(3 points) Simple diffusion moves molecules from an area of higher concentration to an area of lower concentration without an input of energy. Facilitated diffusion follows the same rules as regular diffusion (higher to lower concentration and no energy input), but uses protein carrier molecules to allow substances that are fat soluble to diffuse through the cell membrane. 5. List three examples of passive transport mechanisms. (3 points) • Movement of O2 through membrane • Movement of glucose into cells • Movement of H2O in & out of cells • Formation of kidney filtrate 6.
Active transport - a cell uses ATP to move substances from an area of lesser concentration to an area of greater concentration. Nerve cells and muscle cells have sodium pumps to return Na+ ions to the exterior of the cells; this prevents spontaneous impulses. Cells of the small intestines absorb glucose and amino acids from digested food by active transport. 5. Filtration - pressure forces water and dissolved materials through a membrane from an area of higher pressure to an area of lower pressure.
The phospholipids are arranged in two layers (a bilayer). The phosphate heads are polar molecules and so are water-soluble. The lipid tails are non-polar and therefore are not water-soluble. This means that the phospholipids are arranged with the heads in contact with the cytoplasm which is a watery environment. The tails are protected from this, by being as far from the cytoplasm as
This is because of the hydrogen bonding between water molecules and the molecules are more difficult to separate. Also, very large amounts of water cannot freeze easily or even completely. It can also be used as a solvent as it is a polar substance. There is also the solubility of the water, as it can act as a gas in the environments, which can be helpful for many organisms. It can be seen as a form of transport too, for many different cells.
4. What is the main difference between simple diffusion and facilitated diffusion? (3 points) Simple diffusion moves substances from an area of higher concentration to an area of lower concentration; it does not require energy. Facilitated diffusion moves substances from an area of higher concentration to an area of lower concentration; it does not require energy but the transported substance either binds to protein carriers in the membrane and is ferried across or moves through water-filled protein channels. 5.
o Carbon dioxide produced by respiration diffuses out of cells. Osmosis: - Water often moves across boundaries by osmosis. - Osmosis is the diffusion of water from a dilute to a more concentrated solution through a partially permeable membrane that allows the passage of water molecules. - Differences in the concentrations of the solutions inside and outside a cell cause water to move into or out of the cell by osmosis. - If there is a higher solute concentration on one side of a membrane, water will move in that direction.
The phospholipid bilayer is made up of a double layer of fatty acids that have a hydrophobic interior and a hydrophilic exterior. Within the membrane are proteins and other structures that help regulate what enters or exits through the membrane. Other functions of the cell membrane include the transport of proteins which is allowing water-soluble substances to move through their interior. Some transport proteins ATP as an energy source to actively pump substances across the membrane. Signal transduction happens when a membrane protein may have a binding site with a specific shape that fits the shape of a chemical messenger, such as hormones & other extracellular substances that trigger changes in cellular activity.
Hypotonic solution is one of two solutions that has a lower concentration of a solute. Why do the smaller sized jelly balls promote fermentation more efficiently than those that are larger? It has been found that the answer to this question depends not on the surface area of the balls, but the ratio of surface area to the volume enclosed. A large SA/Vol ratio is required so that there is sufficient area for diffusion to occur to allow molecules to enter the cell and provide adequate material for the cell. If cells were much larger than they are, it would take so long for nutrients to diffuse from the surface to the centre that the cell would not function properly.
INTRODUCTION Diffusion and osmosis are central concepts in biology,both are at the same cellular and org In order for cells to interact and function effectively used chemicals and other essential substances must be able to move across the cell membranes and across the cells. Due to this, liquid molecules are always randomly in motion and at different directions.As they move, there is a possibility to spread out from areas with fewer molecules.This process of spreading out is called diffusion. Diffusion takes place constantly around us, in our body system and therefore very necessary to our cell functioning. It allows certain substance to move in and out of cell walls from a higher concentration to a lower concentration of solute. For example oxygen diffuse from the air sacks in the lungs into the blood capillaries because the concentration of oxygen is higher in the air sacs and lower in the capillary blood.
Each molecule moves independently of others, the movement is random, and there is no use of energy in the process whatsoever. In addition to the concentration of the molecule, the rate of diffusion also depends on the size of the molecule. Diffusion can occur in liquids, semi-solids, gels, and gases, each with a different diffusion rate. At higher temperatures, the heat energy causes the molecules to collide into each other, therefore causing diffusion to occur more rapidly, whereas with colder temperatures, there are fewer collisions, and slower diffusion through a medium. Osmosis is the net diffusion of water across a semi-permeable membrane.