Seriously, don’t skip this step. If you read the directions right away, you are less likely to leave out mandatory parts of the lab report, you will be able to ask your instructor for clarification if necessary, and you can get set aside an amount of prep time appropriate to the scope of the project. Teaching assistants may also be able to provide guidance.
When reading the directions, be sure to make note of the due date(s). Depending on the assignment, there may be a single due date for a complete lab report or multiple due dates for different lab report components and/or drafts.
Your instructor has most likely provided you with information about the number and/or types of sources that should be cited in your lab report. For more information about finding the references used in a lab report, see Section B below.
Start by listing the required sections noted in the directions for the assignment. For the discussion section, also list the required topics (sources of error, future studies, etc.). Next, list the topics or even topic sentences for paragraphs in each section; in the results section be sure to note the locations for your figures and/or tables. If you haven’t created your figures and tables yet, sketch an outline of how they will be set up (axis labels for figures, column and row headings for tables).
Different writing guides will suggest different sections to start with – our suggestion is that you start with whichever section, in your opinion, will be easiest. As you write, focus on the big picture for each section before focusing on detail; that is, set up a logical flow of paragraphs before worrying too much about the specific wording in the paragraphs. For more information about writing style, see Section C. For detailed descriptions of the standard components of a lab report, see Section D. A sample lab report is provided in Section E.
Finish your lab report at least a few days early whenever possible. This will allow time for you to set it aside and review it with fresh eyes, and to hand it to friends and classmates so they can check for errors. Confirm that all of the required components listed in your directions are addressed in your lab report!
In most, if not all, of your lab reports you will have to put your work in the context of previous research – that is, you will have to discuss your work as it relates to research described in primary references. A primary reference is a peer-reviewed, original description of a research study. Typically this is a journal article describing original research. Since a several types of article are published in research journals (e.g. review articles or commentaries in addition to original research), you cannot assume that all articles published in journals will qualify as primary references. Since scientists must be able to reproduce each other’s work, a primary reference will always include a description of the research methods. Sometimes it will be obvious from an abstract that an article contains a description of original research (the research methods may be summarized); at other times you will not realize until you look at the full text if you have a primary reference or a secondary reference.
A secondary reference can also be very valuable in preparing your lab report, even though it will not count as one of your required primary references. Many journals publish review articles, for example, that give you an overview of a specific topic. The authors of a review article might summarize the results of a hundred or more individual studies in a given research area, while evaluating the merits and drawbacks of the different studies and putting the findings into context. Review articles can be invaluable when trying to learn about an unfamiliar area of research. Other examples of secondary references include textbooks, commentaries and magazine articles. A lab report will typically require use of at least one secondary reference in the Introduction.
Since it can take some time to find, read and decide if you can use references, it is critical that these sources be identified well in advance of the due date for your lab report.
A simple google search is unlikely to provide you with the references that you will need as you prepare your lab report. Your instructor may direct you to specific search resources or databases, but the two search resources most commonly used to find journal articles for biology courses are Google Scholar (http://scholar.google.com) and, for biomedical studies, PubMed (http://www.ncbi.nlm.nih.gov/pubmed). Effective use of these resources will require some judicious use of search terms. If you feel that your search terms are not yielding the types of articles that you are looking for, consult a research librarian, your instructor or your teaching assistant for assistance.
The biology libguide (http://mcla.libguides.com/biology) hosted by Freel Library contains a variety of search resources, including links to the online collections of journals housed in the Academic Search Premier and JSTOR databases. If you do your literature search through one of the links on the libguide (e.g. the Google Scholar link on the databases page http://library.mcla.edu/az.php), the articles freely available through the MCLA databases should appear as free full text in your search.
If you have a lot of relevant articles at your disposal, you can limit the articles retrieved in a PubMed search to those with free full text. In Google Scholar, free articles are usually indicated with links on the right-hand side of the screen. In most cases, however, the articles most relevant to your work will not be freely available. You have several options for obtaining these articles.
Depending on the instructor and the assignment, you may or may not be permitted to use websites as references. (Note that journal articles that are available in print but can be accessed online are considered to be journal articles, not websites, for reference and citation purposes). If you do intend to use a website as a reference, take care to evaluate it to determine if it is a suitable source. Is the website published by an institution or individual that would be widely accepted as a reliable and knowledgeable authority? If you have any doubt, check with your instructor. When obtaining information from websites, be sure to note the information that you will need for the reference list in your lab report (author, title, revision date or accession date, website; see an APA style guide, e.g. https://www.library.cornell.edu/research/citation/apa).
You can typically cite your textbook and/or lab manual as books in your lab report; other books may also be used for background information. These will not qualify as primary references. Articles from newspapers and magazines are not suitable resources for a lab report.
A complete review of suitable writing style will not be provided here. Resources that can help you to improve your writing style can be found under the “Writing Resources” tab of the Biology LibGuide (http://mcla.libguides.com/biology). The following are some of the issues and errors specifically encountered with lab reports in biology:
Scientific writing is concise, precise and professional. Words should be chosen with care to avoid vagueness (“we added 100 ml of water” rather than “we added some water”) and unnecessary detail (“the subjects ran up and down a flight of stairs for 5 minutes” rather than “the subjects, who were wearing workout clothes, were timed by an observer with a black electronic stopwatch as they ran up and down the stairs between the first and second floors in the science building from 11:00 to 11:05 am, for a total of 5 minutes”).
Contractions are typically avoided in scientific writing (“the fruit flies did not wake up from anesthesia” rather than “the fruit flies didn’t wake up from anesthesia”).
Quotes are not used in lab reports, and minor rewording to “paraphrase” is also inappropriate for scientific writing. For the most part you will be summarizing the key ideas in an article. If you paste a summary sentence from an abstract or a textbook then try to reword it, you will undoubtedly run into problems – in addition, the key point that the article’s authors were trying to make may not be the same point that you are trying to make. It is best even when making notes to summarize key points (citing the source) rather than copying sections of text. For more information, see the sections “Quoting, Paraphrasing and Summarizing” and “Taking Notes” in the “Citing and Documenting Sources” tab of the Biology Libguide (http://mcla.libguides.com/biology).
Verb tense will vary in a lab report. The present tense is used for descriptions of information that is widely accepted as true (or at least can be backed up by a published, peer-reviewed reference). Information that could be found in a textbook will always be written in the present tense (“yeasts are single-celled organisms”). The findings of published research studies are usually written in the present tense (“fruit flies are attracted to rotting bananas”), though a scientist’s actions in a published study are written in the past tense, for example: “Smith et al. (1978) observed that fruit flies were [or are, your choice] attracted to rotting bananas.”
The description of your own study, since it has not been published and accepted in the field, will be written in the past tense (“carbon dioxide accumulation was higher for plants kept in the dark,” “the bacteria were Gram-positive”).
There is no strong consensus in the field of Biology with regards to use of the active voice (“I did”) or the passive voice (“it was done”). Find out from your instructor if he or she will allow the active voice. If the active voice is acceptable, you may use “I” or “we” as the subject in sentences that describe your actions, though that should still be kept to a minimum. If the instructor prefers exclusive use of the passive voice, there should be no use of “I” or “we” in the document.
Significant has a very specific meaning in biology. If you say that there were significantly more brine shrimp on the light side of the tank, or that the plants kept in the dark were significantly smaller, that means you did a statistical analysis of your data and found a difference with a p value
Data is a plural (singular: datum). “Data were collected after 12, 24 and 48 hours.” “The data from this experiment support our hypothesis.”
Spell-check and grammar-check will not help you here – you must think consider your word choice every time you use “affect” or “effect” in your lab report. Affect is a verb (A is for Action); “the loud noises affected the behavior of the fish.” Effect is a noun; “different effects were observed with different chemicals.” Effect may, in rare cases, be used as a verb (= to bring about), but unless you are quite comfortable with this use, stick to the previous rules!
Biologists must be open to the possibility that ideas about how living things function will change based on new data. We therefore hate the word “prove,” since “prove” suggests that an answer is final. A single experiment doesn’t prove anything (particularly not a single, small-scale experiment conducted in a 3-hour lab block). Your data don’t prove or disprove your hypothesis – they can only support or not support your hypothesis.
Unless followed by a scientific unit, numbers under twenty should be spelled out in the text (fifteen leeches, 4°C, nine plants, 5 mL). If a number starts a sentence, it must always be written out, even if it is followed by a unit (sometimes it is easier to rearrange your sentence than to write out your number!)
The abbreviations for scientific units should be used; these need not (and should not) be spelled out at any point in the text. Use the degree symbol (°) rather than the word degree when describing temperatures – to find this, and to find the “±” for standard deviation and the “µ” for µL, click on the “Insert” tab in Word. Select “Symbol,” and then scroll through the options till you find the symbol that you need. Double-click on it or select “insert” from the bottom.
Some abbreviations are sufficiently standard that you do not need to define them in your lab report (DNA, RNA, mRNA). Other abbreviations must be defined at first use. (“The primary antibodies were dissolved in phosphate-buffered saline (PBS) at a ratio of 1:100. The secondary antibodies were dissolved in PBS at a ratio of 1:1000”). Minimize the use of abbreviations in your lab report – you are typically not restricted to a maximum number of words in a lab report, so make it as easy as possible for your reader to understand your text.
Chemical names (NaCl, H + ) do not need to be defined, nor do abbreviations for scientific units (mm, µL, min).
If you use specialized terms in your lab report that would not be familiar to most of your classmates, define or explain them in the text. (“The reduction in herbivory could be due to high levels of phenols, which are defensive chemicals made by plants.”)
Remember that genus and species names must always be written in italics (Hirudo medicinalis). After the first use of the genus name, it can be abbreviated (H. medicinalis). The species component of the name must start with a lower-case letter – note that auto-correct might try to make it a capital letter. When specifically referring to a kingdom, phylum, class, order or family for an organism, the name must be capitalized (“the medicinal leech Hirudo medicinalis belongs to phylum Annelida”), but if you are not using the official name, do not capitalize (“leeches are annelid worms”).
The following are the standard components used to describe a research study – you will find them in both lab reports and journal articles, though formats may vary somewhat.
The title will be a short, informative description of the experimental purpose, research question or research findings.
Rate of lactose digestion at different temperatures.
Dinoflagellate responses to increases in temperature.
Fruit flies are more attracted to apple cider than to apple juice.
For a lab report you, the writer, are the author. For group submissions there may be multiple authors. Your lab partners should also be acknowledged, if they contributed to the research. You can list lab partner(s) below or next to the author name(s).
For some assignments (e.g. drafts submitted for peer review), anonymous submissions will be required. Do not list the author or lab partners on these drafts!
Sample author list:
Author: Anne Goodwin
Lab Partners: Justin Golub, Sarah Herrick, Jerry Smosky
The abstract is a concise summary of the research study. This section should always be written last, so that you have the key points from each of the other sections to draw from. Include a sentence (at most, two sentences) addressing each of the following:
The salt content in water that plants take up can potentially affect plants growth and development in different ways. In this experiment, our group watered Brassica rapa plants with a 2% salt water solution from the time of planting to see what its effects would be on their growth and development. We planted eight seeds to be treated with the salt water and eight seeds that would be the control in normal tap water. There were five dependent variables that were recorded after four weeks of growth: stem height, total number of leaves, number of seed pods, number of flowers, and average leaf length per plant. Our results showed that the salt solution affected the total number of leaves that grew on each plant. These result showed that the plants were not as adversely affected by the salt solution as we had thought they would be.
In this lab, Drosophila melanogaster was used as a model to study development because of the wide range of research that has already been performed on this organism. In this experiment dissected and whole individuals were observed to examine physical characteristics including sex, larval body forms, imaginal discs, eggs, and polytene chromosomes. During the experiment we anesthetized flies and examined their body shapes and we dissected individuals to remove the imaginary discs and the polytene chromosomes within the salivary glands. Additionally, we observed larval forms and normal and dechorionated eggs. Based on the results of the lab we were able to recognize and understand the importance of the various life stages of Drosophila melanogaster as well as understanding the purpose of the structures involved in development.
The purpose of the introduction is to explain to the reader why it was important that you did your research study. The introduction will contain the following information:
The background portion of the introduction is typically two paragraphs in length. Citations must be provided for information that is not common knowledge; see the references section below for instructions for citing references.
Sample experimental purposes or research questions:
The purpose of this laboratory activity was to determine the rate of lactose digestion by lactase.
This led to the following research question: are fruit flies attracted to sugar?
We therefore wondered if temperature would change the behavior of leeches.
I hypothesized that leeches would be attracted to warm water.
The hypothesis was that fruit flies would be attracted to a solution containing sugar.
We predicted that heart rate would increase with exercise.
If fruit flies are attracted to sweet things, then fruit flies will be caught in greater numbers by a solution containing sugar.
Dinoflagellates are single-celled organisms that life in freshwater and saltwater environments. Some species live in symbiosis in corals, including the species Symbiodinium adriaticum, which is what our experiment is using. The experiment we are performing falls under the question of “How do changing ocean conditions affect dinoflagellates?” The oceans of the world are undergoing changes such as salt content and the increasing depths of the ocean from the melting polar ice caps. How will these factors affect marine life, including symbiotic dinoflagellates in corals? Costa et al studied the effects of seasonal dynamics in the coastal reefs off Picãozinho in Northeast Brazil and their effects on cell density and photosynthetic pigment contents of the zooxanthellae hosted by the dinoflagellate species Montastrea cavernosa (Costa et al, 2004). They found that cell numbers were greater in the rainy season, photosynthetic pigments were greater in the dry season, and that both parameters drastically dropped in amount during heavy rains. They speculated that this pattern is because of the rain cycles and how they affected the water clarity and the seasonal physiological condition of the cells (Costa et al, 2004).
Perhaps, when the water is clouded and murky, the dinoflagellates could not absorb enough light of their preferred spectrum to carry out photosynthesis, and therefore could not survive. Our group decided to test a similar aspect of water quality. We wanted to see if the color of the water, rather than the turbidity of the water, had any effect on dinoflagellate survival. Symbiodinium adriaticum have brown photosynthetic pigments, so we decided to color the water in the experimental flasks brown using food dye. This way, the water stayed clear, but it was a different color for light to pass through. In a natural setting, a change in water color could be due to an algae bloom or if a chemical got into the water that caused it to change color. An example of change in water color but not clarity in a contained ecosystem would be if you were treating a household aquarium with medicine containing Malachite Green to treat a fish parasite infection. It causes the water to turn a bright blue color, but doesn’t affect the clarity of the tank water. Our group hypothesized that water colored brown by food dye will have a negative effect on the growth of the S. adriaticum populations in the three test flasks.
The methods section is a critical component of a lab report or a published research study, as scientists must be able to reproduce each other’s work. Your methods section should be written in such a way that a classmate could reproduce your experiment based on the information provided. The methods section must be written in the past tense, using paragraphs rather than a list format. A separate list of materials is not included in biology lab reports; key materials are simply mentioned as they are used in the experimental setup and measurement procedures. Be sure to include the following information in the methods section:
We observed and collected data on populations of shaving brush algae in Little Lameshur Bay on the island of Saint John in the United States Virgin Islands. We counted algae over a one-quarter square meter area at multiple sites. We were able to locate three suitable seagrass beds each containing Manatee Grass and Turtle Grass. Within each seagrass bed, one group member positioned our quadrat at one-half meter intervals. At each of the seagrass beds, we placed the quadrat into each seagrass bed at the decided interval five times, giving us a total count of 15 observations. For each time we placed the quadrat down, we performed a visual count of the number of algae individuals, and then we photographed the site for later examination in order to prevent any miscounts. An analysis of variance was carried out to determine the difference between group means.
The results section will provide a written summary of your findings that can be understood independently from – and is complementary to – your figures and tables. Summarize your findings, citing each figure and table, and provide appropriate statistical descriptions (for example: means, standard deviations, p values, t statistics) as requested by your instructor. Note trends and observations, and be sure to use the word “significant” only in the statistical sense. Do not provide any interpretation of your results here (no opinons, no notes about the importance of the findings).
When describing differences between groups or trends in data, take care that your descriptions match your statistical analysis. For example, you cannot suggest that two groups are different if the p value for the comparison is > 0.05. (“Heart rates were not significantly different between the two groups. Heart rate was 80 ± 4 bpm for group A and 84 ± 3 bpm for group B, p=0.34.”)
The results section is usually quite short in a lab report. The results shown in each figure or table will typically be described in a single sentence (for a simple graph) up to, at most, a paragraph (for a complicated graph or table, or for observations). Again, do not forget to cite each figure and table as you describe the findings!
The SDS-PAGE procedure provided information to determine Rf values for the standard samples. The values vs. log molecular weight were plotted on an xy scatter plot to generate the protein standard curve (Figure 1). The slope of the line was used to calculate the molecular weights of the samples. Porcine pancreas was calculated to be 151.93 kDa, Bacillus licheniformis 141.82 kDa, and Aspergillus oryzae 141.82 kDa (Table 1).
Protein standard markers were used on the Western Blotting nitrocellulose paper to calibrate the molecular weight markers (Figure 2). The results from Western Blotting were the human salivary α-amylase band was present on the nitrocellulose paper however porcine pancreas, Bacillus licheniformis, and Aspergillus oryzae were non-reactive and did not exhibit colored bands (Figure 3).
Your data will be summarized in the text, but table and figures are essential in allowing the reader to interpret the results of your experiment or laboratory exercise. Care must be taken to design tables and figures to highlight data trends and key findings for the reader. Data tables and figures are considered part of the results section, and each table and figure must be cited in the results text; for example, “Heart rate increased after exercise, from 80 ± 4 bpm to 124 ± 9 bpm (p
Tables are particularly useful if you are providing descriptive observations, showing information for each of your research subjects, or if a variety of measurements were taken in your experiment. Graphs are most frequently used for comparisons and to show trends. Graphs, photographs and diagrams are all considered figures. Tables and figures that show subject characteristics or aspects of the experimental procedure are typically placed in the methods section; tables and figures that show experimental data are placed in the results section. Do not place tables and figures at the end of the document unless directed to do so by your instructor.
Sample decisions about how to present data
Heart rate and blood pressure (systolic and diastolic) are measured before and after exercise for ten subjects; you would like to draw attention to information for each individual subject in addition to showing average results for the group
You would like to show that the average heart rate after exercise is significantly higher than the average heart rate before exercise for your subjects.
Figure (bar graph)
You would like to show that the average heart rate decreases over time once exercise stops
Figure (line graph)
You would like to show a correlation between heart rate and systolic blood pressure after five minutes of exercise
Figure (scatter plot with trendline)
You would like to emphasize the distributions of heart rates for your subjects before and after exercise
Figure (box plots)
Table setup
Each table (and figure) will need a number and a descriptive title. The title of a table is positioned above the table, and any explanatory information is provided below the table. Since people typically read from left to right before up to down, it is best to place your subjects as rows and your data measures as columns. Each row should have a title, and each column should have a heading. If you are using human subjects, do not include their names in data tables (or anywhere else in the lab report).
Table 1: Molecular Weight and Rf Values for Standards and Samples.
Source
Molecular Weight
Rf Value
Log of MW