Writing a biology lab report can seem daunting to those who have never written one. A lab report is different from a research paper or a creative essay; it follows its own rules and format. This playbook takes the guesswork out of writing this type of report.
A lab report has 7 parts:
A lab report will contain all of these sections (but some instructors may skip one or more, so remember to check), and will be written in a specific style. In the box below, click on the different tabs to see information about the style and sections of a lab report.
Lab reports follow a standard style (but always check with the course instructor, as s/he may choose to deviate from the standard). The two main components of that style are
These two components will be explained below.
"Concise" means "brief but comprehensive," that is, a lot of information is conveyed using a clear manner and straightforward style. Scientists like to get to the facts, so flowery language or too many words are frowned upon. See the example below.
Wordy: The lab was a bit chilly as our group walked in and so we turned the temperature up as we pulled the petri dish out of the refrigerator. We were surprised so many beetles had hatched. Upon counting the beetles, we saw that there were exactly 37.
Concise: Thirty-seven beetles were counted on the petri dish.
Lab reports normally use the passive voice, but students should check with the instructor, as some instructors do not make this mandatory. In the passive voice, the object of an action becomes the subject of the sentence.
Example of active voice: The scientist discovered a new planet.
Example of passive voice: A new planet was discovered by the scientist.
A. Which of the choices below is the best example of the kind of concise language that should be used in a lab report?
B. As part of an experiment, you placed a drop of blue dye in the middle of a Petri dish. Which of the choices below best describes this for a lab report?
The title of the lab report should be a brief summary of the main ideas included in the report.
Examples of good titles:
Examples of bad titles
Which of the titles below is the best for a lab report?
The abstract is a short summary (usually under 500 words) of the content of the report. An abstract includes
In the sample abstract below, objectives are in green, methods in purple, major results in red, and conclusions in blue. This abstract is 377 words long.
The objectives of this study were to determine the death rates of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes in three commercially manufactured full-fat ranch salad dressings, three reduced-fat ranch salad dressings, two full-fat blue cheese salad dressings, and two reduced-fat blue cheese salad dressings and to affirm the expectation that these dressings do not support the growth of these pathogens. The respective initial pH values of the four types of shelf-stable, dairy-based, pourable dressings were 2.87 to 3.72, 2.82 to 3.19, 3.08 to 3.87, and 2.83 to 3.49, respectively. Dressings were inoculated with low (2.4 to 2.5 log CFU/g) and high (5.3 to 5.9 log CFU/g) populations of separate five-strain mixtures of each pathogen and stored at 25 degrees C for up to 15 days. Regardless of the initial inoculum population, all test pathogens rapidly died in all salad dressings. Salmonella was undetectable by enrichment (<1 CFU/25-ml sample in three replicate trials) in all salad dressings within 1 day, and E. coli O157:H7 and L. monocytogenes were reduced to undetectable levels by enrichment between 1 and 8 days and 2 and 8 days, respectively. E. coli O157:H7 was not detected in 4 of the 10 salad dressings stored for 2 or more days and 9 of the 10 dressings stored for 6 or more days after inoculation. L. monocytogenes was detected in 9 of the 10 salad dressings stored for 3 days but in only one dressing, by enrichment, at 6 days, indicating that it had the highest tolerance among the three pathogens to the acidic environment imposed by the dressings. Overall, the type of dressing (i.e., ranch versus blue cheese) and level of fat in the dressings did not have a marked effect on the rate of inactivation of pathogens. Total counts and populations of lactic acid bacteria and yeasts and molds remained low or undetectable (<1.0 log CFU/ml) throughout the 15-day storage period. Based on these observations, shelf-stable, dairy-based, pourable ranch and blue cheese salad dressings manufactured by three companies and stored at 25 degrees C do not support the growth of Salmonella, E. coli O157:H7, and L. monocytogenes and should not be considered as potentially hazardous foods (time-temperature control for safety foods) as defined by the U.S. Food and Drug Administration Food Code.
The introduction of your lab report serves two purposes:  it stimulates your readers' interest and  it provides a general preview of what the rest of the report will cover.
The introduction is usually much longer than the abstract, and can vary from 3 to 4 paragraphs to a couple of pages. The length depends on several things, including the complexity of the topic and the experiment, and the length requirements given by the instructor.
How to organize the introduction
Note: leave out the procedures (those go in Methods), the results (those go in Results), and the conclusion (that goes in Discussion).
Annual vaccination is the most effective way to prevent the transmission of influenza. Yet, in recent years only about 40% of adults in the U.S. were vaccinated annually ("Recent Influenza Vaccination," 2013). A key challenge facing the public health community is to identify and implement effective and efficient strategies for improving influenza vaccination rates. One prominent approach is to increase access to vaccinations at non-medical, complementary settings such as retail settings and workplaces ("Adult Immunization," 2011; "Adult Immunization Programs," 2000).
While we have extensive data on the various locations where individuals seek vaccination and the importance of physicians’ offices as a source of counseling on vaccination (Uscher-Pines, Maurer, & Harris, 2011; "Place of Influenza Vaccination," 2010)], we have little information about how various settings are used by individuals with different vaccination habits (e.g., occasional vaccination vs. repeated, annual vaccination) and how preferred locations change as individuals become more accustomed to regular vaccination.
To address this gap, we used a large, nationally representative sample of U.S. adults to study the association between vaccination habits, based on self-reported experience with influenza vaccination, and vaccination location. Our investigation provides descriptive information about the potential roles that complementary settings play in promoting the initiation of vaccination among those who have never been vaccinated and in promoting the maintenance of previously established vaccination habits.
Explanation of the example
Example of Methods section
In preparing the catecholase extract, a potato was skinned, washed, and diced. 30.0 g of the diced potato and 150 ml of distilled water were added to a kitchen blender and blended for approximately two minutes. The resulting solution was filtered through four layers of cheese cloth. The extract was stored in a clean, capped container.
Four individually labeled spectrophotometer tubes were prepared using different amounts (as represented in Table 1) of the following reagents: a buffer of pH 7, a 0.1% catechol substrate, and distilled water. The wavelength of the Spectronic 20 spectrophotometer was set at 540 nm. To calibrate the specrophotometer at zero absorbance, a blank control tube prepared with no catechol substrate and labeled "tube 1" was inverted and inserted into the spectrophotometer.
Source: University of Richmond
You are writing a lab report about how to identify an unknown bacterial sample. Which of the following sentences is appropriately formatted for a Methods section?
Some bacteria are very harmful to humans, and so it is a good idea to figure out ways to recognize them.
The results section summarizes the findings of the study/experiment. The text in this section focuses on data, and uses graphs (called "figures" in lab report) and tables to illustrate the data, as well as a narrative description of the data. There should be no interpretation or analysis of the data -- that belongs in the discussion section.
Things to remember
Below, see an example for a figure (a graph), and a table. Notice the labels, units of measurement, and captions.
You conducted a study in which you taught basic Swedish words to kindergarten children. From the choices below, select the best caption for a graph in your lab report.
In the Results section you presented your findings without any interpretation or analysis. In the Discussion section you will interpret and analyze your findings and explain why they are important, what trends you noticed, whether the findings support your hypothesis, whether there are ways the experiment could be improved, or whether further research can be done on the topic or an aspect of the topic of your experiment.
DO NOT just present the results again -- examine why they are significant and important; that is, analyze and interpret the results.
Here is a paragraph from an article entitled "Why Do Female Callosobruchus maculatus kick their mates?" Notice that the researchers interpret their findings.
In this study we examined whether sexual conflict over mating duration exists in C. maculatus by exploring the fitness consequences of interrupting copulations at the onset of female kicking, assuming this indicates that females are approaching their optimal mating duration. We show that some female fitness components clearly benefit from longer copulations. While lifetime fecundity was unaffected by mating duration, both in singly and doubly mated females, uninterrupted copulations slightly increased longevity and resulted in 9% greater offspring numbers. This increase in offspring production is unlikely to be a consequence of sperm limitation in matings interrupted at the onset of kicking: sperm transfer occurs from the start of copulation, and sperm numbers far exceed the requirements for fertilisation . This effect thus appears driven by ejaculate properties associated with mating duration, potentially nutritional content. When mating was terminated at the onset of kicking, however, females had a greater propensity to remate.
From the choices below, which one would best fit in the Discussion section of a lab report?
The References section
The lab report should include in text and parenthetical citations in the body of the report, and a References list at the end of the report. At PVCC, the APA style of citing is used for lab reports. See the APA style playbook here. Citing is not difficult, but it can be tedious. Avoid using citation generators, because they always generate errors, and if you don't know how to cite, you will not notice them, and you will lose points for the errors.
In-text citations, parenthetical citations, and the References list
What is an in-text citation?
What is a parenthetical citation?
In-text/parenthetical citations and the References list
In-text and/or parenthetical citations must parallel the entries on the References list. She the examples below -- parallel elements are in maroon.
|Garber (2016) writes that "dark chocolate hasn't had a glass of Merlot since it saw Sideways" (para. 13).||
Garber, M. (2016). Milk chocolate is better than dark, the end. https://www.theatlantic.com/entertainment/archive/2016/10/milk-chocolate-is-better-than-dark-chocolate-the-end/505511/
|While chewing is normal and has health benefits for dogs, they need to be taught what they can chew and what they can't (ASPCA, n.d.).||
ASPCA. (n.d). Destructive chewing. https://www.aspca.org/pet-care/dog-care/common-dog-behavior-issues/destructive-chewing
|Duckworth (2018) writes that cadets with high scores are as likely to drop out of West Point as cadets with low scores.||Duckworth, A. (2018).. Grit: The power of passion and perseverance. Scribener.|