CCEA A-Level Life and Health Sciences 0008
Experimental Techniques
Human Body Systems
Physical Chemistry in Industrial Processes
Brain ScienceDouble Award
Material ScienceDouble Award
Medicine, Drugs and Clinical TrialsDouble Award
Scientific Method, Investigation, Analysis and Evaluation
Organic Chemistry
Medical PhysicsA2 option
Sound and LightA2 option
Genetics, Stem Cell Research and CloningA2 option
MicrobiologyDouble Award
Oral Health and DentistryDouble Award
Histology and PathologyDouble Award
Analytical Chemistry TechniquesDouble Award
Enabling TechnologyDouble Award
Experimental Techniques
Biological tests, colorimetry, chromatography and osmosis
- 3 things to know
- AS 1
Overview
Tests for starch, reducing sugars, protein and lipids, colorimeters, blanks and calibration curves, amino acid chromatography with ninhydrin and Rf values, and osmosis in potato cylinders.
What you need to know
Answer each one before you reveal it.
How is starch identified in a food sample?
How are reducing sugars identified?
Questions from this subtopic
Each one with the model answer underneath.
- 1
How is starch identified in a food sample?
Model answer
Iodine solution is added to the sample. A colour change from orange-brown to blue-black shows starch is present.
- 2
How are reducing sugars identified?
Model answer
Benedict's reagent is added and the mixture heated in a water bath. A colour change from blue through green and yellow to brick-red shows reducing sugar.
- 3
How is protein identified?
Model answer
Biuret reagent is added to the sample. A colour change from blue to lilac or purple shows protein is present.
- 4
How are lipids identified?
Model answer
The sample is shaken with ethanol and then poured into water. A cloudy white emulsion shows lipids are present.
- 5
What is a colorimeter?
Model answer
A colorimeter measures how much light of a chosen colour passes through a coloured solution. The reading is given as absorbance or transmission.
- 6
What is a calibration curve?
Model answer
A calibration curve plots colorimeter readings for solutions of known concentration. The concentration of an unknown sample is read from the curve.
Other ways to work this
The same content, four other ways.
What is inside Levo
Six ways to work the same material.
Every question in Experimental Techniques, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
Or £46 a year, about £3.83 a month. Cancel anytime.