200-Level Biology Lab · Complete Reference for Students
Read this before your first lab and refer back to it throughout the semester. Each section below covers one part of your notebook entry: what belongs there, what good entries look like, and what will cost you points.
Your lab notebook is a scientific record, not a homework assignment. Real researchers keep notebooks because science must be reproducible, transparent, and honest. Treat your notebook as a document that a colleague could pick up and use to understand exactly what you did, what you found, and what you think it means.
Fall semester: Sections are critically graded in sequence — one section per lab, rotating through Title & Purpose (Lab 1), Background (Lab 2), Procedure (Lab 3), Results (Lab 4), Discussion (Lab 5), and Conclusion (Lab 6). All other sections that week are completion-graded.
Spring semester: All sections of every entry are critically graded.
Weekly completion grading counts toward your participation grade regardless of semester.
Permitted with disclosure: AI tools may be used to help you find background sources, check grammar, or understand an unfamiliar concept. If you use AI assistance anywhere in your notebook, note it — for example: “Used AI to locate sources for Background section.”
Not permitted: Using AI to generate or substantially draft any written section of your notebook — particularly the Background, Results interpretation, or Discussion — defeats the purpose of this course. Your Discussion must reflect your reasoning about your specific data. An AI has no idea what Figure 2 in your notebook shows or what prediction you wrote before lab.
How this is assessed: Strong AI-generated writing tends to be fluent but generic — it describes what enzymes do in general, not what your enzyme did in your experiment today. Grading specifically looks for direct reference to your data, your prediction, and your lab section’s results. Writing that could have been produced without running the experiment will not receive full credit regardless of how polished it is.
⚠️ Never delete anything. A lab notebook is a permanent record. If you misinterpreted data or made an error, do not remove the original entry.
Instead: add a dated correction [MM-DD-YY] in a new highlight color, and use strikethrough on the incorrect text to show it should not be used — but preserve it for the record.
The same rule applies to protocol changes: do not delete original instructions. Strike through what changed and note the modification in a different color font with your reason.
Critically graded: Lab 1 (Fall) · All entries (Spring)
Create a concise, descriptive title — do not copy the generic title from the protocol. A good title names the organism or system, the key variable or technique, and what is being determined.
✅ Do this: “Spectrophotometric quantification of protein concentration in cell lysates using Bradford assay”
❌ Not this: “Protein Lab” or “Lab 2: Bradford Assay”
State what you will do and why — in your own words, in 2–4 sentences. Strong purposes are specific enough that someone could tell your experiment apart from a different experiment in the same field.
Tip: Break long purposes into numbered Goals (Goal 1, Goal 2…) when the experiment has multiple distinct objectives. Each goal should name the technique and what it will achieve.
✅ Do this: “DNA will be extracted and purified from aquatic invertebrate tissue samples (Geneaid kit) for downstream PCR-based species identification. Goal 1: Extract genomic DNA. Goal 2: Purify and concentrate using the Zymo Clean & Concentrator. Goal 3: Assess quality and quantity by NanoDrop.”
❌ Not this: “The purpose of this lab is to learn about DNA extraction.”
Critically graded: Lab 2 (Fall) · All entries (Spring)
The Background explains why this experiment makes scientific sense — what a reader needs to know to understand what you did and what your results mean. It is not a summary of the pre-lab lecture, and it is not a copy of the protocol’s introduction.
Write from sources, not from lecture notes. Your Background should be grounded in cited sources (2 or more credible references). Summarizing what your instructor said in pre-lab is not sufficient — it does not demonstrate that you engaged with the scientific literature, and it produces generic writing that looks the same across the whole class.
AI note: This is the section most vulnerable to AI generation. AI-produced Background text tends to be accurate but generic — it describes the concept in general, not in the context of your specific experiment. Grading looks for your voice, your source choices, and your connection to what you actually did.
Critically graded: Lab 3 (Fall) · All entries (Spring)
Paste in the protocol procedure. Your notebook records what actually happened, not just what was planned. A reader should be able to reproduce your experiment from your Methods section alone.
✅ Do this: Strike through: “Add 200 µL buffer A.” — New color note: “400 µL buffer A used — original volume insufficient to cover sample [03-15-25]”
❌ Not this: Delete the original step and replace it, or add a note at the end with no indication of what changed.
Critically graded: Lab 4 (Fall) · All entries (Spring)
Results are observations and data only — no interpretation, no explanation of why. Save your analysis for the Discussion. A reader should be able to look at your Results section and form their own interpretation before reading yours.
Objectivity rule: If your sentence explains why a result occurred, it belongs in the Discussion, not here. Results state what was observed; Discussion explains what it means.
Critically graded: Lab 5 (Fall) · All entries (Spring) · Highest weight
Your Discussion is where you think in writing — not summarize what you did, and not repeat what was covered in pre-lab. A strong Discussion makes a scientific argument: it uses your specific results as evidence, evaluates whether they supported your prediction, and connects what you found to the biological concept at stake.
Every claim must be grounded in your data. Every figure and table in your Results must be referenced by number at least once.
A Discussion that could have been written before the experiment was run will not receive full credit.
1. Brief summary In 2–3 sentences, summarize what you did and what you found. This is your only summary — the rest of the Discussion moves forward from here. One sentence on purpose; one on the key result. Do not restate every procedural step.
2. Prediction evaluation (Required) Return to the prediction you wrote before lab. Was it supported or refuted by your results? Cite the specific figure or table number that confirms or contradicts your prediction and explain why. This question must be answered in every Discussion.
3. Biological concept connection [cite figures/tables] Interpret your results in terms of the biological concept this experiment was designed to investigate. Do not just name the concept — explain what your specific data tells you about how it works, or does not work, in this system.
4. Unexpected or notable results [cite figures/tables] Were there results that surprised you or did not fit the expected pattern? Provide a scientifically plausible explanation. If all results were as expected, explain why that outcome supports the underlying concept.
5. Error analysis Identify one specific source of error or limitation. Explain the direction it would likely push your results (overestimate, underestimate, or introduce variability) and why. “Human error” and “we may have made mistakes” are not acceptable answers.
6. Future directions Propose one specific improvement or follow-up experiment. Name the variable, condition, or technique you would change and what question it would answer.
✅ “Figure 1 shows enzyme activity peaked at 37°C, which supports my prediction that activity would decline above body temperature due to denaturation.”
❌ “The results showed what was expected based on the background information about enzymes.”
✅ “The unexpectedly low absorbance in Trial 3 (Table 2) may reflect incomplete mixing of the substrate, which would underestimate true reaction rate.”
❌ “There may have been human error during the experiment that affected our results.”
✅ “A follow-up experiment varying pH in 0.5-unit increments around the optimum would allow us to define the active site’s tolerance more precisely.”
❌ “In the future we could improve our technique and repeat the experiment more carefully.”
Critically graded: Lab 6 (Fall) · All entries (Spring)
The Conclusion is brief (5–8 sentences) and synthetic — it does not re-summarize the Discussion. Its purpose is to distill the single most important finding and its significance.
Common error: Conclusions that simply compress the Discussion add no value. A reader who has read your Discussion should gain new perspective from your Conclusion — a synthesis, not a repetition.
| Section | Belongs here | Does not belong here |
|---|---|---|
| Title & Purpose | Specific technique + organism + variable; numbered goals | Generic lab name; vague statements like “learn about DNA” |
| Background | Cited sources; mechanism explained; direct link to this experiment | Pre-lab lecture summary; copied protocol text; uncited claims |
| Procedure | What actually happened; actual volumes; strikethrough changes | Future tense; planned vs. actual values undifferentiated |
| Results | Data tables, graphs, calculations, stats — all labeled and numbered | Interpretation; explanations of why results occurred |
| Discussion | Reasoning from your data; prediction evaluation; error direction | Generic biology; pre-lab content; vague “human error” |
| Conclusion | Single key finding; hypothesis resolution; one forward question | A compressed re-summary of the Discussion |
This document is a reference, not a checklist. The goal is not to answer each prompt mechanically but to develop the habit of scientific thinking: making claims, citing evidence, and acknowledging uncertainty honestly.