Cool Cellular Respiration Lab

In this lab, we measured the effect of various conditions (temperature and germination) on the cellular respiration of mung beans and peas. Cellular respiration occurs in living things according to the following formula: C6H12O6 + O2 = CO2 + H2O. Therefore, because O2 is in the reactants and CO2 is in the products, a decrease of the former and an increase of the latter indicates that cellular respiration is occurring. On the other hand, photosynthesis occurs in autotrophs according to the following formula: Light + CO2 + H2O = O2 + C6H12O6, so a decrease in CO2 and an increase in O2 indicates that photosynthesis is occurring.

In order to observe the effects of these various conditions on cellular respiration, we came up with several groups of peas and mung beans and used Vernier lab probes to create graphs of O2 and CO2 concentration. The groups were glass beads (used as a control group because no cellular respiration or photosynthesis should occur), non-germinating peas at room temperature, non-germinating mung beans at room temperature, germinating peas at room temperature, germinating mung beans at room temperature, germinating peas in ice water, and germinating mung beans in ice water.

We started things off with a control group for the experiment. This was done by placing glass beads in the container with the Verniers. The results show that there is no cellular respiration or photosynthesis going on since they are not living objects. The graph shows this by the straight constant line across the graph. There is an increasing slope but that is due to the Verniers adjusting to the conditions of the container. Overall, no increase or decrease in CO2 and O2 levels. 

In the first portion of the experiment, we tested the CO2 and O2 concentrations for the peas and mung beans at room temperature. 

Here are the results for the peas, with CO2 levels indicated by the red line and O2 indicated by the blue line.

And here are the results for the mung beans with O2 indicated by the red line and CO2 levels indicated by the blue line.

For both the peas and mung beans at room temperature, the O2 levels decreased and the CO2 levels increased, which means that for these plants at room temperature, cellular respiration was occurring. At what rate preceisely? For the peas, the CO2 concentration increased at a rate of .583 ppm/sec and the O2 decreased at a rate of .0002167%/sec. And for the mung beans, the CO2 concentration increased at a rate of .183 ppm/sec and the O2 decreased at a rate of 0.0002667%/sec. This tells us that cellulalar respiration occurred at a slightly faster rate in the peas than in the mung beans, and this makes sens, for the peas were larger and therefore have a greater surface area on which their stoma can open and close to facilitate the movement of CO2 and O2.

We then tested to see of the change in temperature of the peas and beans affected the levels of carbon dioxide and oxygen. First we soaked 25 peas in 100 milliliters of 9 degree celcius ice water  for ten minutes. 

Peas in ice water bath

Then we put the peas in the Vernier apparatus.

After ten minutes had elapsed this was how our data looked.

We then conducted the same procedures for mung beans. 

First by soaking 25 of them in the 9 degree celcius ice water for 10 minutes. 

Then placing them in the Vernier apparatus to measure the carbon dioxide and oxygen levels in the tank as 10 minutes elapse. 

Below is our data:

The conclusion that we can draw is that the chilled beans and peas both went through less cellular respiration. We can infer this because from the data we gathered from the probes, compared to the non chilled beans and peas earlier in this lab, the rate of carbon dioxide being produced is less and the amount of oxygen being used up is less. Carbon dioxide being one of the products of cellular respiration and oxygen being one of the compounds used up in cellular respiration. This explains how locations with colder climates experience less vegetation. In the case of no sunlight, cellular respiration kicks in, but as we have discovered in this lab, cellular respiration does not work well when subjected to colder environments. 

In this part of the experiment we tested dried mung beans and peas to test and see what type of reaction would occur. What we did was take 25 peas and 25 beans and put them in a container with O2 and CO2 sensors. We left them in there for ten minutes and then recorded the data and evaluated the graphs. 

In this picture we have the mung beans in a sealed container with the sensors.

Data we collected: 

These are graphs of the data that the sensors recoreded at room temperature

From this data we can tell that for dried mung beans the overall trend of O2 was decreasing and the overall trend of CO2 was increasing. In cellular respiration Oxygen is being absorbed and carbon dioxide is being released. The mung bean graph follows that trend and therefore we can conclude that the mung beans were preformed get cellular respiration.

In the peas graph the overall trend for O2 is increasing and the overall trend for CO2 is decreasing. This means that carbon dioxide is being absorbed and oxygen is being released. This pattern follows photosynthesis because carbon dioxide is absorbed and oxygen is released when water is split in order to feed electrons into the cytochrome complex.