Diffusion is a Latin word that means to spread out. It is the movement of atoms from a region of higher concentration to a region of low concentration, which is referred as a concentration gradient. Diffusion is also a process in which molecules intermingle as a result of their kinetic energy of random motion. The tendency toward diffusion is a very strong state even at room temperature because of the high molecular velocities associated with the thermal energy of the particles. It mainly occurs in gaseous state or within gas molecules. It helps in exchange of gases during respiration, photosynthesis, and transpiration. Diffusion doesn’t need water for movement. When molecules are even throughout, it is called an equilibrium. Diffusion does not involve chemical energy. Molecules diffuse special transport proteins that are found in within the cell membrane, called facilitated diffusion, otherwise it is called only simple diffusion. Diffusion maybe a simple diffusion and a facilitated diffusion. Simple diffusion occurs unassisted while facilitated is an assisted diffusion in a way that requires a carrier molecule.In plant cells, diffusion occurs in osmosis.
Diffusion is an important process to plants because water moves into plant cells by osmosis. Osmosis is the diffusion of water across a semi permeable membrane. There are some nutrient molecules that diffuse from the atmosphere and into air spaces in leaves. Water vapor then evaporates from the surface of leaf by diffusion through the open stomata. Diffusion plays a huge role into the movement of photosynthetic products (ex. Sugars into phloem for transport throughout the plant). When a leaf is photosynthesizing the concentration of carbon dioxide outside the cell is greater than the concentration inside, so carbon dioxide diffuses into the cell. Also the concentration of oxygen inside the cell is greater than the concentration inside, so oxygen diffuses out of the cell. Since the cell membrane is composed of lipid bilayer, the lipid-soluble materials use simple diffusion to cross membrane surface. Substances with low solubility can move across membrane via facilitated diffusion. During this process, substances binds to a transporter molecule, called ionophore (transports the substance across the membrane and down its concentration gradient).
In animal cells, we need glucose and oxygen which is carried by the red blood cells. Oxygen and nutrients diffuse into body tissues. The capillaries contain a high concentration of oxygen and nutrients and the body tissues contain high concentrations of carbon dioxide and metabolic waste. The carbon dioxide and metabolic waste diffuses into the capillaries. Waste products are eventually eliminated and the nutrients exchange is a continuous cycles.
Diffusion is an important process to plants because water moves into plant cells by osmosis. Osmosis is the diffusion of water across a semi permeable membrane. There are some nutrient molecules that diffuse from the atmosphere and into air spaces in leaves. Water vapor then evaporates from the surface of leaf by diffusion through the open stomata. Diffusion plays a huge role into the movement of photosynthetic products (ex. Sugars into phloem for transport throughout the plant). When a leaf is photosynthesizing the concentration of carbon dioxide outside the cell is greater than the concentration inside, so carbon dioxide diffuses into the cell. Also the concentration of oxygen inside the cell is greater than the concentration inside, so oxygen diffuses out of the cell. Since the cell membrane is composed of lipid bilayer, the lipid-soluble materials use simple diffusion to cross membrane surface. Substances with low solubility can move across membrane via facilitated diffusion. During this process, substances binds to a transporter molecule, called ionophore (transports the substance across the membrane and down its concentration gradient).
In animal cells, we need glucose and oxygen which is carried by the red blood cells. Oxygen and nutrients diffuse into body tissues. The capillaries contain a high concentration of oxygen and nutrients and the body tissues contain high concentrations of carbon dioxide and metabolic waste. The carbon dioxide and metabolic waste diffuses into the capillaries. Waste products are eventually eliminated and the nutrients exchange is a continuous cycles.
ABOUT PICTUREThe first diagram shows particles in a liquid. The second shows the same liquid a few second later after the particles have spread out. An example for the diagram is if you add a lump of sugar into a beaker of water. A lump of sugar is composed of many individual sugar molecules and even as a solid lump, the individual sugar molecules are in motion. When it is dropped in water, it begins to dissolve. Individual sugar molecules move randomly and constantly from the area where they are common to the area where they are scarce. This type of motion when molecules move from areas of their higher concentration to the areas of their lower concentration called diffusion. Diffusion continues until all the sugar molecules become evenly dispersed throughout the beaker. The rate of diffusion is affected by the temperature, size of molecules, and the steepness of the concentration gradient.
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