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Respiration of yeast

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14 JULY 2006 BIOLOGY COURSEWORK ~ RATE OF RESPIRATION OF YEAST INVESTIGATION INTO WHAT AFFECT DOES THE CONCENTRATION OF GLUCOSE HAVE ON THE RATE OF RESPIRATION OF YEAST Experiment Aim The aim of this investigation is to carry out a practical and observe how the concentration of glucose (sugar) affects the rate of respiration of yeast. I will write a report explaining how the intensity of the concentration of glucose affects how fast yeast respires. What Is Respiration? For a body to be fit, all the muscles and organs are required to be working correctly. For them to work perfectly, the cells that build up the tissue of that particular function need energy. That energy is provided by respiration. Respiration is needed in every single type of cell, including single celled micro-organisms. But there are two types of respiration: * Aerobic respiration * Anaerobic respiration Aerobic respiration~ Oxygen and glucose are transported into a cell. If it is respiration in a human cell, oxygen is inhaled, and glucose is taken from starch. If the conditions are appropriate, the enzymes around the cell speed up the process of the entrance of these two chemicals into the cell. When the oxygen and the glucose enter the cell, water and carbon dioxide (along with some energy) are released from the cell. The carbon dioxide and the water leave the cell. The chemical formula for this is: Glucose + Oxygen Carbon Dioxide + Water + Some C6H12O6 + 6O2 6CO2 + 6H2O Energy Glucose and oxygen are essentially needed for aerobic respiration. Anaerobic respiration~ In animals or humans, muscle cells use this type of respiration when a person does a burst activity (such as sprinting or lifting weight rapidly). In this case, the oxygen in the blood cannot reach the muscle to deliver oxygen quick enough to perform aerobic respiration. So the cell breaks only the glucose down and releases a substance called lactic acid. ...read more.


This is the main reason why we wear safety glasses. As we will be using apparatus which is made of glass, it will be dangerous for students to behave insensibly as the result could lead to a hospital visit. We should take extra precautions with the water heater and the hot water itself as students could be burned if the apparatus is handled inappropriately. In all cases, the same conclusion leads to the safety of the experiment: the students should carry out every action with caution and thoughtfulness. Fair Testing ~ As the class is investigating different concentrations of glucose in separate groups, regulations have to be kept for the conditions of the investigation to be the same for each and every practical. As we are observing reactions in different conical flasks, the amount of water essentially needs to be the same for the glucose to be dissolved into. Increasing the amount of water will decrease the concentration of glucose, and vice versa: the volume of water for every experiment is set at a fix amount of 100cm� (measured out with a measuring cylinder). As the chemical reaction inside the cell occurs best in 35�C-40�C environmental temperature, we need every single solution (in which the yeast will respire) to be at precisely this temperature. The water will be heated to the correct temperature in a water heater and left at that temperature for a specific amount of time. The time in which the glucose will be recorded vitally needs to be permanent for each group of investigators, for if one group let the yeast respire for longer than the rest, their outcomes might me abnormally dissimilar and against the expected pattern, forming a weak correlation on the graph. It is absolutely vital for the yeast in every solution to be equal, as a variation in the quantity could cause the experiment to go tremendously flawed. ...read more.


The temperature that we set the water bath to was not measured afterwards, but just assumed to be correct. So to make this matter improved, we could have fetched a reasonable thermometer to assure ourselves that the temperature of the solution was correctly between 35�C and 40�C (preferably at precisely 37�C). Below is an example of a thermometer. If more time was allowed, I would have assured my outcomes many times by repeating the investigations several times. As I only have two sets of outcomes, it is annoying to see that there is a margin gap between the two sets of results. As more sets of results would have been recorded, the average outcomes, for the graph, would have been more precise. The way we timed our experiment was by looking at the wall clock. But in actual fact, we were being really inaccurate. We might have gone up to a minute's difference. For the sake of the accuracy of the investigation, we should have set a stopwatch as soon as we had begun the investigation. Below is an example of a stopwatch. This is a precise stopwatch as it is a digital one instead of an analogue one with hands. Whatever the state of the equipment, the apparatus we used was the best we could use at our stage of educational experience. We cannot argue why we did not get more advanced equipment as the equipment we used was accurate, but imperfect. I can surely say that, for a satisfactory experiment, this investigation was a complete success. Additional Investigations Additionally, we could have taken the following investigation(s) into action: * An investigation into how the temperature affects the rate of respiration of yeast. * (Maybe) What affect salt and sugar (as a combination) have on the rate of respiration of yeast? Do they stabilise or do they have a different affect than what is expected? ?? ?? ?? ?? Syed Jafri ~ 11 East ~ Miss. Jordan ~ Page 1 of 11 ...read more.

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