Anaerobic respiration is the process of releasing energy from the breakdown of glucose in the absence of oxygen. Yeast can carry out anaerobic respiration in a glucose solution.
Glucose ---> Ethanol + Carbon dioxide + Energy
The rate of anaerobic respiration is affected by several factors such as temperature, pH values and nutrients.
Based on the above information and equation, design a laboratory experiment to investigate the effect of temperature on the rate of anaerobic respiration in yeast.
The planning of your experiment must include the following aspects:
§ Problem statement
§ Aim of investigation
§ Hypothesis
§ Variables
§ List of apparatus and materials
§ Technique used
§ Experimental procedure or method
§ Presentation of data
§ Conclusion
ANSWER
:1. Aim of investigation
To investigate the effect of temperature on the rate of anaerobic respiration in yeast.
2. Problem statement
What is the effect of temperature on the rate of anaerobic respiration (in yeast)?
3. Hypothesis
The higher the temperature, the higher the rate of anaerobic respiration (in yeast).
4. Variables
Manipulated variable: Temperature
Responding variable: Rate of anaerobic respiration//No of bubbles released//Time taken for lime water to turn chalky
Fixed variable: Volume/conc. of yeast suspension/glucose/pH/Time taken
5. Apparatus:
Boiling tube, Manometer/Capillary tube, Water bath//Beaker + thermometer,
Stopwatch, Marker/thread, Rubber stopper, Ruler, Rubber tubing, Retort stand, measuring cylinder
Material :
Yeast suspension / Yeast, Glucose solution, Paraffin oil (Yeast & Glucose – must have)
6. Technique
Using a ruler to record the change in height of the colored liquid/Record the number of bubbles released (after 10 minutes) using a stopwatch
//Calculating the rate of anaerobic respiration (in yeast) by using the formula :
Number of bubbles / Change in height
Time taken
//Take and record the time taken for the lime water to turn chalky using a stopwatch.
7. Procedure :
1. Set up the apparatus as shown in diagram.
2. Place the boiling tube with 15 cm3 of glucose solution in a beaker at 20oC for 5 minutes.
3. Add 15 cm3 of yeast suspension into the boiling tube.
4. Mark the initial height of coloured liquid in manometer.
5. Start the stopwatch and mark the level of coloured liquid in the manometer after 10 minutes.
6. Record all data in a table.
7. Repeat step l, 3, 4, 5 and 6 by placing the boiling tubes in a water bath at temperatures of 30oC, 40oC and 50oC.
8. Make sure all the joints of the apparatus are air tight //Repeat the experiment for each temperature to get average readings.
9. Plot a graph of rate of anaerobic respiration in yeast against temperature.
Precaution :
1. Ensure the temperature is stablised at the fixed temperature before taking the reading if the height of the coloured liquid//counting the number of bubbles released.
2. Make sure all the joints of the apparatus are air tight //Repeat the experiment for each temperature to get average readings.
8. Result: Draw a table
9. Conclusion:
Hypothesis is accepted. The higher the temperature, the higher the rate of anaerobic respiration in yeast.
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