STAGE 2 BIOLOGY ENZYMES TASK SHEET BASIC METHOD Materials: tofu paring knife chopping board ruler 50mL measuring cylinder 3x100mL glass beaker distilled water 5% pepsin solution 2M hydrochloric acid 2M sodium hydroxide solution ph test strips incubator electronic balance watch glass forceps sieve plastic teaspoon Method: 1. Cut 6 cubes of tofu with one centimetre dimensions. 2. Measure and record the mass of two tofu cubes. Calculate and record the average mass of the tofu cubes. 3. Measure 40mL of the pepsin solution and transfer it into one of the 100mL beakers. 4. Test the ph in the beaker by using the ph test strip. 5. Using the hydrochloric acid or sodium hydroxide adjust the ph of the solution to 3. 6. Carefully lower two cubes of tofu into the pepsin solution. 7. Repeat steps 2-5 for a pepsin solution with a ph of 6. 8. Incubate the beakers for 37 C overnight. 9. Re-weigh the remainder of the tofu cubes to obtain the final mass. 10. Calculate the percentage change in mass of the tofu.
DESIGN Introduction: Aim: Hypothesis: Remember: a hypothesis is a prediction of the results of the investigation. Independent variable: Dependent variable: Constant variables: Identify how you plan on keeping the variable constant e.g. identify volumes used if that is something that will be kept constant. Safety: Relevant MSDSs checked and important things noted: Hazards identified and minimised:
Abstract: Aim/Hypothesis: Method (a two sentence summary): Summary of results: An abstract is a brief summary of the whole practical report. The headings only show what things you need to include. DO NOT include these headings in the abstract. Conclusion: Results: Create a suitable table here that includes your independent and dependent variables.
DISCUSSION: (SPACE FOR NOTES) Data: What kind of association is demonstrated in the graph? OR If there wasn t enough data for a trend, why not? Only use the Discussion heading. The other subheadings here are only a guide to assist you in writing your discussion. How does this relate to the hypothesis/aim? Are there any outliers? Why might they have occurred? (Ignore if there were none) General improvements: What could be improved about the method? There might be some general improvements that are not linked in with errors. You can include them. How did it affect the results/efficiency/safety/etc? How could it be improved?
Random Errors: What was the random error? How did it affect the results both generally and specifically? Explain things concisely. Don t use fancy words when simple words suffice. Remember: random error affects precision. How could you change the method to reduce the effect of this error, and hence improve the investigations? (You can suggest more than one thing) What was the random error? How did it affect the results both generally and specifically? How could you change the method to reduce the effect of this error, and hence improve the investigations? (You can suggest more than one thing)
What was the random error? How did it affect the results both generally and specifically? How could you change the method to reduce the effect of this error, and hence improve the investigations? (You can suggest more than one thing)
Systematic Errors: What was the systematic error? Remember: systematic error affects accuracy. How did it affect the results both generally and specifically? Explain how redoing the experiment with different equipment would help to identify a systematic error. Conclusion: Answers the aim/hypothesis.
SA:V RATIO - Practical Assessment Student s initials: Category Skills Checklist Comments Set up of work area Has all apparatus required Apparatus logically set out at work area No unnecessary hazards present Uses work area methodically Measurement of volumes Uses appropriate measuring apparatus Carefully measures volumes Meniscus touches graduation line for required volumes Uses the correct volumes as per the method Other Precise ph or temperature obtained Tofu cubes cut precisely Masses recorded precisely Beakers labelled appropriately Area cleanliness Keeps work area logically set out for the entire investigation Does not put wet implements on bench space Careful when navigating around the work area Cleans up any spillages or breakages(as necessary) N/A Clean up Disposes of solutions appropriately Tofu disposed of appropriately Puts all used apparatus in the appropriate containers Is aware of hazards during cleanup