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30 Cards in this Set
- Front
- Back
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What is diffusion?
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Directional movement of molecules.
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What are the factors of diffusion?
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Direction-concentration, heat (temp.), & pressure; rate.
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What substance would diffuse faster? Why?
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One having a low molecular weight, because of the smaller size.
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Differentially permeable
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Membranes that are selective, "alive" and respond to their environment, allowing some molecules to pass and retards others.
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Nonpolar molecules
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Small, pass through membranes easily.
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Polar molecules
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Large, retained.
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Dialysis
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Seperation of dissolved substances by means of their unequal diffusion through a differentially permeable membrane.
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Phenolphthalein
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Turns red in basic solutions, a pH indicator.
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Iodine
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Turns yellow to dark blue, is a starch indicator.
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How does phenolphthalein change in the bag?
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From clear to hot pink and became basic.
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How does starch color change in bag?
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It turned dark purple and surrounding solution was yellow.
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Which molecules and ions does your experiment give evidence for passage through semipermeable membrane?
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Iodine, Na+, and OH-.
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Osmosis
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Diffusion of water across a differentially permeable membrane.
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Solution
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Liquid mixture of two or more kinds of molecules.
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Solvent
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Fluid that dissolves substances.
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Solute
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Substance dissolved in a solution.
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Hypotonic
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Solution with a lower concentration of solutes.
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Hypertonic
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Solution with a high concentration of solutes.
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Isotonic
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Two solutions that have equal concentrations of solutes.
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Golden Rule
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Water moves across semipermiable membranes out of hypotonic solutions.
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Did water move across the membrane in all bags containing solutions of sugar?
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No.
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In which bags did osmosis occur?
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Bag A,C,andD.
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Which bag represented the steepest concentration gradient relative to its surrounding environment?
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D.
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Did the greatest changes in weight occur in cells with the steepest concentration gradients? Why?
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Yes, because of higher concentration in bag.
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How does the slope of a segment of a curve relate to the rate of diffusion?
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Greater the slope the higher the rate of diffusion.
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What influence on diffusion causes the curves for bags C and D to become horizontal?
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Equal amount of solute in bag overtime.
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Plasmolysis
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Shrinking of the cytoplasm of a plant cell in response to diffusion of water out of the celland into hypertonic solution surrounding the cell.
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Why did the plant cells plasmolyze when immersed in a hypertonic solution?
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Water leaves the cell.
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What can you conclude about the permeability of the cell membrane and vacuolar membrane to water?
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Very permeable.
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What causes crispness in celery?
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Water molecules pressure cell wall, turgid.
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