PHOTOSYNTHESIS LAB :)
BACKGROUND: All life on earth is powered directly or indirectly by photosynthesis. Photosynthesis is the conversion of light energy into chemical energy which is stored in the bonds of sugar. The equation for this process is:
6CO2 + 6H2O ---->C6H12O6 + 6O2
As the equation demonstrates an essential requirement for photosynthesis is CO2. CO2 enters the plant, while water and oxygen exit, through a leaf’s stomata. Since CO2 is essential to a plant’s ability to carry out photosynthesis, it will be the variable tested.
Using the floating disk technique in our experiment to measure the rate of photosynthesis, spinach leaves will be submerged in a concentration of CO2 and a concentration of water.
In this experiment, the leaves will only rise to the surface when enough CO2 and light is present to allow the leaf disks to carry out photosynthesis and produce O2.
Purpose:
Measure the rate of photosynthesis of spinach leves in the presence/absence of CO^2
6CO2 + 6H2O ---->C6H12O6 + 6O2
As the equation demonstrates an essential requirement for photosynthesis is CO2. CO2 enters the plant, while water and oxygen exit, through a leaf’s stomata. Since CO2 is essential to a plant’s ability to carry out photosynthesis, it will be the variable tested.
Using the floating disk technique in our experiment to measure the rate of photosynthesis, spinach leaves will be submerged in a concentration of CO2 and a concentration of water.
In this experiment, the leaves will only rise to the surface when enough CO2 and light is present to allow the leaf disks to carry out photosynthesis and produce O2.
Purpose:
Measure the rate of photosynthesis of spinach leves in the presence/absence of CO^2
Materials:
*sodium
bicarbonate
*liquid soap (to break surface tension of water, so
leaf discs can float)
*leaf material
*plastic
syringe (10cc or larger) ***remove any needles***
*hole punch
*plastic cups
*timer
*light source
Hypothesis= If you add 10 uniform sized spinach leaf disks into a solution with bicarbonate concentration and just water, then the disks in the concentration of sodium bicarbonate will float up faster because there is no CO2 naturally in water, so they'll have a higher rate of photosynthesis.
Independent variable: bicarbonate concentration
Dependent variable: number of disks floating after a minute
VARIABLE= presence/absence of CO^2
Control: amount of solution, size of leaf disks, amount of time cup is under light bulb, number of drops of liquid soap/ type of liquid soap
*sodium
bicarbonate
*liquid soap (to break surface tension of water, so
leaf discs can float)
*leaf material
*plastic
syringe (10cc or larger) ***remove any needles***
*hole punch
*plastic cups
*timer
*light source
Hypothesis= If you add 10 uniform sized spinach leaf disks into a solution with bicarbonate concentration and just water, then the disks in the concentration of sodium bicarbonate will float up faster because there is no CO2 naturally in water, so they'll have a higher rate of photosynthesis.
Independent variable: bicarbonate concentration
Dependent variable: number of disks floating after a minute
VARIABLE= presence/absence of CO^2
Control: amount of solution, size of leaf disks, amount of time cup is under light bulb, number of drops of liquid soap/ type of liquid soap
Procedure:
1. Prepare 300 mL of bicarbonate solution for each trial. Fill Beaker 1 only with water (no bicarbonate solution because this is the control). Fill Beaker 2 with .2% bicarbonate solution.
2. Add 1 drop of dilute liquid soap to each solution (avoid suds). The soap wets the hydrophobic surface o the leaf, allowing the solution to be drawn.
3. Punch out 10 uniform leaf disks for each beaker.
4. Remove plungers from 4 syringes; place 10 leaf disks in each syringe.
5. Push in plunger to make a vacuum and suck all the air out of the leafs.
6. Hold finger over the syringe opening and draw back the plunger; swirl disks while holding the vacuum for 10 seconds. Then release the vacuum, letting the plunger spring back. Keep doing this until the leaf disks sink and remain in the bottom of the barrel to assure there is no more air.
1. Prepare 300 mL of bicarbonate solution for each trial. Fill Beaker 1 only with water (no bicarbonate solution because this is the control). Fill Beaker 2 with .2% bicarbonate solution.
2. Add 1 drop of dilute liquid soap to each solution (avoid suds). The soap wets the hydrophobic surface o the leaf, allowing the solution to be drawn.
3. Punch out 10 uniform leaf disks for each beaker.
4. Remove plungers from 4 syringes; place 10 leaf disks in each syringe.
5. Push in plunger to make a vacuum and suck all the air out of the leafs.
6. Hold finger over the syringe opening and draw back the plunger; swirl disks while holding the vacuum for 10 seconds. Then release the vacuum, letting the plunger spring back. Keep doing this until the leaf disks sink and remain in the bottom of the barrel to assure there is no more air.
7. Pour disks and the solution from inside the syringe into appropriate CO2 concentration beakers.
10. Place beakers under light source; start timer.
11. At the end of each minute, record the number of floating disks.
12. When all of the disks are floating, end timer.
12. When all of the disks are floating, end timer.
Results:
1-6 minutes = no leaf discs have risen
7 minutes= 1 leaf disc
8 minutes = 1 leaf disc
9 minutes= 1 leaf disc
10 minutes= 1 leaf disc
11 minutes= 4 leaf discs
12 minutes= 7 leaf discs
13 minutes= 8 leaf discs
14 minutes= 10 leaf discs
Theoretical data with different concentrations of sodium bicarbonate solution.
Conclusion:
My hypothesis was supported by my data :)
My hypothesis was supported by my data :)