Place both trays in an outside location. Shelter them from rain but expose them to the sun. As the seedlings grow taller, insert the ice-cream sticks in the corners of the wrapped tray to keep the plastic from the touching the plants, them replace the plastic wrap. Weekly, observe and record the temperatures of both trays. You will notice that the closed environment is warmer than the other tray.
Plants have tiny openings called the stomata on the underside of their leaves.
The function of the stomata is to let out excessive gases, such as oxygen, and to take in carbon dioxide. If the stomata are blocked, the leaf is unable to take in carbon dioxide and dies. Keep the plant in the dark for several days. Then select two leaves and coat their upper surfaces heavily with petroleum jelly. Select two more leaves and heavily coat their under surface with petroleum jelly.