Tag Archives: absorbance

Standard curve: A new test on maths4bioscience

A new test has been added to the maths4bioscience website – The Standard Curve.

So what is a “standard curve”?

A “standard curve” is a graph that is generated using known concentrations or amounts of something to produce a reading. The reading could be an absorbance, conductivity, fluorescence, pretty much anything that can be measured. The collected readings are then used to plot a graph of known amount or concentration against the thing that is being measured. This graph is a standard curve, which you can then use to determine the concentration or amount present in an unknown sample.

A very common type of “standard curve” is the protein determination standard curve. In this case, a range of known concentrations of a protein are used, and their absorbances are measured using a spectrophotometer. Plot the absorbances against the protein concentrations, and you have a standard curve. You cane now use the graph to determine the concentration of protein in a solution with a known absorbance.

Using data derived in the lab to plot a standard curve is a key skill for a bioscientist. And the new test allows you to practice your graph plotting and calculation of the unknown concentration of some protein samples.

So what is the “standard curve” test?

The test presents you with a table of data of absorbances for a range of known protein concentrations. You are also given the absorbances of three protein samples of unknown concentrations.


Using the data, you plot a standard curve. (If you have trouble drawing graphs then have a look at the blog post on How to draw a graph – there is also a graph drawing video on YouTube.)

Graph Drawing Checklist: Get a checklist for graph drawing – Send the Checklist


And using the standard curve you then determine the protein concentrations of the three unknowns.


Once you have determined the protein concentrations, and also calculated the extinction coefficient, you enter the data and click mark.

The site will then give you feedback on your answers, including showing you the standard curve for the data. If you get things right then all you see is the graph and the answers.


If you get any of the answers wrong then you still get the graph, plus an explanation of how to work out the correct answers.


Graph Drawing Checklist: Get a checklist for graph drawing – Send the Checklist


The data for the standard curve, along with the absorbances for the three unknowns, is randomly generated and so this means that the site can you provide you with countless questions for you to answer.

If you are struggling with your graph drawing, and getting good data plots, then you might like to take the free Maths and Chemistry Refresher Course we offer at Maths4Biosciences.

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