cellular respiration

Extended Experimental Investigation

Respiration

Introduction:

All living things respire. In fact, respiration is one of the most basic characteristics of living organisms so that if an object does not respire, it’s not considered living. Respiration involves a complex series of chemical reactions where sugars are broken down to release energy by the use of oxygen.

Respiration is the energy producing process of breathing, by which an organism supplies its cells with oxygen and relieves itself of carbon dioxide. The most effective way for cells to harvest energy stored in food is through cellular respiration, which is a metabolic process that captures the chemical energy from foods and converts them into ATP. The energy required to power living cells comes from the sun; plants capture this energy and convert it to organic molecules.

In respiration, plants and animals convert glucose back into energy for growth. The chemical equation shows that the photosynthates from photosynthesis are combined with oxygen. The chemical equation for the process of respiration is:

C6H12O6 + 6O2 ←➔ 6CO2 + 6H2O + energy

The process is similar to the oxidation that occurs when wood is burned, producing heat. When compounds combine with oxygen, the process is referred to burning. Respiration is the burning of photosynthates for energy to grow and to do the internal work of living. It’s important to know that both plants and animals need oxygen for respiration. This is why saturated soils are detrimental to both root growth and function, as well as the decomposition processes in the soil.

In Photosynthesis, carbon dioxide from the air and water makes the soil react with the suns energy to form photosynthates such as sugars, starches, carbohydrates and proteins. Photosynthesis means, ”to put together with light”. The rate of photosynthesis is somewhat dependant on temperature. The chemical equation for the process of photosynthesis is:

6CO2 + 6H2O + light ←➔ C6H12O6 + 6O2

Notice that the equation for respiration is the opposite of that for photosynthesis

Comparison of photosynthesis and respiration

Photosynthesis Respiration

Produces sugars from energy Burns sugars for energy

Energy is stored Energy is released

Occurs only in cells with chloroplasts Occurs in most cells

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Oxygen is produced Oxygen is used

Water is used Water is produced

Carbon dioxide is used Carbon dioxide is produced

Requires light Occurs in dark and light

Cellular respiration allows organisms to use (release) in the chemical bonds of glucose (C6H12O6). Glucose is broken down to yield carbon dioxide and water, and the energy from this process is stored as ATP molecules.

There are two different types of plant respiration:

Respiration during photosynthesis
Respiration whilst germination

Germination is the process whereby a seed emerges from a period of ...

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Oxygen is produced Oxygen is used

Water is used Water is produced

Carbon dioxide is used Carbon dioxide is produced

Requires light Occurs in dark and light

There are two different types of plant respiration:

Respiration during photosynthesis
Respiration whilst germination

Germination is the process whereby a seed emerges from a period of dormancy. Most seeds go through a period where there is no active growth. Germination is the point when the seeds start growing, developing roots and shoots. When a plant seed is germinating, it means it’s growing and as it grows there is an increase in the need of 02.

As a seed keeps germinating eventually the rate of respiration slows down, the germinated seed is at its peak when the sprout pierces through the shell, at this stage the rate of respiration dramatically increases, the seed requires much more energy so the sprout can pierce through the shell and start growing.

Aim:

To determine whether germinating and non-germinating mung beans respire at different rates at different germination stages.

Hypothesis:

The mung beans will respire at a rapid rate in the earlier stages of germination and then the rate of respiration will slow down.

Method:

Method 1- germinating mungbeans (preparation)

Step 1: experimenting over five days which meant we needed to germinate five days worth of mungbeans (150mung beans allowing some don’t germinate)

Step 2: 150 mung beans placed onto styra foam tray which was layered with 4 layers of paper towel. The mung beans were watered down then another piece of wet paper towel was placed over the top. The water was then drained from the styra foam tray. All that is left in the styra foam tray is saturated mung beans and paper towel.

Step 3: Now that the mung beans have been prepped, they are placed in the incubator at 30oc heat.

Now the preparation of the mungbeans is complete the preparation and setting up of the experiment can occur.

Method 2 – Experimental procedure

Step 1: All materials which were needed to perform experiment were listed down and provided by a lab assistant

Step 2: A stand and clamp was needed to be set up in order to hold the test tube in place.

Step 3: One test tube was used in order to fulfill the experiment.

Step 4: Soda lime(lime chips) were placed in the bottom of the test tube in order to absorb the existing CO2 in the test tube. Soda lime is made up of a mixture of sodium and calcium hydroxides X. The soda lime in this experiment is used to absorb the existing CO2 in the test tube

Step 5: After the soda lime was placed in the test tube a layer of non absorbent cotton wool was placed on top, this was just to hold the mung beans in place; the non-absorbent cotton wool would not affect the experiment as it was non-absorbent

Step 6: The 20 mung beans were then placed in the test tube

Step 7: Another layer of non-absorbent cotton wool was layered over the mung beans, again to keep them in place

Step 8: The rubber stopper with the graduated pipette and the syringe was firmly pressed into the test tube so that air could not get in or out via spaces in between the stopper

Step 9: The test tube was then placed in the stand and clamp and tilted horizontally

Step 10: The experiment was then left for 5 minutes for the soda lime to absorb the existing CO2 in the test tube

Step 11: After the 5 minutes was up a small amount of red die was sucked up into the pipette by using the syringe

Step 12: The red die would then move down the test tube indicating the respiration of the mung beans

Step 13: After 5 minute intervals results on how far the red dye had moved were recorded

Step 14: Steps 2-13 were repeated until all appropriate experiments were performed

(Source: John Miller)

Safety:

During the experiment, there were very little safety requirements. Before any experiments were undertaken, risks assessments were to be completed and handed in. Normal lab procedures are to be followed such as wearing safety glasses, safety gloves, shoes ect. The main safety precaution was the soda lime (mixture of calcium hydroxide and sodium hydroxide), which is a strong base and will cause irritation and burns upon contact with skin. If you come in contact with soda lime, thoroughly wash with soap for 5 minutes and alert nearby teacher.

Results:

Graph1. Results showing the amount of respiration in mung beans over 5 minute intervals

Discussion:

During this experiment, we were to determine whether germinating and non-germinating mungbeans respire at different rates at different germination stages. Throughout the period of time given, tests were set up over 5 minute intervals to measure the respiration rate of mungbeans in different germination periods.

From the table are graph above, you can see that the rate of respiration fluctuates as the mung beans goes throughout the different stages of germination. From these results you can see that the mung beans have a slow respiration rate as they are non-germinated and a faster respiration rate as they are germinating. This was expected as mung beans respire at different rates throughout different germination stages.

Our experiment supported the hypothesis that the mung beans would respire at a rapid rate in the earlier stages of germination then the rate of respiration would slow down. Evidence of this is shown on the graph as the one day old germinated mung beans respiration rate rapidly speeds up. These results were supported by my background information as the respiration rate of the mung beans rapidly increases at the start of the germination period, this is because the seeds are at the most rapid transformation as the sprouts pierces and penetrates through the shell. This dramatic increase in the respiration rate is due to the fact that the mung beans require much more energy so that the sprouts can pierce through the shell.

As the respiration rate starts to slow down at around day four, background information and my hypothesis are again supported. On the fourth and fifth and day of germination, there is a decrease the mung beans respiration rates, from the background information stated, most seeds go through a period where there is no active growth and another reason as to why there is a decrease is because all the energy was used in order for the bean to fist pierce through the shell.

The results obtained from this experiment show that the one day old germinated mung beans had the fastest rate of respiration 2.25cm (every 5 minutes), this was expected due to the seeds having to use a lot of energy in order to pierce through the seeds shell. The fifth day of germination showed the lowest respiration rate of 1.17cm (every 5 minutes), this was due to photosynthesis and the stage of no active growth. The non-germinated mung beans had a slow respiration rate of an average 1.4cm (every 5 minutes), which was expected due to the mung beans being dormant when they are non-germinated.

Error Analysis:

Throughout the experiment our group was met with some factors in which our method itself resulted in a variety of results on day 1. After the very first test 1, because of a measurement problem in which the dye was moving faster then we intended, we had to suck the dye back into the correct place resulting in the rubber stopper popping of the test tube. In doing this, CO2 was introduced back into the test tube. Before starting the second test we forgot to let out the existing CO2, which therefore impacted on the results. If we had waited for 5 minutes to let the existing CO2 out, our results may have been more accurate. Because of these mistakes, we decided that we would not reset the graduated pipette until these results we needed were recorded.

Along with this, another problem was that when the dye in the pipette, which was a measure of the respiration rate, was not frequently changed, it separated and was also moved to far along the pipette. Because this was happening, we had try and suck more die up the pipette but in doing this, bubbles of CO2 were sucked back into the pipette along with the dye meaning the results were effected as more CO2 was introduced.

Conclusion:

In conclusion