2.1.a Carry out tests for reducing sugars and non-reducing sugars, the iodine in potassium iodide solution test for starch, the emulsion test for lipids and the Biuret test for proteins to identify the contents of solutions.
2.1.b Carry out a semi-quantitative Benedict’s test on a reducing sugar using dilution, standardising the test and using the results (colour standards or time to first colour change) to estimate the concentration.
Doing biochemical testing is important to identify the presence of specific biological molecules in biological samples.
The above table summarises the tests that can be used to identify the presence of reducing/non-reducing sugars, starch, lipids, and proteins.
⚠️Note:
- Reducing sugars include all monosaccharides, such as glucose, and some disaccharides, such as maltose.
- Some disaccharides, such as sucrose, are not reducing sugars.
- When you do a Benedict’s test and you do not see a colour change, then you should test for non-reducing sugars.
🧠📝It is important to remember the results column from the above table, as a question about it may come up in your GCE CIE Biology exam.
Nicely done! See you next time! 🙌
References:
Jones, M., & Parkin, M. (2018). Cambridge International AS and A Level Biology. Cambridge: Cambridge University Press.