Planning investigations - PAG 12
Hypothesis
Independent variable
Range and intervals of independent variable
Dependent variable and how it will be measured
Background information - needs to be relevant to the experiment (references)
Enzymes/stages in respiration
Enzymes and temp/kinetics
Q10
Optimum temperature for yeast - prior research
Need an online and an offline source (can use textbook)
Variables to control
Variable | Why controlled? | How? |
Volume of yeast | More respiration for a larger volume? | Use a set volume of 10cm3 which is the same for every condition |
Concentration of yeast | More concentrated - higher rate of respiration? | Use the same concentration for every condition - could use from the same sample |
Respiratory substrate | Some substrates are respired more efficiently/some can’t be respired by yeast at all | Use glucose for each temperature |
Volume of respiratory substrate | More respiration for a larger volume? | Use 10cm3 of respiratory substrate for every condition |
Measuring apparatus | Degree of uncertainty should remain the same | Use the same measuring apparatus |
pH | There’s an optimum pH for respiration so different pHs can offer the rate of respiration | Use a pH buffer |
Species of yeast | May have different respiration efficiency | Use the same species fro each condition |
Method
5 repeats, 5 temperatures - 25 pieces of data
Risk assessment ethics and environment
Glassware
Hot water
Electricity
Bacteria mixed in with yeast
Hazard | Risk | Control | Emergency procedure |
Glassware | Broken glass- being cut | ||
Hot water | Burning | ||
Thermostatically heated water bath | Electrocution | ||
Living microorganism | Possibility of pathogens mixed in with the yeast |
Equipment required