AQA A Level Biology Paper 1 100% CORRECT ANSWERS

Water removed from the reactants Condensation The addition of water to the reactants Hydrolysis Add 2cm³ of food sample (in solution). Add 2cm³ of benedict's Reagent. Heat the solution in a water bath for 3 minutes. Change from blue to brick red. CuO formed Test for Reducing Sugars Add 2cm³ of food sample.Add 2cm³ of dilute HCL then heat.Add 2cm³ of NaHCO3.Then do test for reducing sugars. Non-Reducing Sugars Add drops of iodine to starch solution. Colour change to blue-black Test for Starch Mix Test solution with ethanol. Shake for 1 minute. Add water. Cloudy white emulsion Test for Lipids Equal volumes of Test solution and NaOH. Add a few drops of biuret solution (dilute copper (II) sulphate solution). Colour change to mauve/purple Test for Proteins 1. Inhibitor is similar in shape to substrate so it impermanently binds to the active site. 2. Prevents ESC from forming, slowing rate Competitive inhibition (2) 1. Molecule will bind to allosteric site. 2. Binding causes a change in active site. 3. Permanently preventing further ESC. Non-competitive inhibition (3) 1. DNA helicase breaks the hydrogen bonds between the base pairs 2. 2 single strands formed as the double helix "unzips". 3. Free nucleotides in the nucleoplasm bond to the complementary bases on the strand. 4. DNA polymerase joins the new strands together by creating phosphodiester bonds. DNA Replication: Semiconservative (4)