Background Information It is a known fact that all living cells must carry out respiration to

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Background Information It is a known fact that all living cells must carry out respiration to survive. There are two such forms of respiration. The first and most common form of respiration is known aerobic respiration, which is performed in the presence of oxygen. The other form of respiration is called anaerobic respiration. This particular method of respiration is far less efficient than aerobic respiration and is carried out only when the supply of O2 has depleted (or never existed initially). Aerobic respiration utilises the resulting product of glycolysis (which is pyruvate) in the Krebs cycle, also known as citric acid cycle, to create much more energy in the form of ATP (Adenosine Triphosphate) . The equation for aerobic…show more content…
However, without oxygen the pyruvates created during glycolysis are converted to lactic acid in animals and humans or ethanol in plants and yeast . Humans and animals utilise anaerobic respiration in situations of fast and high paced activities. An example of this is in a 100 metre sprint race or an animal being chased by its predator. In plants, when the presence of oxygen is minimal, anaerobic respiration is utilised. An example of this is the roots of plants in waterlogged areas where oxygen is minimal or absent. Yeasts are unicellular fungi that live on fruits, flowers and other sugar containing substrates. Yeast has a high threshold when it comes to a wide range of environmental conditions. Yeast serves a variety of purposing in everyday life. It is used for brewing beer, baking – particularly bread – and cheeses. Enzymes within the yeast break down the sugars such as fructose, glucose and sucrose to produce substances which permits the baking and brewing processes to work. Yeast can tolerate temperatures from freezing to about 55oC, pH levels between 2.8 and 8.0 and can even grow and ferment at sugar concentrations of 3M (high osmotic pressure) .
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