The effect of temperature on the respiration rate in yeast I chose to investigate the effect that temperature has on the respiration rate in yeast. I will use an experiment to determine whether the yeast's respiration rate will be faster, slower, or not change as the temperature changes. Scientific Knowledge The first thing to say about enzymes is that they are proteins and are found in all types of organisms, from humans to viruses. They function in the body as catalysts. In other words they accelerate the speed of chemical reactions in the body. Enzymes actually speed up chemical reactions by a factor of about 1 million. Enzymes are organic catalysts. Without enzymes, an organism's metabolism would be too slow for the organism to survive. The word enzyme actually means "yeast" since they were first discovered in these microorganisms.------------------------------ - ---------------------------------------Enzymes are found inside and outside outside of the cells. The enzymes that are found outside the cells are, for example, those that control the metabolism while the enzymes that are found inside the cells, for example, the intestinal digestive juices and the enzymes secreted by bacteria, which digest food outside the body and then reabsorb the products. Enzymes work on particular organic chemicals, called substrates. Therefore food is the substrate of digestive enzymes.---------------------------------------- -- --------------------------The lock and key hypothesis attempts to explain how enzymes are specific to particular substrates and how they can work. In this hypothesis the enzyme is the lock and the substrate(s) is the key. Enzyme molecules have a particular shape like a lock and only a particular substrate (key) can fit into that lock. The part of the enzyme that binds the substrate is called the "active site". Just like other catalysts, after the enzyme has been involved in the reaction