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Effect of Heat on Respiration Rates

Introduction: All living things require energy in carrying out activities. The process by which energy is made available from nutrient of cells is called cellular respiration. Cellular respiration is the controlled release of energy, in the form of ATP from organic compounds in cells.
Respiration occur under two conditions which is with the presence of oxygen and without the presence of oxygen. If there is presence of oxygen, then the process is called aerobic respiration. However, if there is lack or absence of oxygen, then it will refer as anaerobic respiration.
Respiration involves enzyme that can be affected by the temperature. The rate of the respiration increase with the increase in temperature until it reaches the optimum temperature. This is where the rate of the respiration is the highest. Further increase in temperature only lowered the activity of the enzyme as it begins to denature.
Research Question: How does the temperature affect the rate of respiration?
Objective: Investigate the effect of heat towards the rate of respiration of Mung beans.
Hypothesis: The rate of respiration increases with the increase in temperature. This will continue until it reaches 60oC where the rate of respiration is the highest.
Variables: Variables Range Unit Ways of controlling Independent: Temperature of the solution with the mung beans
300C,400C,500C and 600C
The mung beans and the Bromcresol solution is put inside water bath with temperature 300C until it reaches they reach the temperature. Then, the mung beans are put inside the Bromcresol solution. The experiment is then repeated replacing the temperature to be 400C, 500C and 600C.
Dependent: Time taken for Bromcresol solution to change from purple to yellowish colour.
– Minutes and seconds (mins:s)
The time taken for the Bromcresol solution to change from purple to yellowish colour is measured using a digital stopwatch and recorded for every repeated experiment.
Controlled Variables Unit Ways of controlling Possible effects on result Mass of mung beans
100g of mung beans is measured using electronic balance and is used in every repeated experiment.
With the same number of mung beans, comparison between every repeated experiment can be made easily as the amount of the mung beans is the same by controlling its mass. If the mass is varied, the result will be hard to compare with the other.
Types of beans used
– Mung beans is used for every repeated experiment.
The same type of beans will ensure the equality of each experiment and enable comparison of results obtained from the experiments. Different type of beans may respire with different rate and affect the result of the experiment.
Volume of Bromcresol
6 drops of Bromcresol is added using a dropper in the preparation of the indicator solution.
Bromcresol is used to detect the presence of carbon dioxide. With the increase of number of drops of bromcresol, the experiment will take more time for the reaction to occur. 6 drops of bromcresol ensures the experiment can be completed in the given time period.
Materials Procedure: a) Prepare the indicator solution
50ml of tap water was added into a beaker, and then 6 drops of Bromocresol purple solution was added.
The colour of the solution changed to purple.
b) Prepare the standard solution
10 ml of the indicator solution was transferred from the beaker into a test tube.
Expiring gas is blown into the solution using a straw. The solution changes colour from purple to greenish.
This was used as standard solution.
c) Conducting the experiment
The outer skin mung beans were peeled and the mung beans are put in a beaker. 100g of the beans is measured and put in a test tube.
10 ml of the indicator solution was added into the test tube. The test tube containing mung beans is then put inside a water bath of 300C.
The temperature of the test tube is recorded and maintained using a thermometer.
Once in a while, the test tube was shaken and the time taken for the solution to change colour from purple to yellow as the standard solution was recorded using a digital stopwatch.
The experiment was repeated by changing the temperature (400C, 500C and 600C) respectively. It was controlled that the temperature of the mung beans and the solution while in the water bath reaches the temperature needed before adding both together.
The time taken for the colour to change for all different temperature is recorded suing a digital stopwatch.
Data collection: Quantitative data:
oC ± 0.05oC
Time taken for solution indicator to change to yellowish colour, minutes and seconds ±0.001seconds

Qualitative data:
When the indicator solution is added into the test tube containing the mung beans, the colour of the solution is purple.
After a few minutes, the colour of the solution changes from purple to yellow. In the room temperature, 30 oC, the test tube feels warm.
Table 1.2 – Shows The Qualitative data obtained by observation at initial and final result.
Data processing and analysis Changing the unit of minutes and seconds into seconds For the ease of calculations, the unit of time is changed to seconds. To change the unit of minutes and seconds into seconds we can use the following formula:
As an example, in trial 1at 30oC, the time taken was 14:40 minutes. To change the unit into seconds, the calculation is:
(14×60) 40 = 880 seconds.
The calculations for other temperature are tabulated in the table below:
oC ± 0.05oC
Time taken for solution indicator to change to yellowish colour, seconds ±0.001seconds

Calculating the average time taken for each temperature. Average time taken is calculated to find the mean of the time taken for the solution to change to yellow from purple. The average time taken for each temperature is calculated by using the following formula:
As example of the calculations, the average time taken for the purple colour of indicator solution to turn to light yellow colour at 30oC :
= 776 seconds
Therefore, the average time taken for the purple colour of indicator to turn to yellow at 30oC is 776 seconds.
oC ± 0.05oC
Time taken for solution indicator to change to yellowish colour, seconds ±0.001seconds

The uncertainty of average time taken. To calculate the uncertainty for the average time taken, we can use the formula of standard deviation:
sd= ;
sd= Standard Deviation
∆= uncertainty
mean= average time taken
x= time taken
n= number of trial
As an example, below is the calculation for the experiment at temperature of 30oC where the average time taken is 776.00:
Temperature oC Trial x (x-mean)2 30
Table 2.3 – calculation for the experiment at temperature of 30oC
For the other value, the calculation is made and is tabulated in the following table:
oC ± 0.05oC
Time taken for solution indicator to change to yellowish colour, seconds ±0.001seconds
Average time taken, seconds

Rate of respiration After obtaining the average time taken, we can easily calculate the rate of respiration of the beans. Rate of respiration is calculated by using the formula of:
As an example, at 30°C, the rate or respiration is:
= 0.001289 s-1
Therefore, the rate of respiration at 30°C is 0.001289 s-1. Table below shows the calculation for the other values:
oC ± 0.05°C
Average time taken, seconds
Uncertainty of average time taken, seconds.

Uncertainty of rate of respiration The uncertainty of the rate of respiration can be calculated after obtaining the rate of respiration itself. To calculate the uncertainty of rate of respiration, the formula is:
∆R = x R
R = Rate of time taken
t = time taken
∆ = uncertainty
At 30°C, the rate of respiration is 0.001289 s-1. The uncertainty of rate of respiration is calculated as example below:
∆R = x 0.001289
= 0.0002804 s-1
Therefore, the rate of respiration at 30°C is 0.001289 s-1 ±0.0002804 s-1 .
The following table shows the rate of respiration of the mung beans for every temperature:
oC ± 0.05°C
Average time taken, seconds
Uncertainty of average time taken, seconds.
Rate of respiration, s-1
Uncertainty of rate of respiration, s-1

Based on table 2.6, the graph of rate of respiration against temperature can be plotted.
Discussions: Theoretically, the rate of respiration increase when the temperature increase until it reaches optimum temperature. At the optimum temperature, the rate of respiration is at the highest. After that, the rate of respiration will drop due to the denatured of the enzyme that involve in respiration.
But after the experiment is done, the results obtained shows that the rate of respiration keeps increasing till 60oC. We can say based on our experiment, the optimum temperature for the respiration of mung beans is more than 60oC.
The error is too small to be shown on the graph. This is because less error is being put in doing the experiment and safety precaution is taken.
The rate of respiration increases as the temperature increases until it reaches optimum temperature. Enzyme works efficiently at higher temperature because high energy is required for the enzyme undergoes the effective collision with the substrate frequently.
The Bromcresol solution function is to determine the existence of carbon dioxide gas in the air. If there is carbon dioxide gas, it will change colour from dark brown to yellow. So, time taken for the solution to change colour can be used up to measure the rate of respiration.
Limitations and suggestions
1. It is difficult to maintain the temperature of the test tube in 60°C as there is no electronic water bath is available.
Suggestion: The water for 60°C should be added so that it is easier for the students to maintain the experiment at 60°C rather than having their own water bath using Bunsen burner and beaker.
2. The exposure of the bromcresol solution to the surrounding may affect its reliability as an indicator. Some carbon dioxide gas from human respiration will affect the colour of the indicator.
Suggestion: The test tube that contains the bromcresol solution must be closed by using rubber stopper at all times.
3. The usage of distilled water in preparing the indicator solution is not suitable as the solution will be yellow when added with bromcresol.
Suggestion: Students should be aware of different situations of different solution and advised to use tap water in similar upcoming experiments
Conclusion The rate of respiration increases with the increase in temperature. This will continue until it reaches 60oC where the rate of respiration is the highest. From this experiment, the optimum temperature of the respiration of the mung beans is 60oC. Hypothesis is accepted.

Intestinal Parasites in HIV/AIDS Patients

The introduction of antiretroviral therapy has lessened the prevalence of gastrointestinal infections in HIV patients, this notwithstanding, several people with HIV infection still suffer from intestinal parasitosis [20]. Co-infections of intestinal parasitosis found among HIV patients from low income countries has been anything from 18% to 50% [5-7]. In the current study, an overall prevalence of intestinal parasite among the study population was 19.3%. However, the prevalence of intestinal parasites in the HIV seropositive group was significantly higher (25%) than that observed in the HIV seronegative group (13.3%). The observed prevalence in this study is similar to others carried out in Zambia which reported 25% prevalence among HIV-infected cohort [21]. Other reports from India, Ethiopia and Tanzania were comparably higher ranging from 30% and above [22, 23]. However, much lower prevalence of 10.6% among HIV patients have also been reported elsewhere [24]. The occurrence of intestinal parasitic infection did not differ in respect of rural or peri-urban setting. However, infections with Cryptosporidium in this study were significantly associated with the rural cohort. Cryptosporidiosis causes prolonged bulky and sporadic diarrhea in AIDS patients, with liquid non-bloody stools, together with pains and abdominal colic, and concomitant weight loss [25]. Contaminated drinking water, foodstuffs and contact with infected animals are risk factors for the transmission of intestinal parasitosis; the fact that coccidian parasites were significantly higher within the rural cohort may be attributed to unfavorable socioeconomic conditions, lifestyle as well as relatively poor sanitation that is endemic in the rural dwellings. These may be the same risk factors sustaining intestinal parasitosis at high prevalence in the developing world. It was also observed that opportunistic parasitic infections mainly the coccidian parasites occurred exclusively in HIV/AIDS patients with a corresponding depletion of CD4 T- cell count. This has been attributed to the modulation of immune response in the advance stages of the disease [8]. The highest prevalence of parasitosis was observed among participants in the CD4 T-cell level ≤50 cells/µl. This category forms 56.5% of participants in the advanced stage of the disease. The most predominant parasites recovered among this group of participants belonged to the coccidian groups (47.8%) which are well known as opportunistic parasites in HIV disease. With the exception of one participant, all participants that had mixed parasitic infections had CD4 T-lymphocyte count of less than 200cells/µl. This observation has been echoed by other studies [6, 26]. Typically, the dynamics of HIV-1 infection is known to follow a familiar pattern where there is the acute phase in which, there is massive depletion of CD4 T cells of the gastrointestinal tract [27], after which there is the chronic phase, where there is a gradual reduction in CD4 T cells which results in heightened risk of opportunistic infections and then AIDS sets in. Recently it has been found that there is significant preferential loss of Th17 cells in the GI tract of HIV-infected patients [28] which is as a result of microbial translocation after the initial structural and immunological disruption of the gut mucosa in the acute phase [29].
The prevalence of G. lamblia was the highest and most common parasite among the participants. Its occurrence, among both HIV seropositive (11.4%) and seronegative (11.8%) was similar. Previous studies have demonstrated that although infection with Giardia lamblia and HIV correlated with enteritis or enterocolitis, its incidence does not differ amongst HIV-positive and negative patient populations [30, 31]. This underscores the non opportunistic nature of the G. lamblia reviewed by Cimerman et al. [32].
The helminthes observed in this study were A. lumbricoides, E. vermicularis, Hookworm and S. stercoralis. Helminthes infections generally were low among the study groups when compared to findings of similar studies elsewhere reporting prevalence of 37.04% [33]. However, S. stercoralis was only associated with HIV seropositive individuals where mixed infections of S. stercoralis and Hookworm infections were higher. Modjarrad et al. (2005) reported relatively higher prevalence of intestinal helminthes (24.9%) with A. lumbricoides and hookworm being prevalent among HIV-1 patients in an urban African setting [34]. Apart from S. stercoralis, other helminthes had lower prevalence in our study when compared to others carried out in similar developing countries [22]; this may be due to the widespread administration of anti-helminthes and cotri-moxazole among the study participants.
Studies have shown that, reconstitution of the immune system following ART administration alone resolves Cryptosporidium infections without specific treatment for the parasite [22, 35, 36]. This is because ART acts against the aspartyl-protease of the parasite depriving the parasite of an essential protein [35, 36]. More than 56% of participants were already on ART at the time of stool collection. It is likely that as patients CD4 T-cell level increases with the administration of ART, opportunistic infections are not established even if they are exposed to infection.
Diarrhea is a life threatening complication often associated with HIV causing severe weight loss; both of which are independent predictors of mortality in HIV/AIDS [13, 37]. The incidence of diarrhea among HIV seropositives was significantly higher, where 32.7% of them had diarrhea irrespective of parasitosis (Table 5). Diarrhea among HIV participants increased with decreasing CD4 T-cell count with the highest number of diarrhea participants (78.3%) occurring at the CD4 T-cell count < 50cells/µl and the lowest (2%) was found in participants with CD4 T-cell count of ≥500cells/µl (Table 5). G. lamblia, I. belli, Cryptosporidium, and S. stercoralis were associated with diarrheal stools of HIV seropositive patients (Table 4). Among the opportunistic coccidian parasites in HIV seropositives I. belli (3.5%) was predominant followed by Cryptosporidium (2.1%). Microsporidia and C. cayetanensis had a prevalence of 0.9% and 0.3% respectively occurring exclusively among HIV seropositives. All participants with I. belli infections presented with diarrhea. This strong association with diarrhea may be associated with patients who were ART naïve who presented very late to the hospitals with wasting, general weakness and diarrhea. Cyclospora cayetanensis; an emerging parasite, was found in only one participant with diarrhea.
The presence of diarrhea without parasites in stool could be from bacteria etiology, lactose intolerance or insufficient sensitivity of the diagnostic procedure [38, 39]. It has been shown however, that no etiological agent is found in 15-50% of HIV patients with chronic diarrhea [38, 39]. Munnink et al., (2014), observed that unexplained diarrhea in HIV- infected patients were not due to novel pathogens [immunodeficiency-associated stool virus (IASvirus)] [40] or previously unknown pathogens, but may be due to HIV-1 itself having a “virotoxic” effect on the enterocytes that results in intestinal mucosal abnormalities leading to diarrhea [39]. These factors may explain the significantly higher prevalence of diarrhea in HIV seropositive participants. It is thus conceivable to state that the interpretation of diarrhea associated with parasitic infections must be made cautiously.
In spite of the high prevalence (25%) of intestinal parasitosis in HIV patients, there are currently no clear guidelines that require its diagnosis. Moreover, the high burden of intestinal parasitosis results in diarrhea and weight loss which are independent predictors of mortality in HIV patients. In order for HIV patients to obtain comprehensive healthcare, it is recommended that efforts are made towards diagnosing intestinal parasites in HIV patients especially those with CD4 T cell counts less than 50cells/µl.