AP Biology Students Examine Rate of Photosynthesis

In their study of photosynthesis, the AP Biology students are carrying out the "leaf disc assay" in which they cut disks out of plant leaves and use a syringe to force the air in the leaves' sponge spongy mesophyll out replacing it with sodium bicarbonate. They then expose the leaves to light and measure the rate of "leaf floatage" as photosynthesis releases oxygen into the spongy mesophyll causing the disks to float. The students count how many disks are floating at 30 second intervals until all the disks are floating or 10 minutes has elapsed. Their baseline experiment involved comparing the rates of photosynthesis in five different type of leaves: spinach, kale, Acuba japonicum, ivy and a red Coleus.

Mallory gets ready with the "fish bowl" heat sink, while Beth uses the hole punch to produce their leaf disks

Lindsay cuts leaf disk from her sample.

Samantha is loading her syringe with the leaf disks.

Ansley is looking for "leaf floation" in her setup.

Neal cuts disks for the next run, while Thomas watches for successful floataion.

Indira pumps the leaf disks in the syringe to get the air out and sodium bicarb into the disks.

......meanwhile Lindsay is still cutting disks......

Meagan smiles while waiting for her disks to float.

Kaitlin is forcing the air out of her disks as Audrey prepares a new leaf for "disking".

Rachael removes the air from this team's disks, while Liv and Allegra cut addition disks, apparently all of this work is under the watchful eyes of their supervisor, Emily

Maddie and Hadley ca not belief how difficult is is to get the leaf disk to discharge their oxygen, uptake the sodium bicarb which is heavier and SINK!!!