Biology 2.1.2 Quantitative methods Flashcards
What is colorimetry?
A quantitative method used to determine the concentration of a chemical substance in a solution by measuring the absorbance of light.
How does a biosensor work?
A biosensor detects specific biological molecules using a biological components, converting the interaction into a visible, quantitative or qualitative, measurable signal e.g. a colour or a reading,.
What is the Rf value in chromatography?
Rf (retention factor) is calculated as:
* Rf = distance moved by solute / distance moved by solvent
What is the purpose of chromatography?
To separate and analyze complex mixtures of biological molecules, such as proteins, carbohydrates, vitamins, and nucleic acids.
How is paper chromatography set up?
A spot of the sample is placed on chromatography paper, which is then placed in a solvent that travels up the paper, separating the components based on their solubility.
What is thin layer chromatography (TLC)?
TLC involves a stationary phase (thin layer of chromatogrraphy paper ) and a mobile phase (solvent), allowing for the separation of compounds based on their different attraction for the phases.
Substances attracted to the paper: Move slowly and travel a short distance
Substances attracted to the solvent: Move quickly and travel further
What types of molecules can be separated using chromatography?
Proteins, carbohydrates, vitamins, and nucleic acids can all be separated and analyzed using paper or thin layer chromatography.
Describe a practical investigation using chromatography.
To analyze a mixture of amino acids, perform paper chromatography by applying the mixture to the paper, running it in a solvent, and calculating Rf values for each amino acid to identify them.
What factors affect the separation in chromatography?
Factors include:
* Choice of solvent
* Nature of the stationary phase
* Size and polarity of the molecules
* Temperature during the process
How can colorimetry be applied in biological research?
Colorimetry can be used to determine the concentration of glucose in a solution.
Outline how colorimetry can be used to determine the glucose concentration of a solution
- Use a filter in the colorimeter
- Calibrate the colorimeter with distilled water
- Perform the benedict’s test on known concentrations of glucose.
- Measure the transmission of light of each solution using a colorimeter.
- Plot a calibration curve.
- Repeat with unknown glucose solution, use the curve to find it’s concentration
Why must a filter be used for a colorimeter?
To maximise the absorbance of light by the solution
Why must a colorimeter be calibrated using distilled water?
Distilled water has an transmission of light of 100%.
