Limon Trust: November 2013

Introduction: In this lab, we tested the effects of temperature as well as germination on the respiration of the barley seed. A plant is a living thing and needs energy to survive much like humans. When a plant undergoes cell respiration, it is using it's stored energy in the form of a sugar along with oxygen that's in the air to form water, CO2, and usable energy.

The equation is as follows: C6H12O6 + O6 → CO2 + H2O + Energy

As you can see, the hooded part is a 6 carbon sugar which is combined with oxygen yields carbon dioxide and water and usable energy.

That usable energy is then consumed by primary consumers which pass on a fraction of the primary energy it used to consume the plant out into the universe, creating entropy. When the barley seed is germinated, it means that it is ready to grow. The dormant stage of the seed is over and it begins to jettison extremities which require respiration. These extremities could be premature roots, leaves etc. So the question is, does the seed produce the most CO2 (respire the most) when it's non-germinated (dry and dormant), when the seed is germinated at room temperature, or when it's germinated and stored at a cold temperature.

Procedure: First we obtained the temperature of the room using a thermometer. Next we obtained 25 germinated barley seeds at room temperature and placed them in the respiration chamber. We placed the CO2 gas sensor in the chamber, sealed airtight. After a minute we started the CO2 gas sensor recording. After 10 minutes we stopped the recording and removed the CO2 gas sensor as well as the seeds. The seeds were placed in a beaker filled with ice cubes and water. The temperature of the ice water was recorded using a thermometer. We allowed soaking for 10 minutes. In the meantime we placed non germinated barley seeds in the respiration chamber following the same procedure to record CO2 gas emission. After 10 minutes we removed non germinated seeds and replaced them with the cold water germinated seeds that had been soaking. This was recorded for 10 minutes again using same procedure. Lastly we placed glass beads in the respiration chamber and recorded respiration.

Methods: By taking the temperature of the room we could determine the temperature at which the barley seeds were germinated. The CO2 gas sensor was sealed tightly to create a closed system and prevent gas exchange. By recording the CO2 gas in the respiration chamber we could determine the respiration of the room temperature germinated barley seeds. We placed the germinated barley seeds in cold water immediately after to allow time for the seeds to become as cold as possible. Recording the temperature of the cold water will help distinguish between cold germinated seeds and the warmer room temperature germinated seeds. Recording Non germinated barley seeds' respiration created a control group. Taking the respiration of the glass beads proved the validity of the respiration chamber using gas sensor.

Discussion: An immediate improvement that can be made to the experiment is letting the cold seeds rest in an ice bath while taking the CO2 reading. We could have let the container with the barley seeds along with the sensor sit in an ice bath. This would prevent the seeds from getting back into room temperature and would improve the reading of the cooled CO2.

This did not sway the graphs too off tilt and the data was similar across the board. Every groups graph showed a higher emission of CO2 in germinated seeds at room temperature, and lower CO2 emission in non germinated as wells as the cooled barley seeds. The trend makes sense because of the structure of the seeds. The germinating seeds need to make more energy to grow. Thus, they respire more and emit more CO2 than the dormant and and cooled barley seeds.

The rate of respiration was the highest in the pea seeds and the lowest in barley seeds. This is possible because of the chemical makeup and energy requirements for germination of the particular seeds.

Graphs & Data:

Room temp non germinated

Room Temp. Germined

Cooled Non germinated barley

Glass Beads (control for CO2 activity)

Class data

CO2 recording apparatus with dry barley

Germinated barley (note the extremities)

Glass beads for control group

Germinated seeds that yielded the most CO2

Conclusion: This lab proved that germinated barley seeds at room temperature release more CO2; therefore, they respire more than non-germinated seeds and germinated seeds at cold temperature. Even though the respiration rate of the cold germinated seeds and the room temp seeds was somewhat close, it is proven that barley seeds have an optimal temperature at which they respire the most. In this experiment, the seed respired less at a cold temperature, even less when it’s dry and dormant, and the most when its moist and at room temperature.

Introduction

In this lab we studied the effects of enzymes and their effect on various substances. An enzyme is a naturally occurring particle that speeds up a reaction. The enzyme takes in the reactants, adds a phosphor ion to the reactant, thus motivating it to do work with less activation energy. The overall release of free energy is the same even with the presence of the enzyme, which makes enzymes nifty. The substrate is the substance the enzyme acts upon. In this case, it was the yeast and the hydrogen peroxide. In this procedure, we tested for the concentration of hydrogen peroxide with an indicator KMO3.

Enzymes function at optimal temperatures and optimal pH levels. At an optimal temperature, the rate of the reaction is the highest. At optimal pH, the reaction rate is also the highest. In this experiment we conducted a test for optimal pH and see how the enzyme would react if we injected acid into the solution.

Also present in this experiment are catalysts. A catalyst is, in this case, a substance that affects the rate of the reaction. A catalyst can either inhibit or increase the reaction rate by lowering the activation energy. An enzyme is just a type of catalyst.

Procedure

Baseline) First we added 10 mL of 1.5% hydrogen peroxide solution to a beaker. We then added 1 mL of water instead of enzyme solution. After we added 10 mL of sulfuric acid to stop the reaction. We removed a 5 mL sample of the solution into another beaker. We added Potassium permanganate to the solution drop by drop until solution remained a pinkish color.

Uncatalyzed hydrogen peroxide reaction) Here we placed about 15 mL of 1.5% hydrogen peroxide solution in a beaker. We let it sit overnight. The following day we added sulfuric acid to the solution. We took a 5 mL sample and added potassium permanganate drop by drop until a pinkish color remained.

Enzyme catalyzed hydrogen peroxide reaction) Here we placed 10 mL of 1.5% hydrogen peroxide solution in each of 6 beakers. We added an enzyme to each solution in this case yeast. We let each beaker sit for 10, 30, 60, 90, 120, 180, 360 seconds respectively. We added sulfuric acid after time was up for each beaker. Then we took a 5 mL sample from each beaker and added potassium permanganate drop by drop using a burette until the solution for each beaker remained pink.

Methods

Baseline) First we established a base line. Without adding catalase to the Hydrogen peroxide solution, instead water we could more easily determine the amount of hydrogen peroxide present at the beginning of the reaction. By adding the sulfuric acid it would stop any spontaneous reaction from proceeding. By taking a sample and then adding potassium permanganate we can determine the amount of hydrogen peroxide present after the reaction has stopped. The amount of potassium permanganate added is proportional to the amount of hydrogen peroxide present. When the solution turns pinkish it represents a bit leftover of potassium permanganate that did not dissolve hydrogen peroxide.

Uncatalyzed hydrogen peroxide reaction) We left a solution of hydrogen peroxide overnight without adding a catalase to determine the rate of a spontaneous reaction. The conversion of hydrogen peroxide to water and oxygen. The next day we added sulfuric acid as it stops the reaction. We took a sample and added potassium permanganate to determine the amount of hydrogen peroxide that did not react or decompose into water and oxygen. This part showed the rate of an uncatalyzed hydrogen peroxide solution decomposition.

Enzyme catalyzed hydrogen peroxide reaction) The yeast added to each solution was the enzyme that will speed the reaction or decomposition of hydrogen peroxide to water and oxygen. And each beaker was left to proceed in its reaction for differing times before sulfuric acid was added to stop the reaction. After we took samples of each of the differing time beakers and added potassium permanganate to determine the amount of hydrogen peroxide that was left. This part gave showed the amount of hydrogen peroxide left after being catalyzed by yeast at differing times in this case 10,30,60,90,120,180,360 seconds.

Discussion

Some mistakes will be accounted for in this part of the lab. As you can see, our data does not correspond with the purpose of the lab. Our data table should have shown an inverse relationship between the time and the amount of KO4 we used in our experiment. This only happens from second 60 to 90 and then from second 180 to 360. The increasing amounts should have been higher than its preceding ml of KO4. We assumed that inaccurate samples were taken of the substances. For example, we might have taken a 10 ml sample rather than a 5 ml sample.

However, other groups have gotten the ideal inverse relationship of H2O2 decomposition with the time the enzyme got to react with the substrate. Ideally, the more the substrate got to interact with the enzyme, the less KO4 would be used to indicate the presence of H2O2. This is true for our graph but only at the 360 second point. Everything else is a little off.

Conclusion

The decomposition rate of the hydrogen peroxide is directly related with the enzyme activity. This is because enzymes speed up reactions by lowering the activation energy needed for the reactants to be converted to products. Although our data does not conform to the accepted trends, we know that the longer an enzyme is allowed to act on a substrate, more substrate will be catalyzed. Since more substrate is catalyzed, it will take less indicator to find how much substrate is left.

Graphs and Data)

Our data