1. Plant cells have cell walls and chloroplasts. A cell wall provides rigid support.

2. Plant cells have cell walls and chloroplasts. A cell wall provides rigid support. Chloroplasts convert solar energy to chemical energy.

3. KEY CONCEPT The cell membrane is a barrier that separates a cell from the external environment.

4. Cell membranes are composed of two phospholipid layers.

5. Cell membranes are composed of two phospholipid layers. The cell membrane has two major functions. cell membrane

6. Cell membranes are composed of two phospholipid layers. The cell membrane has two major functions. forms a boundary between inside and outside of the cell cell membrane outside cell inside cell

7. Cell membranes are composed of two phospholipid layers. The cell membrane has two major functions. forms a boundary between inside and outside of the cell controls passage of materials cell membrane outside cell inside cell

8. Cell membranes are composed of two phospholipid layers.

9. cell membrane Cell membranes are composed of two phospholipid layers. The cell membrane is made of a phospholipid bilayer.

10. Cell membranes are composed of two phospholipid layers. The cell membrane is made of a phospholipid bilayer. There are other molecules embedded in the membrane. carbohydrate chain protein cell membrane cholesterol protein protein channel

11. Cell membranes are composed of two phospholipid layers. The cell membrane is made of a phospholipid bilayer. There are other molecules embedded in the membrane. The fluid mosaic model describes the membrane. carbohydrate chain protein cell membrane cholesterol protein protein channel

12. Cell membranes are composed of two phospholipid layers.

13. Cell membranes are composed of two phospholipid layers. The cell membrane is selectively permeable. Some molecules can cross the membrane while others cannot.

14. Cell membranes are composed of two phospholipid layers. The cell membrane is selectively permeable. Some molecules can cross the membrane while others cannot.

15. Chemical signals are transmitted across the cell membrane. Receptors bind with ligands and change shape. There are two types of receptors.

16. Chemical signals are transmitted across the cell membrane. Receptors bind with ligands and change shape. There are two types of receptors. intracellular receptor

17. Chemical signals are transmitted across the cell membrane. Receptors bind with ligands and change shape. There are two types of receptors. intracellular receptor membrane receptor

18. KEY CONCEPT Materials move across membranes because of concentration differences. Diffusion and Osmosis

20. There are two types of passive transport.

21. diffusion

22. osmosis Diffusion and Osmosis

26. isotonic

27. hypertonic

29. Facilitated diffusion is diffusion through transport proteins. Diffusion and Osmosis

30. KEY CONCEPT Cells use energy to transport materials that cannot diffuse across a membrane. Active Transport, Endocytosis, and Exocytosis

32. Active transport is powered by chemical energy (ATP).

33. Active transport occurs through transport protein pumps.

35. Endocytosis is the process of taking material into the cell.

36. Phagocytosis is a type of endocytosis. Active Transport, Endocytosis, and Exocytosis

38. Exocytosis is the process of expelling material from the cell. Active Transport, Endocytosis, and Exocytosis