AP BIOLOGY

Detailed explanation-1: -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. In contrast, glucose, iodine, and water molecules are small enough to pass through the membrane.

Detailed explanation-2: -Small uncharged molecules can diffuse freely through a phospholipid bilayer. However, the bilayer is impermeable to larger polar molecules (such as glucose and amino acids) and to ions.

Detailed explanation-3: -Plant cells and diffusion The cell membrane is said to be partially permeable because only small molecules can pass through and larger molecules such as starch or proteins cannot. Diffusion is the movement of particles from a region of higher concentration to one of lower concentration.

Detailed explanation-4: -Molecules that are too big are unable to pass through the pores. Molecules that are small enough can pass freely in and out of the membrane. Starch is a large molecule and is unable to pass through the pores in the membranes of the small intestine.

Detailed explanation-5: -In a cell membrane, this is called selective permeability. In other words, the iodine can go through the baggie, but the starch cannot. The purpose of this experiment is to show that a cell membrane is a type of barrier, and is permeable to some substances, but may not be permeable to all substances.