Germination and Cell Respiration Lab

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.