Got Leaves? Is there a difference in the photosynthetic rate between baby leaves and older leaves? By Emily, Katherine, Jane and Kristin ogy/photysyn.mp3

Problem Is there a difference in the photosynthetic rate between baby plants and older plants? Why? – When we found out that we had to do a project surrounding photosynthesis, we thought it would be interesting to test the difference between younger leaves and older leaves.

Hypothesis Older leaves would have a faster photosynthetic rate because of the many chloroplasts.

Photosynthesis Photosynthesis is the process by which plants use the sun’s energy to produce food. It takes place in the chloroplast within the leaf. The chlorophyll absorbs the sun’s energy, which then produces carbon dioxide, water, sugar, and oxygen.

Variables Control: Location, temperature, water, soil, sunlight, same species of plant Independent: Age of the leaves Dependent: Rate of Photosynthesis

Materials 4 Pea plant seeds 4 Sunflower Seeds 2 Petri dishes Paper Towels 8 Pots 250 ML of Soil into each pot Sun light 50 ML of Water into each pot

Process 1. Select two types of seeds 2. Seed Germination: a. Soak the seeds over night (about 24 hours needed) b. Wrap seeds with paper towels c. Keep them moist in a warm temperature d. Put seeds into soil after 7-10 days 3. Transfer the seedling into the pot

Process(cont.) 4. Set two of the same species aside for the control variable and two of the other species for the control variable. 5. The other two of the species will be used for the independent variable and the two from the other species will be used for the independent variable as well. 6. Phenol Red Process

Research Younger leaves tend to have a faster photosynthetic rate than older leaves because of higher levels of starch and large amounts of plummeting sugars. – In older leaves, stomatal response to ABA (abscisic acid ) is a lot weaker than in younger leaves. This forces the older leaves to be a protection to younger leaves. The younger leaves then become more metabolically active, causing a faster rate of photosynthesis. –

Data/Findings Our leaves were not old enough to have a difference in the rate of photosynthesis. The old leaves and the baby leaves in both plants maintained the same rate of photosynthesis based on the color and the time it took to photosynthesize.

Sunflower Photosyntetic Rate for SunflowerMinutes Control Adult 12 Control Baby 12 Independent Adult 12 Independent Baby 12

Pea Plant Photosynthetic Rate for Pea PlantMinutes Control Adult 12 Control Baby 12 Independent Adult 12 Independent Baby 12

Conclusion After research about other projects similar to ours, we found that as the leaf gets older, the photosynthetic rate would decline. Photosynthesis is like the metabolism of humans. As they get older, their photosynthetic rate slows down. This has to do with the stomata conductance of the plant. Older plants have a smaller response to ABA. This causes them to act more as protectors to the faster, younger, more active leaves.

THANK YOU!! And Special Thanks To….. Our Mentor, Brian Dorsey