AP生物 LABWRITE UP

1、AP BIOLOGYCell Respiration Lab Write-upOBJECTIVES· To understand respiration, dormancy, and germination.· Know how a respirometer works in terms of the gas laws; the general processes of metabolism in living organisms; · How the rate of cellular respiration relates to the amount of ac

2、tivity in a cell.· Calculate the rate of cell respiration from experimental data· Relate gas production to respiration rate· Test the rate of cellular respiration in germinating versus nongerminated seeds in a controlled experiment; and· Test the effect of temperature on the rate

3、 of cell respiration in germinating versus nongerminated seeds in a controlled experiment.PROCEDURE· Set up two water baths, one at room temperature, the other one at 10 degree Celsius· For respirometer1, Count out 50 germinating peas and place them into the graduated cylinder. · For

4、respirometer 2, put in 50 dry peas and 110 plastic beads.· For respirometer 3, only put in 150 plastic beads. (now the volumes of the respirometers should be the same) And the first set of respirometer is ready.· Prepare another set of germinating peas, dried peas plus beads, and plastic b

5、eads.· To assemble the six respirometers, obtain six vials, each with an attached stopper and pipette. Place a small piece of cotton in the bottom of each vial and, using a dropper, moisten the cotton with 15% KOH. Make sure that the respirometer vials are dry on the inside. Do not get KOH on t

6、he sides of the respirometer. Place a small wad of nonabsorbent cotton on top of the KOH-soaked absorbent cotton.· Place the first set of germinating peas, dry peas plus beads, and beads in vials1, 2, and 3. · Place the second set in vials 4,5, and 6, respectively. Insert the stopper fitte

7、d with the calibrated pipette. Place a weighted collar on each end of the vial.· Make a sling of masking tape attached to each side of each of the water baths to hold the pipettes out of the water during an equilibrium period of seven minutes. Vials 1, 2, and 3 should rest in the room temperatu

8、re bath and the other vials should rest in the 10 degree Celsius water bath. · After the equilibrium period of seven minutes, immerse all six respirometer entirely in their baths. · Allow the respirometers to equilibrate for three more minutes and then record, to the nearest 0.01mL, the in

9、itial position of water in each pipette. Check the temperature in both baths and record it in the data table. Every 5 minutes for 20minutes, take readings of the waters position in each pipette and record the data.DATATemp(C)Time(min)Beads AloneGerminating PeasDry peas and BeadsReading time XDiff.Re

10、ading time XDiff.CorrectedDiff.Reading time XDiff.CorrectedDiff.10°C05.3-5.3-5.3-55.30.05.30.00.05.30.00.0105.30.015RoomTemp05.6-5.4-5.7-55.60.05.70.00.0105.60.0155.60.05.6-0.10.1From the data we collected and the graph above, we want to find out t

11、he correlation between the rate of the respiration and the temperature, as well as the difference in respiration rate between germinating peas and dry peas. This activity uses a number of controls, by using the ideal gas law, PV=nRT, we kept the air pressure and the volume of materials in each respi

12、rometer constant. That way, we can figure out the effect of temperature on the respiration. Water moved into the respirometers pipettes because pressure decreased when the amount of oxygen was decreased (or consumed). By measuring the amount of water in the pipette, we can know the amount of oxygen

13、consumed by the peas. The vial had to be completely sealed so that gases couldnt escape and water couldnt leak into the respirometer.The graph showed that as the time goes on, the amount of oxygen consumed increases. Dry peas started consuming oxygen slower than germinating peas. And germinating pea

14、s generally consumed more oxygen than dry peas. It also tells us that the amount of oxygen consumed is greater in warmer waters, for both germinating and dry peas. ConditionShow Calculations HereRate (mL O2 /minute)Germinating Peas/10°C(0.3-0.0)/100.03mL/minGerminating peas/Room temperature（5.4

15、-5.7)/150.047mL/minDry Peas / 10°C(0.2-0.0)/100.02mL/minDry Peas/Room Temperature（5.7-(5.5+5.6)/2)/150.01mL/minThis table showed that the germinating peas in room temperature have a highest respiration rate overall, which means germination can increase the pea seeds respiration effectively. And

16、 the dry peas didnt turn out the way we expected, which we thought the rate was supposed to be higher at a warmer temperature. Instead, they have a higher rate at 10°C.It is necessary to correct the readings from the peas with the readings from the beads, because the beads served as a control g

17、roup. Its important to find the change in rate of respiration by comparing with the beads. The purpose of KOH is this experiment is to remove the C02, so that the pressure of CO2 wont affect the reading. This graph here shows the prediction of the rate of oxygen consumption as temperature increases.

18、 The consumption would drop dramatically because when the temperature gets too high, the enzyme will be denatured and end the respiration process. ConclusionIn this experiment, we hoped to see a warmer temperature can increase the rate of respiration (oxygen consumption), and germinating peas have a greater rate of respiration and consume more oxygen than dry peas. The actual experimental result was fairly close to our expectation. The data