What you need to know
- Unit 6Tabulate data with appropriate units, use correct units throughout, and calculate with a suitable number of significant figures.
Graph plotting, including a logarithmic axis, is the next lesson. Illustrative numbers are not experimental results. Statistical tests are not required in order to finish a table.
By the end, you should be able to…
- Put the independent variable first and the unit in each heading.
- Keep raw readings visible beside any mean or rate.
- Process a short table without adding precision.
Build your understanding
Headings carry the quantity and the unit
Each column needs a heading. The unit sits in the heading, not beside every number. An illustrative heading is “light intensityThe amount of light energy reaching a given area in a given time. / arbitrary units” or “Volume of gas / cm³”. The independent variable usually goes in the first column, in the order it was changed.
“Amount” is too vague. A rate needs a compound unit, such as cm³ min⁻¹. If you calculated a logarithm, the heading has to say so, for example “log₁₀(number of bacteria)”, because those numbers are not the counts themselves.
Raw, then processed
Repeats need their own columns or clearly separated entries. The mean is a further column. Do not overwrite a raw value with the mean. An inconsistent reading can stay visible and stay out of the mean only if you say that it was checked.
Illustrative masses 1.8 g, 2.0 g and 2.2 g have the mean (1.8 + 2.0 + 2.2) ÷ 3 = 6.0 ÷ 3 = 2.0 g. Write 2.0 g, not 2.000 g. A later rate column must state its formula. Do not invent a rate the question did not define.
The calculation does not earn new digits
Use the same decimal places down a column from the same instrument. Mixing 2, 2.0 and 2.00 implies three resolutions. A percentage or a mean can have a stated rounding rule, but it should not grow a tail of digits.
Units have to survive the calculation. A density of 48 plants per m² is not 48 plants. If two columns use different units, convert before you subtract or divide, and show the conversion. A table that is clear enough to check is the table Unit 6 is asking for.
| Temperature / °C | Mass 1 / g | Mass 2 / g | Mean mass / g |
|---|---|---|---|
| 10 | 1.8 | 2.2 | 2.0 |
| 20 | 1.4 | 1.6 | 1.5 |
| 30 | 0.9 | 2.4 | check 2.4 before you average; do not hide it |
Graph skills: SLAPUK and choosing a scaleTable headings with units become the axis labels.
Make your reasoning visible
Unit in the heading
If a cell needs its own unit, the column is muddled. Split it or convert it.
The column you were asked for
If the question says calculate the mean, show the mean. If it says calculate the rate, add a rate column and the formula.
Avoid this misconception
The claim: The mean replaces the repeats, so the raw numbers can be rubbed out.
The correction: The raw numbers are the evidence for the mean and for any value you query. Keep them beside the processed column.
Check your understanding
Try each question before opening the suggested answer.
Practice question
Retrieval and explanation · suggested answer
Illustrative masses are 1.8 g, 2.0 g and 2.2 g. Calculate the mean and say how to write it.
Show suggested answer
(1.8 + 2.0 + 2.2) ÷ 3 = 2.0 g. Write 2.0 g so the decimal places match the readings. Do not write 2.000 g.
Practice question
Retrieval and explanation · suggested answer
A student heads a column “log number” and writes 3.00, 3.30 and 3.60. Why might a reader still misread it?
Show suggested answer
The heading should say the base, such as log₁₀ of the count, and what the original number was. Otherwise 3.30 can be mistaken for 3.30 organisms rather than a logarithm.
Practice question
Retrieval and explanation · suggested answer
Why is the independent variable placed in the first column?
Show suggested answer
The table is then read in the order the factor was changed, which is also the usual order for plotting that factor on the x-axis. The outcome columns stay as the measurements.
Take the idea further
Apply the same specification knowledge to an unfamiliar problem. Any extra assumptions are supplied in the question.
Stretch question
An unfamiliar table gives juice titres of 6.5, 6.7 and 11.2 cm³ against the same volume of DCPIP. Calculate the mean you would use after a decision about 11.2 cm³, and say what a smaller mean titre would mean for vitamin C. The numbers are illustrative.
Show a hint
Decide whether 11.2 cm³ belongs with 6.5 and 6.7 before you average.
Explore the reasoning
6.5 and 6.7 cm³ agree. 11.2 cm³ is inconsistent and should be checked or repeated. If it is excluded after that check, the mean is (6.5 + 6.7) ÷ 2 = 6.6 cm³. A smaller titre means a higher vitamin C concentration when the DCPIP is the same. The assumption is that 11.2 cm³ was checked and not reproduced. Do not call the difference significant.
Recall this lesson
Lesson recall questions
Question 1 of 5: State where units should appear when tabulating mean rate of photosynthesis in cm³ min⁻¹ against light intensity in lux.
Unit 6 analysis
Practice question
Retrieval and explanation · suggested answer
State where units should appear when tabulating mean rate of photosynthesis in cm³ min⁻¹ against light intensity in lux.
Lesson: A1: Tables, units and processed numbers
Try this from memory first.
Put your biology to work
Explore where these ideas appear in the world. Enrichment, not extra required recall.
The unit is part of the result
A1 · Tables, units and processed numbersThe organisations that maintain the SI treat the unit as part of how a quantity is stated. In a school table the same rule is practical: a heading…Specification Unit 6 · AnalysisRead & use the scienceClose article
Why this matters
The organisations that maintain the SI treat the unit as part of how a quantity is stated. In a school table the same rule is practical: a heading without a unit, or a processed number that has lost its unit, is unfinished even when the arithmetic is right. In a shared research dataset, a column heading is part of the measurement record. Without a unit or definition, another laboratory cannot distinguish raw observations from calculated rates. Keeping repeats visible lets a reader see scatter rather than only a polished mean. The same habit helps in Unit 6: put units in headings, separate raw and processed values and use enough significant figures to make the calculation checkable.
Back to the specification
Pearson Edexcel IAL Biology · Issue 2, February 2021 · Unit 6, pp. 39–42. The application extends beyond required recall.
- Unit 6 · Analysis Tabulate, calculate, graph and interpret data, including possible logarithmic scales, gradients, uncertainty and realistic modifications.
Use the science
A mean is calculated correctly as 2.0 but the column has no unit. Is the processing finished?
Explore a possible response
No. 2.0 g and 2.0 kg are different results. The unit has to stay with the processed number, usually in the heading.
Explore the source
A reusable table needs a readable method
A1 · Tables, units and processed numbersThe FAIR principles aim to make research data findable, accessible under appropriate conditions, interoperable and reusable. A biology table can be numerically correct yet difficult to reuse if…Specification Unit 6 · AnalysisRead & use the scienceClose article
Why this matters
The FAIR principles aim to make research data findable, accessible under appropriate conditions, interoperable and reusable. A biology table can be numerically correct yet difficult to reuse if it lacks units, definitions, replicate identifiers or the method used to calculate rates. This extends Unit 6 analysis: separate raw readings from processed results so a reader can reconstruct the calculation. FAIR does not mean posting participant data publicly; access can be restricted where privacy requires it. The practical lesson is that a table should travel with enough context to remain meaningful.
Back to the specification
Pearson Edexcel IAL Biology · Issue 2, February 2021 · Unit 6, pp. 39–42. The application extends beyond required recall.
- Unit 6 · Analysis Tabulate, calculate, graph and interpret data, including possible logarithmic scales, gradients, uncertainty and realistic modifications.
Use the science
Why is a column headed only “rate = 3.2” unsuitable for a shared respiration dataset?
Explore a possible response
It lacks the quantity definition and units, such as cm³ O₂ g⁻¹ min⁻¹, plus the method and replicate. Another reader cannot compare or reproduce the value reliably.
Explore the source
- FAIR guiding principles for scientific data managementPeer-reviewed research (PMC)