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Growing Microorganisms Introduction/ Aim: Yeast are a tiny form of fungi or plant-like microorganism (visible only under a microscope) that exist in or on all living matter i.e. water, soil, plants, air, etc. The yeast life cycle, like that of all higher organisms, includes a step known as meiosis, where pairs of chromosomes separate to give new combinations of genetic traits. People in today's society use yeast for controlled fermentation of food and drink; it is also used for baking. In this experiment I will be attempting to measure the growth of a yeast population and in doing this I will have to carry out certain methods to succeed. Below is a diagram on a yeast cells with arrows showing the parts of the yeast cell: Equipment/ Apparatus: * 250cm³ Beaker * Measuring cylinder to measure 50cm³ * A Cuvette * A Colorimeter * Sticky Labels * A Suspension of Yeast * Glucose Solution * Pipette Risk Assessment: This experiment is not that much dangerous so not much precaution is really needed, there are not dangerous chemicals, no hazardous gases etc. Below I have written the things you must look out for when carrying out this experiment. * You will be handling many glass equipment when doing this experiment such as beakers and measuring cylinders, you must be extremely careful
In humans toxic waste is excreted by the kidneys (Urea) however waste products from microbes build up in the environment and can kill them e.g. more than 15% alcohol is capable of killing the yeast cells making the alcohol. Procedure/ Method: 1. To begin the experiment you must firstly collect a 250cm³ beaker and place it down where you are going to do your experiment, you must then start off by using a measuring cylinder and measure out exactly 10cm³ of yeast suspension, make sure you don't spill any yeast because yeast has a bad smell. 2. You must then pour the yeast from the measuring cylinder into the beaker and then rinse out the measuring cylinder and then measure out 200cm³ of glucose solution and then pour it into a clean unused beaker; you must then stir very very gently. 3. Now you must rinse out the measuring cylinder and all the other equipment that have already been used and then place them onto the trolley. 4. At this point of the experiment the beaker must have a very small population of yeast cells which will grow within a few days times. You must now take a clean cuvette and fill it with a sample of your yeast population using a pipette, after that you must then collect your colorimeter and put it on, at this period of time it will begin to warm up.
Another improvement we could have if we was to use additional equipments in our experiment such as a Ph sensor, temperature control, exit gas and exit liquid flow, antifoam and so on. The Ph sensor would be helpful because we will be able to identify the Ph level and we could be able to adjust it using certain methods, the temperature control could be helpful because we wouldn't want to kill the yeast population so therefore having control over the temperature would be helpful, the exit gas and exit liquid flow would be helpful in the experiment because we will then be able to remove the waste products. Final Conclusion: Overall, from doing this experiment I think that it was successful and I came out with the results that I was expecting at the beginning of the experiment, improvements can be made to the experiment such as changing the method of the experiment and this may result in having more accurate results. From doing the experiment and this coursework I managed to prove that as the yeast population increases it will become more difficult for the light rays to pass through the yeast population filled cuvette and this will decrease the transmission percentage.
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