Cells Unit
UNIT 3:
CH 7:
CELLS
CELL STRUCTURE AND FUNCTION
Pg __
Name_________________________________Pr___
7.3 – CELL TRANSPORT Pages 196 – 207
1. Why are boarders important to cells?
____________________________________________________________________________________
Passive Transport
2. Every cells exists in a ____________ environment.
3. Although the outside of a cell can be quite chaotic, the internal conditions need to be relatively
_____________________.
Diffusion
4. Describe the movement of solute particle in a solution.
5. Define diffusion.
6. When particles have reached the same concentration on either side of a membrane, we say that they
have reached _____________________________.
a. True or false: at this point, the process of diffusion will stop. _________________
i. Why or why not? (see Figure 7-15).
Facilitated Diffusion
7. What are the two characteristics of molecules that easily pass across a cell membrane?
_______________________________________________________________________________
8. Define “facilitated diffusion.” ___________________________________________________________
___________________________________________________________________________________
9. Is facilitated diffusion specific? That is, do most channels only allow one kind of molecule to pass
through? __________________.
10. Does facilitated diffusion require energy? _________________
Osmosis: An Example of Facilitated Diffusion
11. What is the name of the protein channels that allow water to pass through a cell membrane?
_____________________________
a. Why are special channels needed for water?
_____________________________________________________________________________
12. Define osmosis. ______________________________________________________________________
 How Osmosis works
13. Look at the diagram to the right.
a. In which side is the concentration of the solute ( ) the greatest? _______
A
B
b. In which side is the concentration of the water ( ) the greatest? _______
c. The solute cannot move. The water can. The water will move from the area
of its highest concentration to the area of its lowest concentration. Which
way will it move? Side A to side B, or side B to side A? _________________
14. In its original state as shown in the picture, which side is hypertonic? ___________
a. Which side is hypotonic? ______________
b. After diffusion takes place, which side is isotonic? ____________________.
15. In the diagram to the right, the following words have been
eliminated. Find where they belong and write them in.
Hypertonic (solution)
Isotonic (solution)
Hypotonic (solution)
Plant cells
Animal cells
a. What do we call a plant cell that is “overstuffed” with
water? ____________
 Osmotic Pressure
16. What is osmotic pressure caused by? ____________________________________________________
17. Why are the cells in your body not harmed by osmotic pressure? ______________________________
___________________________________________________________________________________
18. Why are frog eggs in pond water not harmed by osmotic pressure?
____________________________________________________________________________________
19. Why are bacteria and plant cells not affected much by osmotic pressure?
____________________________________________________________________________________
Active Transport
20. Define Active Transport. _______________________________________________________________
21. Does active transport require energy? ____________
Molecular Transport
22. What sorts of materials are moved across a cell membrane by active transport?
__________________________________________________________
a. Give specific examples. __________________________________________________________
23. What biochemical are the pumps made of? _____________________
24. What happens to the proteins when ATP attaches to them? (Infer the answer from Figure 7-19.)
__________________________________________________
25. True or false: Your body uses a LOT of its energy to drive protein pumps. _________________
26. When active transport is in action, the materials moved are ___ (MORE concentrated, LESS
concentrated) on the side they are being moved to. (Circle one.)
Bulk Transport
27. What types of materials are moved by bulk transport? _______________________________________
 Endocytosis
28. What is the difference between phagocytosis and pinocytosis? ________________________________
____________________________________________________________________________________
____________________________________________________________________________________
 Exocytosis
29. What is the difference between exocytosis and endocytosis?
____________________________________________________________________________________
You do not need to answer the following in writing, but be sure you KNOW the answers!
Key Questions:
1. What is passive transport?
2. What is active transport?
Vocabulary:
Diffusion, facilitated diffusion, aquaporin, osmosis, isotonic, hypertonic, hypotonic, osmotic pressure