Diffusion and Osmosis Lab Report Example | Topics and Well Written Essays - 1000 words

Diffusion and Osmosis - Lab Report Example One particular example is the absorption of water and other nutrients from the soil by root hairs in plants. The following experiments demonstrate these basic concepts in action, and how distribution of substances in two regions with different concenration gradients occurs. In order to determine osmolarity of a potato and how it is effected by the process of diffusion, a simple experiment is performed. 7 cylindars are carved out from a potato, and then cut to a uniform size of 5 cm. One very important aspect of this experiment are the 6 sucrose solutions, ranging from 0.1 to 0.6 molars, 100 ml each, and placed separately in 6 250-ml beakers together with 100 ml of distilled water. A sensitive balance is also necessary to accurately determine the weight of each potato piece, before and after incubation. Another experiment is performed to determine the process of osmosis. For this experiment a 500 ml beaker is used which is filled with 300 ml of water. A 25-30 cm dialysis tubing bag is essential, since it represents the semi-permiable membrane that is present during osmosis. 4 ml of a 30% glucose and starch (placed in the dialysis bag) and a small amount I2KI represent diffusing substances. Benedict's reagent is also necessary to determine the diffusion pattern of the substances involved. The carved out and cut pota... All the pieces are incubated for 45 minutes, and then their weights are measured and recorded. The percentage change in weight for each of the pieces is also calculated and recorded using the following formula: Percentage change in weigh= weight change/initial weight * 100 In the second experiment is prepared by soaking it in water, closing one end with a rubber band or string as not to let any solution to enter into the bag, and by adding a 4 ml of a 30% glucose solution into the bag. A 4 ml starch solution is also added, and the color of the glucose-starch solution is recorded. Then, 300 ml of distiled water is placed in a 500 ml beaker in which a small amount of I2KI is added. The color of this solution is also recoded. The dialysis bag is placed in the beaker and they are left for 45 minutes. It should be noted that the free end of the bag is not in contact with the solution of the beaker, as it is left lying out of the beaker. The color of both solutions (in the dialysis bag and beaker) are recorded, after which 3 ml samples are taken from each solution, as well as a sample of distilled water, representing the control tube. Placed in 3 different tubes, a small amount of Benedict's reagent is added to each tube. The final colors are then recorded. - Results Using the data collected from the first experiment, a graph can be plotted (Table 1). The y axis represents the osmolarities of the sucrose solutions, representing the independent variable while the x axis represents the weight of the potato pieces after incubation, represents the dependent variables, with the negative value being a decrease in potato piece weight, and vise

Implementing a taser program into a law enforcement agency Essay

Implementing a taser program into a law enforcement agency - Essay Example Taser stun guns have recently come under close scrutiny and critiscm because of the risks they pose to the public and their intended use. This has also been fuelled by the increased use of these devices, especially in the United States, and their intended use in the United Kingdom (Feakin 2007). Taser stun guns have been touted as the non-lethal alternative to deadly force and guns (Driscoll 2003, ACLU 2005), which has been viewed as an advantage when it comes to apprehending crime suspects, as it avoids needless deaths and injuries. However, there are figures which show that between 1999 and September 2004, approximately 71 individuals died in North America as a result of the use of the Taser stun gun (ACLU 2005). Whilst some may claim that these deaths are still less than those that come about as a result of the use lethal weapons, this still does raise some issues about whether Taser stun guns should be used at all, and if so, should their use be restricted to certain individuals. There are also figures which show that at the end of 2004, the fatalities from Taser stun guns had increased and there is evidence to suggest these deaths are a result of the incorrect or overuse of the device (ACLU 2005). For instance, there was an incident in the US where a young man was stunned for up to 17 times by the Taser stun guns (ACLU 2005) and this is thought to have contributed to the individual's death. Such incidences have most likely to have been the cause of the public concerns about this device, as it seems that the use of the Taser stun gun device is contributing to deaths, instead of preventing them. In addition to this, the manufacturers of the Taser stun gun have denied any claims that their device has directly contributed to the deaths of any individuals (Driscoll 2003, ACLU 2005). Despite these safety concerns, the appeal of the Taser stun gun to law enforcement agencies worldwide is appealing. For instance, law enforcement agencies in the UK, do not carry guns and the purchase and use of Taser stun guns is highly attractive as an alternative to considering lethal devices. In the US, law enforcement agencies already carry lethal devices and Taser stun guns are an attractive option to counter-act concerns regarding the deaths of innocent civilians caught in the cross-fire or in instances of mistaken identity. However, the concerns over the current use of Taser stun guns seem to be related to their application and over-use of the device. This has been acknowledged by the International Association of Chiefs of Policy (IACP) which has recommended the re-evaluation of Taser training and the establishment of policies (ACLU 2005), to minimise the deaths from the use of this device. This acknowledgement from the IACP does recognise that the use of t