Catalase and Enzymes Investigation

Preliminary Test:

(Trial run)

The test will be about the amount of oxygen produced (in ml/cm³) from the chemical, hydrogen peroxide reacting with the enzyme, catalase. There is catalase in potatoes so I will be testing the chemical with this.

My method:

1. Collect all the equipment needed.
2. Wear goggles and gloves.
3. Attach the gas syringe on the clamp stand. The gas syringe is the most accurate way to measure the oxygen collected.
4. Cut out 2 pieces from the potato by using a borer so all the pieces will have the same diameter.
5. Use the filter paper to dry the potato pieces as they are quite moist.
6. Use a ruler to get accurate measurements.
7. On a tile, cut the potato pieces using a knife with a length of 4cm. Use a ruler to get accurate measurements.
8. Cut one of the pieces in half so the lengths of the potato are 2cm each.
9. Put the potato pieces in separate conical flasks.
10. Pour 30ml of hydrogen peroxide in a measuring cylinder.
11. Pour the chemical into a conical flask where the potato piece is.
12. Quickly attach the conical flask to the tube of the gas syringe and start timing.
13. Record the amount of oxygen produced after 40 seconds.
14. Repeat steps 10-13 for the other potato piece (whole).

Here are my results recorded in a table.

Amount of Hydrogen peroxide: 30ml

Time taken: 40 seconds

Unit: ml or cm³

The table shows the number of oxygen produced (in ml or cm³). It shows that more oxygen is produced when the concentration is high. For my actual test, I will change the amount of hydrogen peroxide to 20ml/cm³ because I used too much in the preliminary test. I will change the time to 90 seconds because 40 seconds is too short and this makes the results unreliable. Also, I will experiment on more potatoes with different surface areas and I will repeat the test 2 times for each in order to get accurate and reliable results. Any anomalous results also known as the outlier will be repeated.

Safety Points:

(Things to do to avoid danger)

• Wear goggles to protect your eyes from the hydrogen peroxide
• Tie hair back if needed to
• Wear gloves to protect your hands from the hydrogen peroxide
• Do not wear any jewellery

Surface Areas:

I will be testing 5 potato pieces and each has different surface areas.

• Surface area 1/Potato 1 – 4cm long (whole)
• Surface area 2/ Potato 2 – 2cm long x 2 (cut in half)
• Surface area 3/ Potato 3 – 1/3 long (cut in thirds)

• Surface area 4/ Potato 4 – 1cm long x 4 (cut in quarters)
• Surface area 5/Potato 5 – Mashed up

Fair Test:

To make my investigation a fair test I will:

• Make sure the weight or mass of the potato pieces are the same
• Make sure that there is the same amount of hydrogen peroxide in each flask
• Use a ruler to measure the size of the potato accurately
• Start the clock at the precise time of the reaction taking place and stop at the right time

Controlled Factors:

(Things affecting the experiment)

Independent Variable –

1. The size of the potato

• The potato pieces will have different surface areas to find out which one will react more with the hydrogen peroxide

Dependant Variables –

2. The amount of hydrogen peroxide

• The same amount of hydrogen peroxide will be used to be tested for each potato piece to make it a fair and reliable test

3. The time taken

• I will record the oxygen produced after the same amount of time for each potato piece being tested

Actual Test:

(The real experiment)

I have used my preliminary results to decide what range to investigate. I will use more ranges in surface areas.

My Method:

1. Collect all the equipment needed.
2. Wear goggles and gloves.
3. Attach the gas syringe on the clamp stand. The gas syringe is the most accurate way to measure the oxygen collected.
4. Cut out 5 pieces from the potato by using a borer so all the pieces will have the same diameter.
5. Use the filter paper to dry the potato pieces as they are quite moist.
6. Use a ruler to get accurate measurements.
7. On a tile, cut the potato pieces using a knife to the lengths of the 5 different surface areas listed previously.
8. Put the potato pieces in separate conical flasks.
9. Pour 20ml of hydrogen peroxide in a measuring cylinder.
10. Pour into the conical flask where the potato piece is.
11. Quickly attach the conical flask to the tube of the gas syringe and start timing.
12. Record the amount of oxygen produced after 90 seconds.
13. Repeat the test for this potato 2 more times.
14. Repeat this for the other potato pieces (Steps 9-13).

Table Results:

(Table form)

Amount of Hydrogen peroxide: 20ml

Time taken: 90 seconds

Unit: ml or cm³

I collected the data of the amount of oxygen produced (in ml or cm³) after 90 seconds.

I tested each potato with different surface areas 3 times. Then, I worked out the average to use for my graphs. The averages have been rounded up to the nearest whole number.

Graph Results:

(Graph form)

Line of best fit =

I used the results from my table to create a graph which shows the oxygen produced from each potato type which has different surface areas. I drew a line of best fit and this shows if there is any correlation.  

Conclusion:

My results in table and graph form shows that when there is high concentration, more volume of oxygen is produced. It shows that each potato type produces different amounts of oxygen so I have discovered that the surface areas of the potatoes affect the reaction rate. The rate of reaction varies in all the potato types because of the surface areas of the potato. I labelled the scattered diagram with the line of best fit to see what type of correlation it has. My scattered diagram for oxygen produced (y) against potato type (x) shows positive correlation but not as strong. All the points are close to the trend line. It shows positive correlation because the oxygen produced increases in all the potato types.

Finding out the average by working out the mean (mathematical term) shows the overall result for each potato type. Potato 5 (mashed up) shows the most oxygen produced with a figure of 21ml/cm³. Potato 2 (cut in half) shows the least oxygen produced with a figure of 12ml/cm³.This tells me that the amount of oxygen produced depends on the surface area of the potato and the concentration of catalase.

So my hypothesis was correct because I predicted that the greater the concentration of hydrogen peroxide, the higher the volume of oxygen produced. This happens because potatoes and livers contain the enzyme, catalase that catalyzes the breakdown of hydrogen peroxide to water and oxygen. This means that the stronger the concentration, the faster the breakdown is of hydrogen peroxide. Therefore, more oxygen is produced. Consequently, this explains how the lock and key works in the diagram below.

Evaluation:

1. I have evaluated the data I collected

I collected a good amount of results in order to draw a conclusion. I repeated the test a few times which helped me get reliable readings. My results were fairly accurate because I followed the procedure carefully. Also, the line of best fit in my graph of results showed a pattern with positive correlation. The points were close to the trend line. No anomalous results occurred so my results did not need to be repeated again. Since all the points are close to the trend line or the line of best fit on the scatter diagram, I would say the results are reliable enough as a suitable amount of repeats were done to make the test accurate. On the whole, there was enough data in order to achieve reliable outcomes. The graph showed positive correlation but it was not as strong because all the potato types had their own surface area and as oxygen produced, the concentration of catalase got higher. The surface areas of each potato affected the amount of oxygen produced so the readings for each potato type are different. In my conclusion, I fully explained the results by using the data I collected in a table, a graph and my knowledge on the lock and key. When doing the experiment, I carefully carried out the procedure to aim for reliable results. My results covered a big enough range to support a firm conclusion because doing the test 3 times and also working out the average for each potato type (different surface areas) helped me draw to a reliable conclusion. Overall, I have collected a sufficient amount of accurate and reliable data in order to get reliable results for me to make a firm conclusion.

2. I have evaluated my method

In my method, I encountered a few problems. The gas syringe would fail to work properly a few times because the tube wasn’t attached to the conical flask properly and when the tube was not held up in level with the flask, it affected the readings of the oxygen produced on the gas syringe. However, all the equipment used was suitable for this investigation. The other factors that needed to be controlled were done successfully because I made sure the potatoes were all timed for 90 seconds and also the amount of hydrogen peroxide (20ml) was the same in each conical flask. I used a measuring cylinder to make sure the right amount was used. Although my procedure was not done the best it could have been done, my results were fairly precise because I carefully followed my procedure which involved the use of reliable equipment such as a measuring cylinder, stop clock, gas syringe and a ruler. These things helped me make the results accurate. There was not enough equipment which was needed to collect data. For instance, I needed more conical flasks in order for me to test all the potatoes. I managed to collect all the data needed but it took a while for the experiment to be completed because I had to wash out the conical flasks to be used for other potatoes and for repeats. The results are still accurate enough so the equipment I used did not have a big affect on my results.

Here are some improvements I can make in order to make my results more accurate and reliable:

• The same type or kind of potato should be used in the investigation so it contains the same quantity of catalase enzyme in order to have a fair test and accurate results

• After the potato pieces have been cut by a borer, cut by a knife when measured by a ruler (to get the right surface area) weigh the potato pieces to find out the mass as all the pieces should still weigh the same for the investigation to be accurate  

• During the experiment, shake the conical flask the same amount of times for each different surface area of the potatoes being tested as this will speed up the reaction and this will give another set of reliable results

3. I have evaluated my conclusion

In my conclusion, I have fully explained the results by using the data I collected in a table, a graph and my knowledge on the lock and key. When doing the experiment, I carefully carried out the procedure to aim for reliable results. Also, the line of best fit or the trend line showed positive correlation but wasn’t as strong which means the data collected was not accurate as possible. So in future, I will record the masses of the potato pieces and make sure they all weigh the same even though they all have different surface areas. Plus, the experiment will be repeated several more times. This will give a better outcome of the data collected which makes the conclusion have an enhanced description or explanation. Therefore, the whole investigation and its aim will be performed successfully.