Biology Pratical Work
- Created by: Vss2017
- Created on: 24-11-17 10:10
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- Biology Pratical Work
- Qualitative tests
- Benedict's Test- used to detect Reducing sugars
- Heated in a water bath, wiht Benedict's Solution
- blue, green, yellow, orange, brick red precipitate.
- Non-reducing suagrs
- 1.Negative result with benedict's
- 2. Hydrolise sample by heating with Dilute Hydrochloric Acid in a water bath.
- 3. Once cooled Neutrilise with Sodium Hydrogencarbonate
- 4. Test with benedict's solution- Positive test
- 3. Once cooled Neutrilise with Sodium Hydrogencarbonate
- 2. Hydrolise sample by heating with Dilute Hydrochloric Acid in a water bath.
- 1.Negative result with benedict's
- Heated in a water bath, wiht Benedict's Solution
- Iodine test- starch
- yellow- brown to blue-black
- Glucose-Specific tests
- Cllinistix strips change colour in glucose only
- used to test for the presence of glucose in urine which is a symptom of diabetes
- Biuret Test- detects the presence of peptide links in PROTEIN
- adding equal volumes of sodium hydroxide solution then testing wiht a few drops of dilute copper sulfate solution
- shake gently
- blue to lilac if protein is present
- shake gently
- adding equal volumes of sodium hydroxide solution then testing wiht a few drops of dilute copper sulfate solution
- Benedict's Test- used to detect Reducing sugars
- Identifying amino acids through the use of chromotography paper
- preparing the chromatogram
- chromatogram cut to fit the tank. allowed to attach to the lid and drop to just above the base of the tank
- horizontial line drawn in pencil. BASE LINE
- Solution containing amino acids needs to be SPOTTED onto the pencil line using a MICRO-PIPETTE.After each drp the solution is DRIEDout before process is REPEATEDto increase CONCENTRATION
- Avoid contmination1. hold chomatogram at the edges2.dont set on lab benches- range of other chemicals could contaminate.
- before placing the prepared chromatogram into the tank, the solvent should be added and the lip placed on top to allow the stmosphere to become saturated.
- Running the chromatogram
- 1.ensure the base line does not make contact with the solvent- suspended above2.securely attached to the lid3.not suspended at an angle
- developing the chromatogram
- Mark the solvent front wiht a pencil.spray chromatogram with NINHYDRIN in a fume cupboard
- After being re-dried the amino acids appear as purple spots.The spots should be encircled wiht a pencil as they will fade
- Calculating the Rf value
- The distance moved by the solute (amino acid) X divided by the distance moved by the solvent front Y.
- measuring the distance from the origin to the position of the solvent front. and hen from the origin to the position of the amino acids.
- Rf value is always less than 1.Rf value = X/Y
- The distance moved by the solute (amino acid) X divided by the distance moved by the solvent front Y.
- preparing the chromatogram
- Qualitative tests
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