| A | B |
|---|
| how do particles move into or out of a cell? | by passing through the cell's plasma membrane |
| name the three types of passive transport. | osmosis, diffusion, and facilitated diffusion |
| define passive transport. | the movement of a substance through a cell's membrane without the use of energy |
| describe diffusion | diffusion is a form of passive transport where particles move to an area of lower concentration |
| eventually, dissolved particles diffuse within a liquid until they fill the volume uniformily, or reach___________ | equilibrium |
| what are solutes? | substances that dissolve in another substance |
| name the solutes found in cells. | sugars, amino acids, and ions |
| what is a solvent? | the more plentiful substance that dissolves the solute |
| what is a solution? | a mixture of solutes and solvent |
| what happens when a polar solute is added to one side of a membrane and cannot cross it? | the solute will form hydrogen bonds with the water molecules surrounding them. the water molecules that are bound to the solutes cannot cross the membrane and create unequal numbers of water molecules on the sides of the membrane. in response to this loss of equalness, water from the other side of the membrane diffuses to the side with the solute. |
| define osmosis. | the diffusion of water through a membrane in response to the addition of a solute and/or in the direction of a higher solute concentration. |
| what happens if the water molecules that move because of osmosis collect on the inside of a cell? | they will exert a pressure that can become great enough to burst the cell. |
| what is the increase water pressure that results from osmosis? | osmotic pressure |
| what kind of cells cna withstand high internal osmotic pressures? | plant and fungi cells |
| why are some cell able to withstand high internal osmotic pressure? | they have strong cell walls |
| what is a cell immersed in pure water said to be and why? | hypertonic because the cell has a greater concentration of solutes than the water around it |
| what is the pure water around a cell said to be and why? | hypotonic because it has a lesser concentration of solutes then the cell |
| what are most body cells and the tissue fluid around them said to be? why? | isotonic because the concentration of solutes in the cell and the fluid is the same. |
| if the solute concentration in the environment is lower that that in the cell, what will happen to the cell and why? | the cell will burst because water will be moving out of it. |
| what happens to a cell if it is in a isotonic solution? | the amount of water will be the same, so the cell will remain unchanged. |
| what will happen to a cell if the solute concentration in the environment it is in is higher than that in the cell and why does this happen? | the water will move out of the cell and it will shrivel. |
| what kind of permeabilty does the plasma membrane of a cell have? | a selectively permeable membrane |
| what classifies a selectively permeable membrane? | selectively permeable membranes only allow certain solutes to pass through it. |
| what are pores and what do they do? | pores are selective protein channels that transport molecules or ions through a membrane in either direction. |
| are all solutes able to pass through all pores? | no, different solute particles fit into different pores. |
| what does the ability of the cell to fit through a pore depend on? | its size, polarity, and shape |
| what is facilitated diffusion? | the diffusion of solutes through selective pores. |
| name one solute that travels using facilitated diffusion. | glucose |
| what makes facilitated diffusion different from the other two kinds of passive transport? | facilitated diffusion uses protein channels. |
| what enables cells to maintain a high level of amino acids and sugars even if the external amounts are lower? | the use of active transportation |
| what are the three types of active transport? | proton pumps, sodium-potassium pumps, and coupled channels. |
| what do proton pumps do and where are they located? | they transport protons through the membranes of mitochondria and choroplasts. |
| what is a proton? | a hydrogen atom that is missing its eletron |
| what do proton pumps make? | atp |
| what do proton pumps use to make atp? | adp |
| what is atp? | the cell's key energy-storing molecule. |
| what is the active transport of protons to make atp called? | chemiosmosis |
| what do sodium-potassium pumps do? | they use energy (atp) to power the active transport of sodium ions out through a cell's membrane. |
| what is the most important energy using process in the body? | the sodium-potassium pump |
| how much energy from a non-dividing cell used in sodium-potassium pumps? | one-third |
| why do cells use so much energy pumping sodium and potassium ions? | nerve cells use the differences in sodium and potassium ion concentrations produced by sodium-potassium pumps to send signals throughout the body. they also transport needed food particles into the cell |
| what are the two kinds of channels used to transport food into a cell? | sodium-potassium and coupled channels. |
| what happens when a molecule is too large to fit through protein channels? | they are engulfed through endocytosis. |
| name and describe the two types of enocytosis. | pinocytosis-the engulfment of liquid phagocytosis-the engulfment of organic matter |
| where is phagocytosis especially common? | in unicellular eukaryotes |
| what cell in a human body uses phagocytosis and what do they engulf? | white blood cells engulf bacteria. |
| what is exocytosis? | the dumping of excretions or waste materials outsid a cell by discharging them from waste vacuoles that fuse with the plasma membrane. |
| what human cells use exocytosis and what do they secrete? | gland cells secrete hormones |
