Yeast Fermentation

Topics: Oxygen, Carbon dioxide, Gas Pages: 11 (3511 words) Published: January 19, 2011
Title :
Measuring the rate of oxygen uptake.

Objectives :
1. To demonstrate the uptake of oxygen in respiration.
2. To measure the rate at which an organism respires.
3. To learn how to set up the apparatus for respirometers.

Introduction :
A respirometer is a device that been used to measure the rate of respiration of a living organism. This can be measured by calculating the rate of exchange of oxygen and carbon dioxide. A simple respirometer designed to measure oxygen uptake or CO2 release consists of a sealed container with the living specimen together with a substance to absorb the carbon dioxide given off during respiration, such as soda lime pellets or cotton wads soaked with potassium hydroxide. The oxygen uptake is detected by displacement of coloured liquid in a thin glass U-tube connected to the container. When the organism takes in oxygen it gives off an equal volume of carbon dioxide. The soda lime or KOH will absorbed this carbon dioxide therefore air will be sucked in from the manometer to keep the pressure constant. The rate of changes gives a direct and reasonably accurate reading for the organism's rate of respiration.Whether measuring a whole organism or a sample, a respirometer needs to be sealed to collect valid information. The environment inside the respirometer is tightly controlled and monitored to collect data without causing injury to the organism being studied. These devices must be carefully monitored during use to avoid creating a dangerous situation inside the respirometer. If the space becomes filled with metabolic wastes, the organism may not be able to breathe, and conversely, if the organism uses up substances such as oxygen, it will be in danger. Tight controls of the environment ensure that the pressure in the manometer is under control.

The term respiration has two relatively distinct meanings in biology. First, respiration is the process by which an organism takes oxygen into its body and then releases carbon dioxide from its body. In this respect, respiration can be regarded as roughly equivalent to "breathing." In some cases, this meaning of the term is extended to mean the transfer of the oxygen from the lungs to the bloodstream and, eventually, into cells. On the other hand, it may refer to the release of carbon dioxide from cells into bloodstream and then to the lungs to be released out from body. Second, respiration also refers to the chemical reactions that take place within cells by which food is "burned" and converted into carbon dioxide and water. In this respect, respiration is the reverse of photosynthesis, the chemical change that takes place in plants by which carbon dioxide and water are converted into complex organic compounds. To distinguish from the first meaning of respiration, this burning of foods is also referred to as aerobic respiration. All animals have some mechanism for removing oxygen from the air and transmitting it into their bloodstreams. The same mechanism is used to expel carbon dioxide from the bloodstream into the surrounding environment. In many cases, a special organ is used, such as lungs, trachea, or gills. In the simplest of animals, oxygen and carbon dioxide are exchanged directly between the organism's bloodstream and the surrounding environment. All forms of respiration require some form of gaseous exchange. In aerobic respiration, oxygen must enter our blood and carbon dioxide must leave the blood through our lungs. Gaseous exchange is the exchange of Oxygen and carbon dioxide across a respiratory surface.. Animals which live on dry land use lungs. Our lungs have an enormous surface area so that Oxygen can get into the blood quickly enough and carbon dioxide can get out of our blood quickly enough. Our lungs contain billions of very tiny sacs called alveoli. Each alveolus is microscopic; but if we took all the alveoli in someone's lungs and laid them flat side by side we would end...
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