Unit 1; cell membrane and scientific method Flashcards
Tonicity
consider the concentration of the dissolved solute. which way will the water flow?
isotonic
the same. concentration of the solute is equal inside and outside of the cell. water flows by osmosis at a constant rate in and out.
hypertonic
to much. A cell in a hypertonic environment will shrivel up. this is due to the fact that water flows to where the majority of the solute is and the solute is in greater amount on the outside then it is on the inside. water will leave by osmosis going from region of more water to less water.
hypotonic
to little. cell in a hypotonic environment will swell. this is due to the fact that the water will flow by osmosis to the region with the most solute. the solute is greater IN the cell and has less on the outside.
diffusion
movement of molecules from a region of high concentration to a region of low concentration.
osmosis
diffusion of water across a membrane
dialysis
diffusion of solutes across a membrane
osmotic pressure
pressure exerted on the hypertonic side ( where the water is going) pressure exerted on a side by the ability to draw water to itself. this pressure decreases over time because the solution gets diluted and its ability to draw water also decreases therefore decreasing the pressure.
hypothesis
testable statement or tentative explanation for an observation. you can test it and other scientists can repeatedly verify it.
theory
comes from well supported and tested hypothesis developed after extensive testing confirms the idea and it is falsifiable meaning that you can prove it wrong like a correction.
scientific method
ask a question, form a hypothesis, set up controlled environment to test it, analyze results, draw conclusions and have others test it.
parts of a hypothesis
dependant variable- observe or measure the results
indépendant variable- controlled variable
inventor of the microscope
anton von leuwenhoek
light microscopes
focus visible light rays
electron microscopes
TEM- shine a beam of electrons through specimen and shows a detailed image inside a cell
SEM scan a narrow beam of electrons across surface and creates a 3D