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Chapter 4 – The Cell in Action
Section 1: Exchange with the Environment
1. How does the movement of materials across the cell membrane relate to an organism’s
survival?
This movement of materials helps keep cells healthy so they can divide. Cell division then allows
organisms to grow and repair injuries.
What is diffusion?
2. The movement of particles from areas of high concentration to areas of low concentration is
called diffusion.
3. The fluids that surround and fill a cell are made mostly of water.
4. Water is made up of particles called molecules.
5. The diffusion of water through semipermeable membrane is called osmosis.
6. Describe what happens in osmosis.
Water particles move to where they are less concentrated.
7. Why is osmosis important to cell functions?
because it helps maintain a balance within the cell of all the concentrated particles
8. Describe what would happen if you put red blood cells into a salty solution.
The water will move out of the cells to where water molecules are less concentrated in the salty
solution. The cells will shrivel up because they are losing water.
9. Describe what happens to a wilted plant when it is watered.
Through the process of osmosis, water moves into the plant cells, which makes the plant firm
again.
Moving Small Particles
Match the correct description with the correct term. Write the letter in the space provided.
10. particles moving across a cell membrane without using energy - C
11. passageways in a cell membrane - A
12. the movement of particles from an area of low concentration to an area
a. channels
b. active transport
c. passive transport
of high concentration across a cell membrane - B
13. two examples of passive transport - D
d. diffusion and
osmosis
e. energy
14. what a cell needs to transport particles by active transport - E
15. The channels in a cell membrane are made up of proteins.
Moving Large Particles
16. A large particle can enter a cell by an active-transport process called endocytosis.
17. What happens to a cell during the process of endocytosis?
The cell surrounds a large particle and encloses it in a vesicle to bring the particle into the cell.
18. A large particle can leave a cell by an active-transport process called exocytosis.
19. What happens to a cell during the process of exocytosis?
The cell forms a vesicle around the large particle and carries the particle to the cell members. The
vesicle fuses with the membrane and releases the particle outside the cell.
Use the figures below to answer questions 20 and 21.
20. In what order would the figures demonstrate exocytosis?
The particle would move from the inside of the cell to the outside of the cell. C, A, B
21. In what order would the figures demonstrate endocytosis?
The particle would move from outside the cell to the inside of the cell. B, A, C