Background Information

Sunflower seeds were first from the Americas. These seeds pack and contain many essential nutrients and are considered “storehouses”. Some examples of these nutrients that are vital to the human body include zinc and iron. In today’s society, the most common form of sunflower seeds are in the form of sunflower oil. However, why does this all matter? Why do we care if these sunflower seeds can undergo cellular respiration and sustain life? We know that all seeds are cells and so they go through cellular respiration in order to maintain homeostasis and life. Also, sunflower seeds are dormant which means that they do not migrate or move, but are fixed in one position. With being dormant, these seeds provide a unique adaptation to their environment able to germinate and grow in a fixed position. These periods of dormancy allow for the seed to wait for the optimal environmental conditions in order to fully grow. When germination occurs, the respiration rates increase tenfold so that they can account for and make up for the necessary materials.

Results

Analysis

From these data tables, my group is able to draw many different patterns and analyses. When we look at the graphs for the Sunflower seeds at room temperature, the germinating seeds seemed to have a higher rate of Oxygen Consumption/Respiration rate that that of the dry seeds + the glass beads. When looking at the graphs for the respirometers for the seeds at 10*C, there was a greater rate of oxygen consumption/respiration with the germinating seeds rather than the dry seeds + glass beads. When our group looked at the spreadsheet with the other corrected changes in volume for the sunflower seeds, there seemed to be a rather similar data set for the respirometers at room temperature with the germinating seeds. Then when we look at the dry seeds with the glass beads, all the groups data sets were slowly decreasing in their corrected change in volume. However, when we look at the data for the respirometers at 10*C, the germinating seeds seems to have a conclusive trend of increasing and that occurs in all groups. However, when we reach to the dry seeds with the glass beads at 10*C, there seems to be confusion between groups. Our groups corrected change in volume increased from .02 to .08. On the other hand, Group 1’s change in volume fluctuated as it went from -.04 to .05 back to .01. With group 3, there corrected change in volume constantly decreased while the other groups decreased. This may have occurred due to the fact that some of the food coloring may have leaked and not been put in properly, or some groups may have read their numbers wrong. Also, this may have occurred because a group may have forgotten to keep their ice bath constantly at 10*C and the temperature constantly fluctuated.

Procedure

1. Obtain all materials; the respirometers will be already available and assembled.2. In all respirometers, place an absorbent cotton ball at the bottom, drop three drops of potassium

hydroxide solution, and then put a wad of nonabsorbent cotton on top of the absorbent cotton with KOH. Do this for all 6 respirometers.

3. To assemble the first kind of respirometer, first find the volume of 20 sunflower seeds that are germinating using the water displacement technique with a graduated cylinder. Record this volume as it will be used in assembling the other respirometers. Put the 20 sunflower seeds into the respirometer. Repeat this with another respirometer.

4. To assemble the second kind of respirometer, take 20 non-germinating (dry) sunflower seeds and use the same water displacement technique to find the volume. Next, add glass beads to make the volume of the dry seeds and the beads to equal the volume of the germinating seeds in step 3. Put both seeds and beads into the respirometer. Repeat this twice with two respirometers.

5. To assemble the third kind of respirometer, use the water displacement technique to determine how many glass beads are needed to match the volume of the germinating seeds from step 3. Then, put the glass beads into the respirometer.

6. Place the rubber stopper with a calibrated pipet on top of each respirometer, making sure each fits snugly and without any leaks.

7. Place one of each type of respirometer into the room temperature water bath, and do the same for the 10°C water bath, so that the pipets rest across the tape around the tub and that the end of the respirometer containing the seeds and beads are immersed in water. Start your timer now.

8. Once the timer hits 7 minutes, put a drop of colored dye on the tip of each pipet, and immerse all respirometers completely into the water.

9. In regular 3 minute intervals starting from 7:00 (0 minutes on the lab data sheet), record the required data into the data table except for the corrected ΔV. Continue to record data until the 22 minute mark on your stopwatch (draw in an additional line for data on your lab sheet).

10. Calculate corrected ΔV = ΔV (for respirometer 1 or 2) – ΔV of respirometer 3.

Experimental Design

Our control group for this experiment is respirometer 3, which only contains the glass beads and no sunflower seeds that undergo cellular respiration. This respirometer is also used to calculate the corrected ΔV since no oxygen is actually consumed and the movement of water up the pipette is not influenced in any way.

1. Materials: Room temperature water bath, cold water bath, container of ice, paper, water, germinating sunflower seeds, non-germinating sunflower seeds, glass beads, respirometers, graduated tube, absorbent cotton balls, nonabsorbent cotton, 15% potassium hydroxide solution, dropping pipets, forceps, thermometers, stopwatch, calculators.

2. Description and Designa. The data that will be collected in this experiment are the volume of the pipet, the ΔV, and the

corrected ΔV for all six respirometers.b. Only one trial will be completed for all six respirometers.c. The temperature will be controlled by either adding ice cubes to maintain a constant 10°C and by

keeping room temperature constant. Additionally, the number of molecules of gas will be the same since the volumes of cotton, seeds, and beads will be around the same in each respirometer.

d. The data will be interpreted by using the corrected ΔV as a measurement of how quick the rate of cellular respiration is. A greater ΔV will show that more cellular respiration takes place while a lower ΔV shows that less respiration takes place.

e. Four graphs will be made, using the room temperature respirometers containing germinating seeds and dry seeds + beads as well as the 10°C respirometers containing germinating seeds and dry seeds + beads.

3. The pipets are very sharp, so gloves will be worn. Lab coats and safety goggles/glasses will also be worn to protect from the potassium hydroxide.

Conclusion

Based on our group’s data, we reject our first hypothesis that more cellular respiration would occur at lower temperatures, but accept our second hypothesis that germinating seeds will undergo more cellular respiration than non-germinating seeds. Our data shows a very strong correlation between colder temperatures and less respiration; for example, the corrected ΔV of germinating seeds at 10°C is only 0.17 while the corrected ΔV of germinating seeds at room temperature is 0.25. This data disproves our hypothesis that more cellular respiration would take place at lower temperatures. However, when we look at the percent changes of our data, we have a different conclusion/result. For the corrected ΔV for the germinating seeds at 10*C, the percent change is 325%. It increased from .04 to .17 and to calculate that, we did .17-.04/.04. Likewise, when we look at the correct ΔV for the germinating seeds at room temperature, the percent change is 316.67%. It increased from .06 to .25 and to calculate that, we did .25-.06/.06. Based on the percent changes however, we do support our hypothesis. Then, when we look at the class averages for sunflower seeds, the corrected ΔV for the germinating seeds at 10*C ended up at .13 while the corrected ΔV for the germinating seeds at room temperature was .24. With this, we would say that this data would reject our hypothesis. However, when we take a closer look at the percent changes for the class averages, for the germinating seeds at room temperature, it is 380% while the germinating seeds at 10*C have a percent change of 550% which then supports our hypothesis. Our data does support our second hypothesis that germinating seeds have more respiratory actions than non-germinating seeds. In our data can be seen a dramatic difference between germinating and dry seeds, with the ΔV of germinating seeds maxing out at 0.25 while the ΔV of non-germinating seeds maxes out at only 0.08. Errors might have taken place while we carried out the experiment. For one, the volumes for some respirometers might be off due to us not using the meniscus to measure the volume. Another source of error would be the difference in amount of dye placed on each pipet. Some pipets had large amounts of dye while others had little. Furthermore, we did not keep a constant eye on the ice bath, and the temperature rose to 11 degrees in one instance. To further our research, we could do multiple trials and compare our results with groups who did different seeds, such as corn or peas. The significance of this research to sunflower seeds is influential; through this experimentation we gather key facts about sunflower seeds: that they undergo cellular respiration even when they are not germinating, and that their activity is limited by the temperature around them.