STAGE 2 AGRICULTURAL AND HORTICULTURAL SCIENCE
ASSESSMENT TYPE 2: Skills and Applications Tasks
RATE OF FERMENTATION
The aim of this experiment was to investigate the effect of yeast concentration on rate of fermentation. This was done by adding different level of yeast in suspensions into 20mL of glucose solution that was in a test tube sitting in warm water. The CO? would be collected in the test tube and therefore measure the rate of fermentation. The results supported the hypothesis that showed that the more yeast that was in the suspension the faster the rate of fermentation that was occurring.
All cells need to obtain energy through the breakdown of organic rich molecules (usually glucose). This process is known as respiration. If cells are unable to obtain oxygen that they need for the aerobic respiration, they start fermentation. Many plants and micro-organisms, such as yeast (fungi), carry out fermentation which is anaerobic respiration of glucose forming ethanol (Alcohol) and Carbon dioxide (refer to equation below).
Alcohol + Carbon dioxide
2C?H?OH + 2CO?
It is possible to measure the rate of fermentation by either measuring the production of heat, carbon dioxide or alcohol. This reaction is catalysed by enzymes such as those found in yeast and therefore it can be affected by a number of factors. If enzymes do not have their optimal temperature and pH they will not function at their optimal and this will therefore change the rate of fermentation. Other things that would effect this reaction are the yeast cells, because the enzymes in the yeast cells should influence the rate of fermentation.
To investigate the effect of yeast concentration (g/L) on the rate of fermentation, measured by the amount of carbon dioxide production.
?If the yeast concentration (g/L) increases then the rate of fermentation will increase till an optimum is reached?.
? Concentration of Yeast (10g/L, 20g/L, 30g/L, 40g/L, 50g/L)
? The rate of fermentation shown by Carbon dioxide production (mL)
? Amount of glucose
? Water Temperature (37?C)
? Volume of water in the yeast suspension
? Time of experiment
? Size of beakers
? Type of yeast
? Volume of water in the water bath
- 6 x Retort stand with clamp
? 6% Glucose solution
- 6 x Test tube with stopper
? 6 x 200mL Beakers
- Measuring Scales
? 6 x 50mL measuring cylinders
- Ceramic bowl
- 6x 10mL measuring cylinders
This fermentation practical consisted of 5 treatments of yeast solution with identical apparatus. Refer to the diagram below for the setup with labelled apparatus.
Figure 1 ? The setup of the experiment with labelled equipment and apparatus
1. Measure out 2,4,6,8 and 10 grams...