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Virtual Lab – Osmosis – Tonicity in Elodea Cells (Plant Cells) When the solute concentration is greater on one side of the membrane, the environment with the greater solute concentration is known as the _____________________ environment.

Virtual Lab – Osmosis – Tonicity in Red Blood Cells (Animal Cells) Normal red blood cells have a solute concentration of 1%. When the environment contains 1% solute, the cell is in an isotonic environment. When the environment contains a solute concentration greater than 1%, the cell is hypotonic compared to the environment (the environment is hypertonic).

Virtual Lab – Osmosis – Tonicity in Elodea Cells (Plant Cells) When solute concentration is equal across the membrane, it is known as an ________________ condition.

Virtual Lab – Diffusion Across a Selective Permeable Membrane Why don’t we need to use a strip to test for the presence of starch inside or outside the dialysis tubing?

Molecules move across the selective barrier called the plasma membrane according to their physical and chemical properties. If this process is driven by the potential energy stored in the form of a concentration gradient, it is called passive transport. Passive transport occurs without any additional energy supply by the cell. Molecules move from an area of higher concentration to an area of lower concentration in a process called diffusion. In the first virtual lab activity, we use an artificial membrane called dialysis tubing to mimic the cell membrane. Dialysis tubing is made of cellulose (polymer of glucose) and it acts as a semipermeable barrier much like a real cell membrane. It is selective for which molecules can pass through the dialysis membrane simply based on the size of the pores found in the wall of the membrane. Small molecules will be allowed to pass through while blocking larger molecules.

Virtual Lab – Osmosis – Tonicity in Red Blood Cells (Animal Cells) Correlate each picture to the tonicity (isotonic, hypertonic, hypotonic) 0% NaCl 0.9% NaCl 10% NaCl [word1] [word2] [word3]

Virtual Lab – Osmosis – Tonicity in Red Blood Cells (Animal Cells) Why do blood cells in 10% NaCl solution crenate?

Dialysis tubing is a selectively permeable membrane made with the macromolecule, cellulose. Starch, glucose, water and the IKI reagent arecontained within the dialysis membrane in solution B shown below. Solution A in the beaker, at the start of the experiment in panel (a) contains just water. Diffusion of these molecules occurs, over time, from panels (a)-(c). The only selective criterion for diffusion across a dialysis membrane is the size of the molecule. Between water, (H2O), iodine (I2K; aka IKI), glucose (C6H12O6), and starch (50+(C6H12O6), which molecule is considered large and therefore likely not to pass through a dialysis membrane (Look at the image above, as time progresses, for help)?

Virtual Lab – Osmosis – Tonicity in Elodea Cells (Plant Cells) What causes the cytoplasm of Elodea cells to shrink in size when placed in a hypertonic solution (10% NaCl)?

Virtual Lab – Osmosis – Tonicity in Elodea Cells (Plant Cells) Use the word bank to label the corresponding numbers in the table below. Nucleus Nucleolus Cell Wall Chloroplast   1. [word1] 2. [word2] 3. [word3] 4. [word4]