An Experiment to Show the Rate of Respiration In a Locust.

Diagram

Results

Discussion

Respiration provides the necessary energy for carrying on all essential life processes. Respiration is divided into two distinct phases; external respiration and internal, or cellular respiration. External respiration includes all steps in the process of delivering oxygen to each cell in the body and disposing of carbon dioxide, a gas given off as a waste product when cells use up oxygen. In humans and other animals such as locusts, that have lungs (or equivalent of), breathing is an essential part of external respiration. Internal respiration occurs inside every living cell and involves a series of chemical reactions that liberate energy from food. Some of the energy is transformed into body heat while the rest is used to drive other chemical processes that keep the body working. During internal respiration in animals, food molecules are usually combined with oxygen and carbon dioxide is usually released. The rate of respiration in cells and tissues is directly related to the demand for energy. When cells are in a growth phase or involved in protein synthesis, for example, their rate of respiration is high. In dormant tissues the rate of respiration is minimal.

From looking at my graph generally I can see that the rate of respiration increases gradually. However by looking at my results table closely, I can see that the variations in rates of respiration are not too dramatic; the lowest rate being 0.25 and the highest being 1. The average rate of respiration is calculated by working out the gradient of the line, which in this case proves to be 0.06. The reason for the difference in rates of respiration at different times would be down to the fact that the locust would not have acclimatized (perhaps because of fear, claustrophobia or both) and therefore would have been breathing faster at some times and slower at others, this therefore would cause a higher rate of respiration at some points and lower at others.

An increase in the temperature from 37°C to 60°C would cause the metabolism of a locust to speed up. The reason for this is that Locusts are poikilothermic animals, which means that the environment they are in controls their body temperature. If they are placed in a warm environment then they become warm and so do their cells. This speeds up their metabolism (the chemical reactions taking place inside their body) including the rate at which they respire. Therefore the respiration rate increases because the locust's body requires more oxygen in order for its metabolism to speed up. Therefore an increase in the temperature would cause an increase in the rate of respiration of a locust.

 A lot of things could have been done to reduce anomalies in this experiment. One thing I could have done to make it more reliable was to weight the soda lime and use the same amount in each test tube –as they could have been different amounts. Another was making sure that the marble I used was the same volume as the locust (which would be very difficult to do in class). Another major anomaly could have been in assuming that the respiration of the locust would be normal after a certain period of time after it had acclimatized; being realistic this would not be the case, as realistically, the locust would have had a higher rate of respiration during the whole experiment, and therefore would not have acclimatized so quickly-or maybe not at all during the whole experiment.