Research Question |
How does the size of a leaf chad affect the rate of photosynthesis? |
Predictions |
If a larger leaf chad is submerged in water then it will take photosynthesis longer to float the chad to the top of the water because there is more material/mass to raise. |
Experimental Design |
Step 1. Using a measuring tube measure 100 ml of water into a beaker
2. Mix the 100 ml of water with 1 g of baking soda using a spoon
3. Use a 4mm cork borer to cut out 12 leaf chad circles from baby spinach leaves
4. Place the chads inside of a syringe
5. Fill the syringe partially with the baking soda water and compress until all of the air inside of the syringe is expelled.
6. Place a finger on the end of the syringe to create a vacuum seal and pull the plunger down slightly while shaking for 5-10 seconds.
7. Maintaining pressure immediately compress the plunger until all of the chads sink.
8. Place the chads and water back into the beaker, making sure they sink to the bottom. Remove any that do not sink 1 or 2 (Only 10 are needed which is why 12 chads are needed to ensure that enough chads are present if 1 or 2 do not sink).
9. Place the cup under a light source for ten minutes recording how many chads float to the top every minute, stirring gently with spoon every minute and thirty seconds.
10. Repeat process twice more for the 4mm chads and 3 times for each of the other sizes (6mm, 10mm, 17mm) |
Conclusion |
Contrary to the previous hypothesis, the 17 millimeter leaf chad had the best rate of photosynthesis within the first three minutes. Over all of the trials none of the other leaf sizes could produce as many chads within the begining minutes like the 17mm chads could. At three minutes four 17mm leaf chads had floated up, while only two had risen for the 6mm and the 10mm. However in the later stages of the trials each size showed similar data and reached 10 chads by about seven minutes. It is possible that this data is the result of buoyancy rather than photosynthesis. Larger leaves are typically more bouyant, so this could explain why the 17mm chads rose so quickly within the first three minutes, or there could have been some leftover baking soda in the cup from previous experiments adding extra CO2, or some of the chads were not sunk properly. |
Investigation Theme |
POS |
Grade Level |
High School Students (Grades 9,10,11,12) |
School Name |
West High School |
Session |
Spring 2019 |