Answer: Molecule: Some molecules, such as carbon dioxide and oxygen, can diffuse across the plasma membrane directly, but others need help to cross its hydrophobic core. In facilitated diffusion, molecules diffuse across the plasma membrane with assistance from membrane proteins, such as channels and carriers.
Glucose:Glucose cannot move across a cell membrane via simple diffusion because it is simple large and is directly rejected by the hydrophobic tails. Instead it passes across via facilitated diffusion which involves molecules moving through the membrane by passing through channel proteins.
Starch: Starch does not pass through the synthetic selectively permeable membrane because starch molecules are too large to fit through the pores of the dialysis tubing. ... Diffusion results from the random motion of molecules. Diffusion moves substances from regions of higher concentration to regions of lower concentration.
Protein: Can all membrane proteins diffuse freely around the membrane? Many, but not all membrane proteins can diffuse laterally through the lipid bilayer. Some proteins cannot do this because of their attachment, either to other proteins or to the underlying cytoskeletal filaments.
Iodine: The Dialysis tubing provides a semi-permeable membrane. Only allowing smaller molecules to pass through it. Iodine molecules are small enough to pass freely through the membrane, however starch molecules are complex and too large to pass through the membrane. ... Thus iodine diffused into the tube with the starch.
Water: Water also diffuses away from areas of high free water concentration into areas of more solute concentration. ... Thus, only water can diffuse. This diffusion of water across a semi-permeable membrane is called osmosis.
Salt: In turns out when salts are exposed to water, they dissolve into charge atoms (called ions). These atoms are very tiny and mobile and can easily diffuse from the surface past the meat molecules, given enough time.
Hope this helps.... Stay safe and have a great day/night!!! :D
