Biology Alternative To Pratical Guide IGCSE CIE BIOLOGY

• what equipment do you need?

  2 sharp pencils

  soft rubber

  blue/black pen

  sharpener

  ruler

  caculator
• forceps

  
• mounted needle

  
• scissors

  
• scalpels

  
• beakers

  
• test tube and test tube racks

  
• syringe

  
• measuring cylinder

  
• spotting tile

  
• dropping pipette

  
• hand lens

  
• thermometer

  
• funnel

  
• glass rods

  
• petri dishes

  
• inoculating loop

  
• litmus paper

  
• universal indicator paper

  
• substance being tested for: starch

  chemical: iodine

  positive result: changes from yellow-brown to blue-black
• substance being tested for: reducing sugar

  chemical: benedict's solution

  positive result: changes from blue to green (small amount) , yellow/orange ( moderate amount of sugar) or red (lots of sugar)
• substance being tested for: protein

  chemical: biuret's solution

  positive results: blue to purple
• the substance being tested for: fats

  chemical: ethanol emulsion test- substance dissolved in ethanol. the solution is then dissolved in water

  positive result: if lipids are present in the mixture it forms emulsion
• the substance being tested for vitamin c

  chemical: DCPIP

  positive result: blue to colouress
• hydrogen carbonate indicator changes colour depending on how much carbon dixode is present.
• hydrogen carbonate indicator is used to show carbon dioxide concentration in solution.
• test for carbon dioxide: limewater test, turns cloudy/milky
• hydrogen carbonate table

  
• state the name of an indicator that could be used to show that the gas produced by the yeast is carbon dioxide and give the result of a positive result 


  indicator: limewater or hydrocarbon

  positive test result: milky/cloudy or yellow
• state the solution that would be used to test for the presence of starch and give the result of a positive result


  solution: iodine solution

  positive test result: blue-black
• the independent variable is the thing you change in an investigation
• the dependent variable is what you measure in an investigation
• the control variable is what you keep the same during an investigation
• method: a step-by-step set of instructions on how to carry out the investigation
• risk assessment: a risk assessment explains how to reduce the chance of damage to equipment or injury to people
• 2/3 repeats of an experiment for a more reliable result not accurate.
• plan an investigation to determine the effect of temperature on the breakdown of starch by enzymes


  Use Benedict's reagent to measure reducing sugar produced at set times/ use a hot water bath and a thermometer to measure the temperature level

  independent variable: using at least two different temperatures

  variable kept constant :

  the same type of enzyme

  same pH

  dependant variable: concentration of reducing sugar produced

  repeat investigation at least 2 times to find an average for a more reliable result

  safety precaution: wear safety goggles etc..
• planning questions


  full plan: 6 marks

  method: 3 marks

  identify variables: 2 marks

  safety: 1 mark
• always show calculation question answers to 2 or 3 significant figures
• nanometer = 1

  micrometer = 0.0001

  millimeter = 0.000001