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bio204.s1.d38

cava bio 204 s1.d38 3.07 Movement across Membranes

QuestionAnswer
Movement across a cell membrane that does not require additional energy from the cell is called [...] transport Movement across a cell membrane that does not require additional energy from the cell is called passive transport
The cell membrane is selectively permeable, or semipermeable, meaning that it [...] to cross. The cell membrane is selectively permeable, or semipermeable, meaning that it only permits certain substances to cross.
Molecules in a liquid or gas are in constant random [...]... therefore, they scatter randomly throughout whatever container or liquid you put them in... we call this 'diffusion'. Molecules in a liquid or gas are in constant random motion... therefore, they scatter randomly throughout whatever container or liquid you put them in... we call this 'diffusion'.
When molecules move about randomly, it *looks* like they move from an area of high concentration to low concentration. In reality, they aren't moving anywhere in particular; their random movements naturally cause them to [...]. When molecules move about randomly, it *looks* like they move from an area of high concentration to low concentration. In reality, they aren't moving anywhere in particular; their random movements naturally cause them to spread out evenly.
Diffuse means '[...]', which is what happens when you allow molecules to move about randomly, the end up evenly spread out... we call the process of becoming diffuse, diffusion. Diffuse means 'evenly spread out', which is what happens when you allow molecules to move about randomly, the end up evenly spread out... we call the process of becoming diffuse, diffusion.
Unfortunately, textbooks often define diffusion as 'particles moving from an area of high concentration to an area of low concentration'... as if the particles have [...]. They don't. Unfortunately, textbooks often define diffusion as 'particles moving from an area of high concentration to an area of low concentration'... as if the particles have some idea of what they're doing. They don't.
Concentration [...] = when you can see a smooth transition from high to low concentration.... like when you've dropped food coloring in water and it hasn't completely mixed yet. Concentration gradient = when you can see a smooth transition from high to low concentration.... like when you've dropped food coloring in water and it hasn't completely mixed yet.
K12 says: "During diffusion, molecules will move from an area of higher concentration to an area of lower concentration." This is only partially true. In actuality, during diffusion, molecules move randomly in [...] directions. K12 says: "During diffusion, molecules will move from an area of higher concentration to an area of lower concentration." This is only partially true. In actuality, during diffusion, molecules move randomly in all directions.
[...] transport is movement cell membrane, a process that requires energy. Most often this energy comes from ATP. Active transport is movement cell membrane, a process that requires energy. Most often this energy comes from ATP.
Whether active transport moves molecules to areas of higher concentration (aka up a concentration gradient) or to areas of lower concentration (aka down a concentration) is irrelevant! What defines active transport is that it requires [...]. Whether active transport moves molecules to areas of higher concentration (aka up a concentration gradient) or to areas of lower concentration (aka down a concentration) is irrelevant! What defines active transport is that it requires energy.
Endocytosis = (endo=inner) + (cyto=cell) = brining something [...] the cell. Endocytosis = (endo=inner) + (cyto=cell) = brining something into the cell.
Exocytosis = (exo=out) + (cyto=cell) = pushing something [...] the cell. Exocytosis = (exo=out) + (cyto=cell) = pushing something out of the cell.
Created by: mr.shapard