Carbon dioxide and oxygen cannot pass through but move in and out
Solution
Cut open an onion.
Use forceps to peel a thin layer of epidermis from the inside.
Lay the layer of epidermis on a microscope slide.
Add a drop of iodine solution to the layer.
Carefully place a coverslip over the layer.
Observe it under a microscope to see onion cells.
Thermal energy to Gravitational PE to Kinetic energy.
