Diffusion And Osmosis Quiz Questions With Answers

The correct answer is "The movement of molecules from an area of higher concentration to an area of lower concentration" because diffusion is specifically trying to equalize the percentage, or concentration, of all substances in two areas. Therefore, molecules move from a higher concentration to a lower concentration to try to balance the two out.

Active transport is the movement of molecules from an area of lower concentration to an area of higher concentration. Because this defies the law of diffusion, it takes the proteins on the membrane energy to transport molecules across.

It is important that IV tubes contain the same concentration of saline as our blood (0.9%). This is necessary to keep our cells from either popping (in hypotonic solutions) or crenating (in hypertonic solutions).

Distilled water is hypotonic, and therefore has a higher concentration of water than red blood cells. Therefore, water will diffuse into the red blood cells, causing them to expand. Because the concentration of water in distilled water is 100%, water will never cease to diffuse in, because the concentration will never be equal. Thus, water will continue diffusing in until the cell pops.

As we observed in the Diffusion Through a Membrane lab, starch cannot pass through a semi-permeable membrane. We know this because of the solution surrounding the "cell" we constructed remained amber, instead of turning purple. Starch is too large a molecule to pass through the membrane of a cell.

Facilitated diffusion is the transfer of molecules from a higher concentration to lower concentration (passive transport) through the proteins on the membrane. Molecules that enter through the proteins are often too large or ionic/polar to enter straight through the phospholipid bilayer. These are also the only molecules which can undergo active transport.

Starch is too large to pass through the proteins on the membrane of a cell, and Oxygen and Ethanol pass through the phospholipid bi-layer via passive transport and cannot be stopped.

A hypotonic solution has a lower solute concentration compared to the cells it surrounds. In this case, a 1.5% saline solution has a lower salt concentration than the inside of human cells, which typically have a saline concentration of around 0.9%. When cells are placed in a hypotonic solution, water moves into the cells, causing them to swell and potentially burst.

Lipids are a diverse group of molecules that include fats, oils, phospholipids, and steroids. While some lipids are large molecules, they can still pass through the cell membrane due to their hydrophobic (water-fearing) nature. The cell membrane is composed of a phospholipid bilayer, which has a hydrophobic interior. This allows lipids to dissolve in the membrane and pass through it relatively easily. In contrast, large hydrophilic (water-loving) molecules, such as proteins and carbohydrates, cannot pass through the cell membrane without the assistance of transport proteins.

Endocytosis- General category of allowing molecules in via pockets of the cell membrane Phagocytosis- Engulfing large particles by extension of the cytoplasm, specifically solid particles Pinocytosis- Cell membrane folds in and forms a vesicle, takes in molecules like proteins Exocytosis- expelling molecules by allowing vacuole with unwanted molecule to connect to membrane and open out of the cell (reverse of Endocytosis)