Photosynthesis: "Floating Disk" Lab
Equation for Photosynthesis:
Set-up of the Experiment:
Materials:
- 100 mL of distilled water
- 1g of baking soda (source of carbon dioxide)
- Baby organic spinach
- Hole puncher
- Syringe plunger
- Beakers
- Heating lamp
- Timer
Set-Up:
1) Dissolve the baking soda in water to create a carbon dioxide mixture.
2) Punch holes in the baby organic spinach leaves.
3) Remove the plunger and place the leaves in the syringe.
4) Release the excess air by replacing the plunger in the syringe with the leaves.
5) Place the carbon dioxide mixture in the syringe.
6) Get rid of excess air by tapping the bubbles in the syringe.
7) While shaking the syringe to ensure the leaves remain in the mixture, place a finger on the tip of the syringe and pull the plunger to create a vacuum.
8) After the leaves sink to the bottom, put the mixture combined with leaves into the beaker with the carbon dioxide water.
9) Place a glass beaker with water in it (a.k.a. heat sink) on top of the beaker with the leaves.
10) Put the heat lamp directly above the beaker so that the heat sink absorbs the heat energy from the lamp but allows the light to reach the leaves.
11) Calculate the time it takes for the leaves to rise to the top to determine the rate of photosynthesis.
Independent Variable: Amount of oxygen released when exposed to the light from the heat lamp.
Dependent Variable: Rate of Photosynthesis represented by the speed of the leaves floating to the top.
Possible Variables of Change: The concentration of carbon dioxide in the water, the color of the heat lamp, and the temperature of the water.
The variable that could be tested is the temperature of the water.The 'floating disks' would be affected by the heat. If the water was warmer, the leaves would rise to the top faster which means the rate of photosynthesis would increase. If the water was colder, the leavers would take longer to produce oxygen gas, and would not rise to the top as fast as warmer water.
- 100 mL of distilled water
- 1g of baking soda (source of carbon dioxide)
- Baby organic spinach
- Hole puncher
- Syringe plunger
- Beakers
- Heating lamp
- Timer
Set-Up:
1) Dissolve the baking soda in water to create a carbon dioxide mixture.
2) Punch holes in the baby organic spinach leaves.
3) Remove the plunger and place the leaves in the syringe.
4) Release the excess air by replacing the plunger in the syringe with the leaves.
5) Place the carbon dioxide mixture in the syringe.
6) Get rid of excess air by tapping the bubbles in the syringe.
7) While shaking the syringe to ensure the leaves remain in the mixture, place a finger on the tip of the syringe and pull the plunger to create a vacuum.
8) After the leaves sink to the bottom, put the mixture combined with leaves into the beaker with the carbon dioxide water.
9) Place a glass beaker with water in it (a.k.a. heat sink) on top of the beaker with the leaves.
10) Put the heat lamp directly above the beaker so that the heat sink absorbs the heat energy from the lamp but allows the light to reach the leaves.
11) Calculate the time it takes for the leaves to rise to the top to determine the rate of photosynthesis.
Independent Variable: Amount of oxygen released when exposed to the light from the heat lamp.
Dependent Variable: Rate of Photosynthesis represented by the speed of the leaves floating to the top.
Possible Variables of Change: The concentration of carbon dioxide in the water, the color of the heat lamp, and the temperature of the water.
The variable that could be tested is the temperature of the water.The 'floating disks' would be affected by the heat. If the water was warmer, the leaves would rise to the top faster which means the rate of photosynthesis would increase. If the water was colder, the leavers would take longer to produce oxygen gas, and would not rise to the top as fast as warmer water.
Questions:
a. What is the purpose of creating a vacuum with the syringe? (relate this point to the anatomy diagram)
The vacuum within the syringe causes the xylem guard cell to remove oxygen from the leaves so water can penetrate the palisade layer of the leaf. This is necessary to sink the leaves to the bottom. If there was no vacuum, the experiment would not accurately measure the rate of photosynthesis because excess oxygen would remain in the leaf's air spaces.
b. Where did the leaf disks get the carbon dioxide needed for photosynthesis?
In the experiment, the leaves got the carbon dioxide from the baking soda dissolved in water. This carbon dioxide is needed for photosynthesis. In reality, plants get the carbon dioxide from the gases exhaled by human beings instead of baking soda.
c. What made the leaf disks float?
The heat lamp gives the thylakloid membrane of the chloroplasts energy to split the water molecules. Oxygen is release from the splitting of these molecules and help float the leaves to the top.
The vacuum within the syringe causes the xylem guard cell to remove oxygen from the leaves so water can penetrate the palisade layer of the leaf. This is necessary to sink the leaves to the bottom. If there was no vacuum, the experiment would not accurately measure the rate of photosynthesis because excess oxygen would remain in the leaf's air spaces.
b. Where did the leaf disks get the carbon dioxide needed for photosynthesis?
In the experiment, the leaves got the carbon dioxide from the baking soda dissolved in water. This carbon dioxide is needed for photosynthesis. In reality, plants get the carbon dioxide from the gases exhaled by human beings instead of baking soda.
c. What made the leaf disks float?
The heat lamp gives the thylakloid membrane of the chloroplasts energy to split the water molecules. Oxygen is release from the splitting of these molecules and help float the leaves to the top.
Respiration Lab:
Equation of Respiration:
Hypothesis: The 1a respirometer will perform faster cellular respiration than 2a or 3a because it contains germinating seeds that are actively undergoing photosynthesis and respiration instead of non-germinating seeds and beads that only have potential energy to perform respiration or no energy at all; therefore, the rate of respiration of the seeds will be measured by the amount of carbon dioxide gas in the pipet tip.
Three Respirometers:
The Set-Up:
Data Tables:
Graph of Germinating Peas:
Graph of Oxygen Consumption:
Conclusion Questions:
1. Write a conclusion statement that relates to the state of seed germination that was demonstrated by this lab exercise and your data.The data from the respirometers after the time periods suggests that the germinating seeds go through cellular respiration faster than non-germinating seeds. The experiment was successful in the performance of the procedure and data collection. The hypothesis is not rejected because the data supports it. Possible sources of error include not accurately timing the rates and not soaking the cotton in enough KOH.
2. Graphs shown above.
The rate of oxygen consumption for the germinating seeds = Initial Difference/Time
= 0.9 mL/ 5 min = 0.18
3. In this lab exercise, what is the purpose of the:
a. Beads: The beads are a control group to make sure there is no change in volume when non- living things are used.
b. KOH: The KOH allows oxygen to enter the leaf by removing carbon dioxide.
c. Respirometer: The respirometer is used to measure the rate of respiration of the seeds.
2. Graphs shown above.
The rate of oxygen consumption for the germinating seeds = Initial Difference/Time
= 0.9 mL/ 5 min = 0.18
3. In this lab exercise, what is the purpose of the:
a. Beads: The beads are a control group to make sure there is no change in volume when non- living things are used.
b. KOH: The KOH allows oxygen to enter the leaf by removing carbon dioxide.
c. Respirometer: The respirometer is used to measure the rate of respiration of the seeds.