Sicheng's+BIojournal

__6April10:__ __**Bio Report #4**__

Investigating the Effect of Temperature and pH on Enzyme Action

Apparatus and materials: Bunsen burner, tripod stand and gauze, 3 water baths, thermometer, 12 test tubes, measuring cylinder, 4 250ml beakers, 2 white tiles, 2 droppers, ice cubes, distilled water, test tube holder, stop watch, goggles, 2% starch solution, 1% amylase solution, 1M Hydrochloric acid solution, 1 M Ammonium Hydroxide solution, iodine solution.

Methodology:

1. Label 8 test tubes A1, A2, B1, B2, C1, C2, D1 and D2. 2. Add 5cm³ of starch solution to tubes A1, B1, C1 and D1. Add 3cm³ distilled water to D2, and then 3cm³ of amylase solution into tubes A2, B2 and C2. 3. Place

Results:
 * Test tube ||  Contents  ||  Temperature/degree Celcius  ||  Iodine Test  ||  Conclusion  ||
 * A1 || Starch solution || 0 || Dark blue || There are no enzyme activity at 0 degree Celcius. ||
 * A2 || Amylase solution || 0 ||^  ||   ||
 * B1 || Starch Solution || 37 || Brown || There is enzyme activity at body temperature. ||
 * B2 || Amylase Solution || 37 ||^  ||   ||
 * C1 || Starch solution || 100 || Dark blue || There is no enzyme activity at 100 degree Celcius. ||
 * C2 || Amylase Solution || 100 ||^  ||   ||
 * D1 || Starch Solution || 37 || Dark blue || Control; starch solution will not be digested in water/without enzyme activity. ||
 * D2 || Distilled water || 37 ||^  ||   ||


 * Test tube ||  Contents  ||||  Iodine Test  ||  Conclusion  ||
 * ||  || Before || After ||   ||
 * W || 2cm³ starch solution + 2cm³HCL + 2cm³ amylase || Dark blue || Yellow || Acidity/low pH affects the enzyme activity. ||
 * X || 2cm³ starch solution + 2cm³ distilled water + 2cm³ amylase || Dark blue || Dark blue || Water does not affect enzyme activity. ||
 * Y || 2cm³ starch solution + 2cm³ NH^4 + 2cm³ amylase || Dark blue || Dark blue || Alkalinity/high pH does not affect enzyme activity. ||
 * Z || 2cm³ starch solution + 4cm³ distilled water || Dark blue || Dark blue || Control; starch solution will not be digested in water/without enzyme activity. ||

Tube B shows that starch digestion has occured. The iodine test was negative indicating that there was no starch present, so starch digestion must have occured. In tubes A, C and D, the mixtures gave a blue black colour showing that starch digestion did not take place. Starch digestion takes place due to enzymatic activity, which is affected by the temperature. Therefore, enzymatic activity can take place in B because the temperature is that of body temperature, but cannot take place at temperatures of 0 and 100. Tube D acts as a control indicating that enzymatic activity is the cause of starch digestion since starch digestion is unable to take place in distilled water.
 * Part A**

Conclusions: Enzymatic activity is affected by the temperature by allowing or disallowing it to take place. There is no enzymatic activity in low temperatures such as 0 degree Celcius nor high temperatures such as 100 degree Celcius. Enzymatic activity takes place at body temperatures around 37 degree Celcius.

Tube W shows that starch digestion has occured. Before, the iodine test was positive and after, the iodine test was negative, showing that the original starch that was present had been digested. In tubes X, Y and Z, the mixtures gave a blue black colour showing that starch digestion did not take place. It takes place due to enzymatic activity, which is affected by the pH. Therefore, enzymic activity cannot take place in tube X which contains dissolved water with the pH of 7, and in tube Y with the pH of higher than 7 which shows that higher pHs affect enzymatic activity. Tube Z acts as a control indicating that enzymatic activity is the cause of starch digestion since starch digestion is unable to take place in distilled water.
 * Part B**

Conclusions: Enzymatic activity is affected by the pH level by allowing or disallowing it to take place. There is no enzymatic activity in solutions with pH levels of 7 or more. Enzymatic activity can take place in solutions with pH levels lower than 7(acidic).

Overall, temperature and pH levels affect the enzymatic reaction by altering the speed of enzymatic reaction.




 * __Bio Report #3__**

__Agar Experiment__ Hypothesis: When the surface area is larger, diffusion can take place faster. Therefore, when the pieces of solid agar are smaller, the surface area is larger and the conductivity will then be higher.

Apparatus: Razor blade, white tile, ruler, glass rod, 3 beakers, solid agar, data logger(with conductivity probe) Constant Variables: The amount of water in the beaker, the volume of agar

Methodology: 1. Cut 1 piece of agar into 8 cubes of 1cmx1cm1cm and another into 54 cubes of 0.5cmx0.5cmx0.5cm. The last piece is kept intact. 2. Fill a beaker with 200ml of water and place the conductivity probe in it 3. Put the agar block in and stir the water with the glass rod while holding the probe still 4. Repeat steps 2-3 with the 1cmx1cmx1cm cubes and 0.5cmx0.5cmx0.5cm cubes 5. Record down results and draw trends Results:


 * ** Type of algae block ** |||| ** Conductivity ** ||
 * || Before || After ||
 * **2cmx2cmx2cm (x1)** |||| 0.2 0.9 ||
 * **1cmx1cmx1cm (x18)** |||| 0.6 1.2 ||
 * **0.5cmx0.5cmx0.5cm (x64)** |||| 0.3 2.1 ||


 * **Type of algae block** || **Surface area: volume** ||
 * **2cm x 2cm x 2cm** || 3:1 ||
 * **1cm x 1cm x 1cm** || 6:1 ||
 * **0.5cm x 0.5cm x 0.5cm** || 12:1 ||

Didn’t hold the probe still when stirring
 * Errors: Did not use forcepts because we couldn’t find it in the tray

Discussion: The trend shown is that the larger the surface area, the higher the conductivity. This is because there is less surface area for particles to diffuse in or out of the agar and therefore, the rate of diffusion is affected. When the surface area decreases, diffusion is slower. Similarly, when the surface area increases, diffusion speeds up. Another trend shown is that the smaller pieces the agar is cut into, the bigger the surface area is compared to the volume. When the surface area increases, the conductivity increases which shows that the volume of the agar does not determine the rate of diffusion. Rather, the surface area does.

__Beetroot Experiment__ Hypothesis: Two factors that affect the rate of diffusion are the surface area and the change in external environment—where the liquid the beetroots are placed in vary. When placed in hot water, diffusion would speed up. Since alcohol evaporates faster, I believe its molecules move faster than water molecules and therefore diffusion takes place faster. Therefore, the beetroot in E, which has the largest surface area, would turn the reddest, followed by beetroot in D, then C, B and lastly A. Methodology: 1. Use a ruler and scapel to cut the beetroot into 15 discs of 2mm each. 2. Cut 3 discs of beetroot into smaller pieces. 3. Rinse the beetroot discs till they are colourless. 4. Prepare 5 test tubes:

5. Place 3 discs of beetroot in tube A-D each and all the chopped beetroot into tube E. 6. Leave the tubes for 15 minutes. 7. Shake tubes gently and hold it against white tile to note colour. 8. Test the colour of the liquid in the test tubes using a colorimeter.
 * Tube || Content ||
 * A || 4ml of water ||
 * B || 4ml of 25% alcohol ||
 * C || 4ml of 50% alcohol ||
 * D || 4ml of hot water ||
 * E || 4ml of water ||

Observations: A: Barely red, could only see when compared against white tile B: Around the same colour as C (reddest compared to the rest except C) C: Around the same colour as B (reddest compared to the rest except B) D: Slightly less red than B and C E: Around the same as D; darker than A

Results:
 * ** Tube ** || ** Results(compared to 100% ) ** ||
 * **A** || 103.1 ||
 * **B** || 71.0 ||
 * **C** || 33.2 ||
 * **D** || 85.2 ||
 * **E** || 85.5 ||

Errors: Keep accidentally touching the knob—results may therefore not be accurate

Discussion: Both test tubes A and E are filled with 4ml of water yet the rate of diffusion of the red pigment from the cell to its surrounding is faster in test tube E. This is because in E, beet root are chopped into smaller pieces, like the agar pieces and therefore there is larger surface area. When the surface area is larger, there is more room for the molecules to move in and out of the cell. Therefore, more red pigment from the beetroot in E diffused into its surroundings than in A. In C, the rate of diffusion of the beet root cells is the fastest. This is because cell membranes come in contact with alcohol, the lipid molecules move more freely and molecules can move in and out more easily. Therefore, alcohol increases the rate of diffusion. However, there might be a mistake in either B or C because there might not be such a big difference between beetroot in 25% alcohol and 50% alcohol. Beetroot cells in D have around the same rate of diffusion as the beetroot cells in E. This shows that both surface area and temperature increase the rate of diffusion by similar amounts. The trend is that the rate of diffusion is affected most by alcohol followed by the surface area and temperature. The limitations are that the results might not be fairly accurate because the knob might be unconsciously touched and therefore the 100% mark might be moved either slightly higher or lower.

Conclusions(from both experiments): The rate of diffusion is affected greatly by the external environment of the cell. The increase of surface area, temperature, and concentration of alcohol all increase the rate of diffusion.