothesis; ‘reject’ the null hypothesis (discredit it through statistical tests), or ‘fail to reject’ the null hypothesis (credit the hypothesis through statistical tests).