Salivary Reactions and the Detection of Amylase, Lab Report Example

Research Question

Do human salivary reactions to food produce differing amounts of amylase depending on the age of the individual? To determine whether human salivary reactions to food produce differing amounts of amylase depending on the age of the individual, people of varying ages will be recruited and exposed to food via visual stimuli.

Background Information

People typically associate digestion with the concept of food degradation by bile in the intestines. However, the process of digestion begins in the mouth with the mechanical chewing of food. Although this mechanism appears to be purely physical, chemical digestion of food occurs in the mouth as well as the stomach. Amylase is an enzyme contained in saliva that is responsible for the breakdown of starch into sugars. Interestingly, the production of saliva is triggered when a person feels hungry or sees food (Maton et al., 1993). This response to visual stimuli helps the individual’s body become prepared for the digestion process.

The specific chemical mechanism that amylase used to break down starch is known as hydrolysis, which splits molecules by adding water to interfere with bonding. When amylase is added to starch and water, starch is converted into maltose (Maton et al., 1993). This chemical reaction works efficiently in the human body because this environment provides optimal heat for the catalysis.

It is known that the body’s metabolism slows down with age. However, this process is typically associated with a decrease in the speed of digestion in the intestine. Therefore, it would be useful to determine whether a decrease in metabolism results in a decrease of the ability for individuals to achieve proper mechanical digestion.

Hypothesis

If the ability of saliva to catalyze the reaction of starch into maltose decreases with age, the hypothesis that older individuals have a lesser capability to achieve mechanical digestion will be supported.

Variables

Independent Variable

The independent variable in this experiment is exposure of saliva of members of different age groups to starch.

Dependent Variable

The dependent variable in this experiment is the presence of amylase as measured by maltose detection via Benedict’s Solution. This will be quantified based on the color of the solution; a greenish precipitate indicates 0.5% concentration, yellow precipitate indicates 1% concentration, orange indicates 1.5% and red indicates 2% or higher concentration.

Control Variable (Constant)

The control variable in this experiment will be the addition of Benedict’s Solution to water (negative control) and the addition of Benedict’s Solution to a glucose solution (positive control).

Control of Variables

The same amount of saliva will be collected from each participant (1 mL), which will be repeated five times. Production of saliva will be stimulated by exposing participants to an aromatic cake. Equal amount of Benedict’s solution will be added to each sample (3 drops).

Materials

• Benedict’s solution
• 25x test tubes
• Test tube rack
• Cake
• Glass dropper
• 25x 1 mL pipette
• Pipetteman
• Baking starch powder

Method

Five participants were non-randomly recruited on the basis of their age. Two of the participants were young adults (ages 18 and 20), one participant was middle aged (51), and the two remaining participants were elderly (ages 65 and 70). The experiment was explain to the five participants to ensure consent. They were then exposed to the cake. Each participant was asked to salivate approximately 1 mL of fluid into 5 test tubes. To ensure the volume in each tube measured exactly 1 mL, the volume was measured using a 1 mL pipette. Excess saliva was removed from the test tubes.

Next, a pinch of baking starch powder was added to each tube and mixed well. Three drops of Benedict’s Solution were then added to each tube. The color of the reaction was observed and associated with maltose concentration (green – 0.5% concentration; yellow – 1% concentration, orange – 1.5% concentration, and red – 2% or higher concentration).

The average maltose concentration was determined for each participant. Descriptive statistics were measured to determine the central tendency of this data. The correlation of age and maltose concentration was then calculated using a Pearson correlation test. For the purpose of statistical testing, the spread of all data was assumed to be normal. To confirm whether there is an association between age and maltose concentration, a student’s t-test was performed; the maltose concentrations in the saliva of young adults was compared to the maltose concentration in the saliva of elderly adults. For all statistical tests, a p-value of 0.05 or less was considered statistically significant and all calculations was performed using Microsoft Excel. Lastly, a percent change calculation was performed to determine the extent of the increase in maltose concentration between the young adults and elderly adults. A percent change of greater than 5% was considered significant.

Data Collection and Processing

Raw Data

Table 1. Maltose concentration according to age

Processed Data

Table 2.  Average, standard deviation, mode, median, and range maltose concentration for each participant

Table 2 demonstrates that the maltose concentration was constant for each individual on study. Furthermore, both young adults exhibited a maltose concentration of 2%. Compared to the maltose concentrations exhibited by the older participants, it is clear that the young adults have the highest amylase activity. Since mean is equal to median and mode, this data is normally distributed. To determine the extent of the increase in maltose concentration between the young adults and elderly adults, percent change was calculated using the average maltose concentrations of each group (2% and 0.75%, respectively). It was found that there is a percent decrease in maltose concentration of -62.5% in the elderly adult group. Since this change is greater than 5%, it was considered to be significant.

To confirm whether there is an association between age and maltose concentration, a student’s t-test was performed; the maltose concentrations in the saliva of young adults was compared to the maltose concentration in the saliva of elderly adults. The null hypothesis was that the maltose concentration in the young adult and elderly adult groups would be equal. The p-value received was 0.13, indicating that the null hypothesis cannot be rejected and there is not a statistically significant difference between the maltose concentration in the saliva of young adults and elderly adults.

Conclusion and Evaluation

Conclusion

The results of this study support the hypothesis that Chlorophytum comosum is able to tolerate highly acidic environments. However, it was observed that the plant is able to tolerate basic environments as well. Despite the plant’s ability to tolerate growth in these pH ranges, it prefers a neutral pH. As the pH grew closer to 7, the ARG increased. Therefore, it is clear that pH impacts the plant’s metabolic activities. pH deactivates many key enzymes and proteins, which inhibits its ability to survive. Photosynthesis may be one of these processes due to its importance in ensuring plant survival.

Evaluation

A major limitation of this project was that it was not possible to explore the full range of pH. In addition to exploring the impact of ARG on the entire pH scale of 1 – 14, it would be valuable to examine growth trends more closely to a pH of seven by using pH increments of 0.5. In addition, the spider plant is a challenging organism to use for this type of study due to the presence of its many leaves. However, it was selected because compared to many other household plants, it grows quickly and is easy to maintain. If more time had been allowed for this project, it is likely that bamboo or a bonsai tree would have been chosen because growth can be more clearly measured.

Improvements

Several improvements can be made to the study. First of all, it would be helpful to use a larger sample size for each pH value examined. This would ensure that the recorded data has a greater ability to reflect the normal curve. In addition, it would be helpful to ensure the variables are controlled more tightly. One way to do this would be to remove the plants from natural sunlight and instead expose them to UV light so the exact amount of exposure could be fixed and recorded. Lastly, it would be useful to repeat this experiment on a variety of other plants to determine the pH environments they are capable of growing in. The results of this project would have useful implications in the field of agriculture.

The correlation of age and maltose concentration was calculated using a Pearson correlation test. Figure 1 depicts this data.

Figure 1. As age increases, the maltose concentration in saliva decreases

Figure 1 demonstrates that there is a negative relationship between age and maltose concentration. The coefficient of determination is 0.91 and the Pearson correlation coefficient is -0.95. Therefore, there is a strong negative correlation between age and maltose concentration.

Conclusion and Evaluation

Conclusion

The data indicates that there is a strong negative correlation between age and maltose concentration. In addition, there is a significant percent decrease in maltose concentration as age increases. Therefore, it is clear that amylase activity decreases as individual’s age and the decrease in metabolic rate experienced extends to chemical digestion in the mouth as well as in the intestine.

Evaluation

A limitation of this study is that amylase wasn’t measured directly. Rather, it was associated with the presence of maltose. While it may be feasible to study amylase directly in some settings, time and resources prevented this from occurring. In addition, all 5 of the saliva samples were collected on one day. As a consequence, no variability was observed. It may therefore be reasonable to repeat the study using saliva samples collected on 5 different days. However, the availability of the participants prevented this from occurring in this particular study.

Improvements

A major way that this study could be improved is by recruiting a larger group of people to ensure that multiple individuals in each age range is represented. A strong relationship was observed between maltose concentration in saliva and age, but this could have been biased by the small sample size. In addition, it may be beneficial to retrieve sample from individuals after they have eaten to determine if the concentration of amylase increases when a meal is physically consumed.

References

Maton A, Hopkins J, McLaughlin CW, Johnson S, Warner MQ, LaHart D, Wright JD. (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall.