2. Homeostasis Living things respond to their environment Cells maintain homeostasis by controlling the movement of substances across the cell membrane

3. Cell Membrane Composed of a phospholipid bilayer Polar Phosphate Head Two non polar fatty acid tails

4. Cell Membrane Hydrophobic – afraid of water Hydrophilic – water loving

6. The region in the middle (fatty acid tails) Repel ions and most polar molecules

7. Phospholipids are molecules that have A. One polar phosphate head and two polar fatty acid tails B. One polar phosphate head and two nonpolar fatty acid tails C. One polar phosphate head and one polar fatty acid tail D. One nonpolar phosphate head and two polar fatty acid tail

8. The interior of the lipid bilayer of a cell membrane forms a nonpolar zone that A. Allows most polar molecules to pass through the membrane B. Allows food to pass through the membrane C. Repels ions and most polar molecules D. Makes the membrane permeable to most molecules

9. Selectively Permeable Permeable – the ability of a substance to pass through an area Selectively Permeable –picking and choosing what can pass through Cell membranes are selectively permeable

10. Types of Transport Active Transport – requires energy in the form of ATP Passive Transport – does not require energy

11. Passive Transport Molecules of water and oxygen use passive transport to get into cells Diffusion - molecules move from high concentration to low concentration

12. As a result of diffusion, the concentration of many types of substances A. Always remains greater inside a membrane B. Eventually becomes balanced on both sides of a membrane C. Always remains greater outside of a membrane D. Becomes imbalanced on both sides of a membrane

13. Osmosis If water is moving from an area of high concentration to an area of low concentration through a membrane this is known as osmosis Has to be water!

14. Hypertonic – more water Hypotonic – less water Isotonic – water concentration is the same

15. Hydrophobic means A. Water fearing B. Water loving C. None of the above

16. The process of water moving through a membrane from high to low concentration is known as A. Diffusion B. Osmosis C. Phospholipid Bilayer D. Active Transport

17. The cell membrane is A. Completely permeable to all substances B. Selectively permeable C. Not permeable at all D. Only permeable to water

18. Which of the following does not require energy? A. Diffusion B. Endocytosis C. Active Transport D. Sodium-Potassium Pump