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Osmosis and Solutions Name _____________________ Date ___________ Period _____ Use the information in the book to complete this worksheet. The information to help you with this sheet can be found in Chapter 9. Be certain to use complete, detailed sentences to define the words below and answer the questions in order to receive credit. 1. Diffusion – 2. Osmosis – 3. Hypotonic solution – 4. Hypertonic solution – 5. Isotonic solution – 6. Turgor pressure – 7. In a hypotonic solution, how will water molecules move? 8. In a hypertonic solution, how will water molecules move? 9. In an isotonic solution, how will water molecules move? 10. Explain how hypotonic and hypertonic conditions will make a plant stand up straight or make it wilt. What is going on in the plant? 11. If osmosis refers to the movement of water molecules, what are the names used for the movement of dissolved particles? 12. What structures are involved in the movement of dissolved particles? 13. What do unsaturated fats do to the cell membrane? Use the diagrams below and information in your book to answer the following questions:
14. Look at the u­shaped tube. Why did the number of water molecules on each side of the membrane change after osmosis, while the number of sugar molecules stayed the same? 15. How does the plasma membrane of a cell compare with the membrane in the u­shaped tube? 16. Explain the behavior of the molecules in the isotonic solution. 17. Does osmosis occur if a cell is placed in an isotonic solution? 18. Why does water enter a cell placed in a hypotonic solution? 19. What happens to the turgor pressure of a cell placed in a hypertonic solution? 20. What can happen to animal cells in a hypotonic solution? 21. How do protists survive in a hypotonic environment? Use the information found on the web­site in order to answer the following questions http://www.biologycorner.com/bio1/diffusion.html 22. What is the concentration gradient? 23. What does it mean to go with the concentration gradient?
24. What does it mean to go against the concentration gradient? 25. What does selectively permeable mean? 26. What 2 compounds move freely across the cell membrane? 27. What does Iso­ mean? 28. Which way do the water molecules move in an isotonic solution? 29. Explain what happens to a plant cell in a hypotonic solution. 30. Explain what happens to an animal cell in a hypotonic solution. 31. Explain what happens to plant cells in a hypertonic solution. 32. Explain what happens to animal cells in a hypertonic solution. 33. Why is it dangerous to drink sea water? 34. Name two types of passive transport. 35. What is facilitated diffusion? 36. What structures help move large molecules cross the cell membrane? 37. What is active transport? 38. Give an example of active transport? 39. What is endocytosis? 40. What is exocytosis? Check out this animation of exocytosis: http://www.stanford.edu/group/Urchin/GIFS/exocyt.gif Use this web­site in order to fill in the notes: http://sps.k12.ar.us/massengale/homeostasis_notes_bi.htm
I. Cell Membranes A. Cell membranes help organisms maintain __________________________ by controlling what substances may enter or leave cells B. Some substances can cross the cell membrane without any input of energy by the cell C. The movement of such substances across the membrane is known as __________________________________ D. To stay alive, a cell must exchange materials such as food, water, & wastes with its environment E. These materials must cross the _____________________________ F. Small molecules like _____________________________________ can move in and out freely G. Large molecules like _____________________________________ cannot move easily across the plasma membrane H. The Cell Membrane is ____________________________________ only allowing certain molecules to pass through IV. How Cells Deal With Osmosis A. The cells of animals on land are usually in isotonic environment (equilibrium) B. Freshwater organisms live in hypotonic environments so water constantly moves into their cells C. Unicellular freshwater organisms use energy to pump out excess water by ______________________________ D. Plant _________________________________prevent plant cells from bursting in hypotonic environments E. Some marine organisms can pump out excess salt V. Facilitated Diffusion A. Faster than simple diffusion B. Considered passive transport because extra energy not used C. Occurs down a concentration gradient D. Involves ________________________________embedded in a cell’s membrane to help move across certain solutes such as _________________________
E. Carrier molecules change shape when solute attaches to them F. Change in carrier protein shape helps move solute across the membrane G. Channel proteins in the cell membrane form tunnels across the membrane to move materials H. Channel proteins may always be open or have gates that open & close to control the movement of materials; called gated channels I. Gates open & close in response to concentration inside & outside the cell VI. Active Transport A. Requires the use of ____________________ or ________________________ B. Moves materials _____________________________________________________ from an area of lower to higher concentration C. May also involve membrane proteins D. Used to move ions such as Na + , Ca + , and K + across the cell membrane E. Sodium­Potassium pump moves 3 Na + out for every 2 K + into the cell 1. Causes a difference in charge inside and outside the cell 2. Difference in charge is called membrane potential F. Ion pumps help __________________________________________ G. Plants use active transport to help roots _______________________________________ (plant nutrients are more concentrated inside the root than outside) VII. Bulk Transport A. Moves large, complex molecules such as proteins across the cell membrane B. Large molecules, food, or fluid droplets are packaged in membrane­bound sacs called vesicles C. ______________________________ moves large particles into a cell
D. Phagocytosis is one type of endocytosis 1. Cell membrane extends out forming pseudopods (fingerlike projections) that surround the particle 2. Membrane pouch encloses the material & pinches off inside the cell making a vesicle 3. Vesicle can fuse with lysosomes (digestive organelles) or release their contents in the cytoplasm 4. Used by ameba to feed & white blood cells to kill bacteria 5. Known as "cell eating" E. Pinocytosis is another type of endocytosis 1. Cell membrane surrounds fluid droplets 2. Fluids taken into membrane­bound vesicle 3. Known as "cell drinking" F. ________________________________________ is used to remove large products from the cell such as wastes, mucus, & cell products G. Proteins made by ribosomes in a cell are packaged into transport vesicles by the Golgi Apparatus H. Transport vesicles fuse with the cell membrane and then the proteins are secreted out of the cell (e.g. insulin)