unit 3 Flashcards
temperature on amylase + starch hypothesis
as temperature increases, the rate of reaction will increase until an optimum is reached, after the rate will decrease as the enzyme denatures.
temperature on amylase + starch equipment list
Amylase (1%), starch (1%), pH buffer (7), iodine, spotting tile, 5ml pipettes, test tubes and test tube rack, marker pen, thermometer, water bath
5ml pipettes to measure 5ml of each solution is accurate because equipment has low percentage error
pH buffer because pH affects rate of enzyme reactions (tertiary structure, H-bonds and ionic bonds)
Electronic water bath and thermometer because more accurate than Bunsen burner for maintaining and controlling temperature
effect of temperature on amylase + starch method
Independent variable - temperature, 20-60 ℃, go up in 10 ℃
Dependent variable - time taken (s) for orange iodine to stay orange, continuous data to be recorded in results table (you could sketch the results table…), using a stop watch which goes to 0.00 of a section so that time in seconds is precise and accurate to 0.005s
Amylase and pH buffer added and heated to desired temperature in one tube
Starch heated to a desired temperature in another separate tube
Ensure reaction mixtures are at desired temperature before mixing, because reaction will start as soon as starch is added and chemicals won’t be at temperature initially
Compare results to a negative control - well with just iodine, well with iodine and amylase only, well with iodine and pH buffer - to ensure that they don’t affect results and that only starch affects results
effect of temperature on amylase + starch data analysis
Time taken (s) will be collected at least 2-3 times and an average will be calculated after discounting anomalies to get a reliable average
Average time taken will be converted into rate of reaction
Looking for clear end point (iodine to stay orange) so rate = 1/time
Rate = s-1
Rate will be in decimals, so convert to standard form as X10negative-power
Line graph will be drawn showing rate (s-1in standard form) (on Y axis) against temperature (℃) (on X axis) (you could sketch the graph…)
effect of temperature on amylase + starch health and safety
Iodine - irritant - low risk - wear gloves
Glassware - sharp edges - low risk - clear away ASAP
Safety goggles
Lab coat and Disposable nylon gloves
effect of temperature on amylase + starch control variables
volume and concentration of amylase
volume and concentration of starch
pH
effect of increased substrate on enzyme controlled reaction hypothesis
As the concentration of HP increases, the rate of reaction catalysed by Catalase (volume of oxygen) will increase.
Because, there will be more collisions between HP and the Active sites of Catalase – so more ESCs.
effect of increased substrate on enzyme controlled reaction equipment list
Catalase from yeast – because its an easy and cheap source of liquid catalase.
Hydrogen peroxide (0%-10%, 2% intervals).
Gas syringe – to measure the volume of O2 gas released (cm3)
Stopwatch – to accurately measure time (seconds for precision).
Clamp and Boss stand – secure test/safe…
Thermometer and water bath to measure temperature (°C)
pH buffer (7)
10ml pipettes (with 1ml intervals) to accurately measure out volumes (0.5ml percentage error)
Equipment,
Techniques
Procedures
Justification – precision, accuracy, percentage error and potential error
effect of increased substrate on enzyme controlled reaction method
Independent V – Concentration of HP (range and intervals %)
Dependent V (raw) – Volume of O2 (cm3) collected over 10 second intervals for 4 minutes.
Dependent V (processed data) – rate of reaction (volume oxygen produced / 4 minutes) = cm3/min-1)
Draw the results table….
Independent variable – what range will be selected and what intervals will be used, is the data going to be continuous or discrete, what units will be used
Dependent variable – how it will be measured, what units will be used (precision and accuracy)
A numbered and logical step-by-step account of what will be done, how it will be done and why it will be done – linked to scientific reasoning.
effect of increased substrate on enzyme controlled reaction data analysis
Processed data – rate of reaction (volume oxygen produced / 4 minutes) = cm3/min-1)
Suggest / sketch graph = line graph
(X axis – HP concentration %)
(Y axis – Rate of Reaction cm3/min-1)
3 repeats for each HP concentration used – so that… reliable average and discard anomalous results
Spearman’s Rank Correlation coefficient analysis – statistical test to determine extent of correlation.
How the raw data can be processed to make it more comparable – i.e. percentages, ratios, fractions
How the raw/processed data can be summarised – i.e. averages
Identification of anomalous results
Statistical tests to use
Results table headings
Graph type to draw
effect of increased substrate on enzyme controlled reaction health and safety
Health and safety
Hydrogen peroxide – corrosive – low risk – precautions (PPE).
Glassware – could break – cuts – low risk – precautions (PPE)
Yeast – biological contamination – low risk – precautions – autoclave samples and wash hands at the end
Hazards for equipment
Risks for method steps
effect of increased substrate on enzyme controlled reaction control variables
Temperature – affects enzymes (kinetic energy / H-bonds and Ionic bonds) – control with water-bath and check with thermometer (°C)
pH – affects enzymes (H-bonds and ionic bonds) – control with pH buffer 7 (cells are 7.2) so is close to optimum for Catalase.
Concentration of catalase – affects collisions (use 5% throughout)
Volume of yeast and catalase (5ml each)
List of controls
Why it is important to control each variable listed (i.e. how would they affect the results otherwise)
displacement reactions of different metals releasing thermal energy hypothesis
if the metal reacts with the metal salt solution then thermal energy is released because a displacement reaction has occurred. This happens because the metal is higher up in the reactivity series than the metal salt solution.
displacement reactions of different metals releasing thermal energy equipment list
weighing scale
metal salt solution
4 polystyrene cups
stirring rod
stopwatch
displacement reactions of different metals releasing thermal energy method
IV-metal DV-temperature
1. The first step when carrying out this practical is to weigh out 10g of each of the metals magnesium, zinc, lead and copper using the same weighing scale. Do this four times
2. then measure out 50ml of the metal salt solutions, magnesium sulphate,
zinc sulphate, and lead nitrate. Make sure to use the same concentration 0.1 mol/dm^3 of each. do this four times.
3. pour the first metal salt solution into the polystyrene cup and using the thermometer take the initial temperature
4. add the first metal into the salt solution and start the timer for 5 minutes
5. stir the mixture using a stirring rod at regular intervals
6. stop the clock after 5 minutes and take the final temperature
7. repeat step 1-6 3 times
8. repeat step 1-7 for each metal
