Cellular Respiration Lab Report
Abstract:
The purpose of this lab was to measure the temperature change germinating and non-germinating respire through the means of a respirometer. This was done by using a syringe to create a respirometer for the plane seeds, and a beaker filled with heated water, then inside the syringe was Manometer fluid and Potassium Hydroxide which were used for measuring the changes and to draw away oxygen from the plant seeds. Our results from this lab were incorrect and vareid greatly from other groups because the seal on the respirometers was placed poorly, causing the experiment to not take place the way most would've collected.
Introduction:
In this lab, our focus was on Cellular Respiration of Germinating and Non-Germinating plant seeds. Cellular Respiration is the process of oxidizing food molecules, like glucose, to carbon dioxide and water.
Methods:
Materials-
Monomer fluid red, 2 drops
seeds, control, mung bean, 10
seeds, germinating, mung beans, 10
potassium hydroxide solution, KOH, 15%, 1 m:
water, tap, room temperature, 1L
capillary tubes, 2
cotton ball
cup, clear, 16 oz
fiberfill, nonabsorbent
forceps or bent paperclip
hex nuts, 4
hot glue gun
marker, permanent
paper towels
pipette, graduated
ruler, metric
stirring rod, glass
syringers, 5 mL, 2
thermometer, digital
Procedure for Respirometer Construction-
1. Push the plunger all the way into the syringe
2. Hot glue a hex nut at the end of the plunger to add weight
3. Insert a capillary tube into the end of the syringe so that about half is on the outside and the other hald is pushed all the way in on the inside
4. Add some hot glue to the capillary tube to ensure its' steadiness
5. Gently pull back the plunger after the glue cools to make sure the capillary tube moves alone with it and isn't stuck
6. Repeat steps 1-6 for the second respirometer
Procedure for Baseline Activity-
1. Fill a cup up with 16 oz of room temperature tap water
2. Place thermometer in water
3. Draw a small amount of red monomer into the capillary tube and pull it down the length of the tube. Then squirt it all back out so that a soapy coat remains. This will make the substances not stick in the tube.
4. Place 1/2 of a cotton ball in each respirometer
5. Use the glass stirring rod to push the cotton ball next to the capillary tube
6. Use a graduated pippette to insert 0.5 mL 15% potassium hydroxide in the cotton ball
7. Place some non-absorbent fiberfill in each respirometer
8. Use the glass stirring rod to push the fiberfill next to the cotton ball. This will ensure that no specimen will be consumed by the alkaline solution.
9. Repeat steps 3-8 for the second respirometer
10. Place 10 germinated mung beans into one respirometer and 10 controlled mung beans into the other
11. Put the capillary tube facing down toward the sink and replace the plunger until its at 4 mL
12. Put both respirometers in the cup of water with the capillary tubes facing out
13. Wait 3-5 minutes
14. Use a pipette to add red monomer fluid in each tip of the capillary tube
15. If the fluid is being ejected this means that there is a leak in the respirometer, re-glue if necessary
16. Use a permanent marker to mark the progression of the red monomer for 10 minutes. Also record the temperature.
17. Remove the respirometers from the water and dry them
18. Use a ruler to measure the distance between each mark
19. Calculate the volume by adding or subtracting the difference between the germinated tube and controlled tube
20. Construct a graph to show the rate of respiration
Results:
Our final results were flawed because our germinated seeds in the capillary tube had an error. The seal wasn't properly hot glued, resulting in the photosynthesis being stronger than the respiration. This made the red monomer being pushed out instead of pulled in. Our controlled test tube did what it was supposed to and the red monomer sat still.
Discussion:
In the lab, CO2 made during cellular respiration was removed by the potassium hydroxide (KOH) and created potassium carbonate (K2CO3). It was necessary that the carbon dioxide be removed so that the change in the volume of gas in the respirometer was directly proportional to the amount of oxygen that was consumed. In the experiment, water was moved toward the region of lower pressure. During respiration, oxygen will be consumed and it's volume will be reduced to a solid. The result was a decrease in gas volume within the tube, and a related decrease in pressure in the tube. If we would've set up the respirometer with the glass beads, it would've served as a control, allowing changes in volume due to changes in atmospheric pressure and/or temperature.
Conclusion:
The lab and the results gained from this lab demonstrated many important things relating to cellular respiration. It showed that the rates of cellular respiration are greater in germinating mung beans than in non-germinating mung beans. It also showed that temperature and respiration rates are directly proportional; as temperature increases, respiration rates increase as well. Because of this fact, the mung beans contained by the respirometers placed in the water at 10C carried on cellular respiration at a lower rate than the mung beans in respirometers placed in room temperature water. The non-germinating mung beans consumed far less oxygen than the germinating mung beans. This is because although germinating and non-germinating mung beans are both alive, germinating mung beans require larger amounts of oxygen to be consumed so that the seed will continue to grow and survive