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level: Testing for Biological Molecules

Questions and Answers List

level questions: Testing for Biological Molecules

QuestionAnswer
What are the Different Stages, or Colours of Benedict's Reagent?[No Sugars] Blue-->Green-->Yellow-->Orange-->Brick Red [Lots of Sugar]
How can you Test for Reducing Sugars?-First, add Benedict's Reagent to the Sample and then Heat it up to 75 Degrees -If Positive, then a Coloured Precipitate will Form which will Determine how much Sugar is in the Solution. Red= Lots of Sugar while Green = Little Sugar.
How can you Test for Non-Reducing Sugars?-First, add Hydrochloric Acid to your Test Solution, followed with a Temperature Rise of 75 Degrees, then Finally adding Sodium-Hydrogen-Carbonate to Neutralise it -Then, carry out Benedict's Test [Add the Sample simply] -If the Solution is Blue - No Sugars -If the Solution has a Coloured Precipitate, Non-Reducing Sugars is Present
What is the Difference between Reducing Sugars and Non-Reducing Sugars?-REDUCING Sugars are just Simple Sugars made from ONE Unit, like Glucose, or a FEW MADE from Units joining Together, like Maltose -NON-REDUCING Sugars are Complicated, but Sucrose is a Perfect Example [Note if your Test for Reducing Sugars went Negative, there still might be Sugars in there, Non-Reducing Sugars.]
How is Starch Tested for?-Adding Iodine Solution to your Test Sample is Enough -Starch Present = Dark Blue Colour -No Starch Present = Brown/Orange Colur
How is Lipids Tested for?-Use Ethanol and Mix with the Test Sample also Included - until its Dissolved -Then pour into Water which can Result into 2 Results -Lipids Present = Milky Emulsion [Little Droplets] -No Lipids Present = Nothing.
How are Proteins Tested for? [Biuret Test]-Add Sodium Hydroxide to your Testing Solution making it Alkaline -Then, add Copper [II] Sulphate Solution which is Light Blue -If Protein Present = Solution will turn Purple -No Protein = Solution will Stay as Light Blue