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Ib Biology Catalase Coursework

 

Internal AssessmentHelp Notes for the TeacherDesign

For this type of practical it is best to give the students an open-ended question,without providing them with instructions for methods or materials. The studentsshould be supplied with the materials they ask for. If these are not available, thestudent would do some alteration in the plan in order to carry out the experimentwithin the available resources.

Aim

: the student must enlarge on the given question to make it more specific for theinvestigation planned. For example if the question is testing the factors affectingenzyme activity, the aim can be: effect of temperature on the rate of breakdown of starch by amylase. Other students might come up with other types of enzymes, other factors and different plans for measurement and collection of data.

Hypothesis

is what the student expects will happen during the experiment. Thisshould be supported and explained scientifically from books and other resources. If ascientific explanation is not shown clearly and in sufficient detail, no marks aregained for this part of the criterion.

Variables: there are three types of variables

1.

Independent

variable:

this is the one changed during the experiment in order totest its effect. For example if temperature is changed to test its effect on enzymeactivity, then temperature is the independent variable. In a graph, the independentvariable is on the x-axis.2.

Dependent

variable:

this is the one affected by the independent. In the aboveexample, enzyme activity is the dependent variable, which can be measured in theform of time, volume, mass, length etc. The independent factor is plotted on the y-axis3.

Constant variables:

these are the factors which should be kept constant duringthe experiment. For example if we are changing the temperature to test its effecton enzyme activity, then concentration and pH should be kept constant.

Kevin Le IB Biology HL The Effects of Non-Competitive Inhibitors on Catalase Reaction Rate Introduction: A number of different factors affect an enzymes ability to catalyze reaction. Enzymes serve numerous purposes, but in general, enzymes will lower the activation energy of reaction, otherwise a catalyst for reactions. The testing of the factors that affect the efficiency of enzymes is called enzyme kinetics. Factors include temperature, pH, surface area, inhibitors, substrate concentration and enzyme concentration. Each factor will have an optimum, such as temperature where generally 30 o C is the optimum temperature or pH which varies amongst enzymes. The experiment will test the enzyme kinetics of catalase. Catalase is found in all living organisms and catalase the reaction of hydrogen peroxide, a poison to living tissue, into water and oxygen gas. The factor that will be tested is the effect of inhibitors on catalase. The two types of inhibitors are competitive inhibitors and non-competitive inhibitors. The difference between the two is that competitive inhibitors will slow the activity of an enzyme, however in the end; the reaction will have an equal product concentration in comparison to the reaction without an inhibitor. On the other hand, non-competitive inhibitors will not only slow the activity, but also decrease the amount of substrate concentration. This is because non-competitive inhibitors will attach to the enzyme and alter the active site of an enzyme, making the substrate unable to bind to the active site. The experiment will test the effect of the non-competitive inhibitor, copper (II) sulfate (CuSO 4 ), on catalase at various concentration. Research Question: How do different concentrations of the non-competitive inhibitor, copper (II) sulfate (CuSO 4 ) affect the rate of catalase activity? Hypothesis: If various concentrations of copper (II) sulfate, a non-competitive inhibitor, are added to catalase, then they will decrease the rate of catalase activity and higher concentrations of copper (II) sulfate, such as 2.00 or 1.00 mol concentration, will have a greater impact on slowing the rate of catalase activity. Variables: Independent: Concentration of non-competitive inhibitor copper (II) sulfate Dependent: Rate of catalase activity, measured by time it takes to reach a certain point then using the formula of rate = distance/time Control: Test tube with distilled water, i.e. 0.00 mol copper sulfate, thus no inhibitor will affect the rate on enzyme reaction

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