A. Use the words below to complete the sentences.

Vocabulary
A selectively permeable membrane, Diffusion, Concentration, Osmosis


1) ____________ refers to the amount of a substance in a given space.

2) ______________ is the movement of particles from an area of higher concentration

to an area of lower concentration.

3) ________________ allows some materials to pass through it but keeps other

materials out.

4) ________________ is the diffusion of water molecules through a selectively

permeable membrane.

5) _______________ moves wastes from inside a cell to outside a cell.

6) _______________ can be compared to a window screen.

7) _______________ happens when water particles move from a place where their

concentration is higher to a place where their concentration is lower.

8) _______________ is the process by which oxygen is moved into and carbon dioxide

is moved into a cell.

Use the following diagram to answer questions 9 to 11


9) In which diagram(s) does water move into and out of the cell at the same rate? _____

10) In which diagrams(s) will the cell begin to swell? _____


11) Which diagram(s) shows what would happen if a cell were placed in salt water? ___

B. State whether each statement is true or false.

1. All living things have a specialized mechanism to exchange substances with their

environment. ____

2. Osmosis involves the movement of solute molecules. ____

3. The cell membrane is a selectively permeable membrane. ____

4. Chemicals in the air diffuse until evenly distributed. ____

5. A concentration gradient occurs when particles are evenly distributed in a region. ____

6. Diffusion occurs in the lung at the site of gas exchange in the alveoli. ____

7. Plants obtain carbon dioxide for photosynthesis through their roots. ____

8. A small surface area increases the rate of diffusion. ____

9. The tonicity is the comparative differences between the concentration of two solutions. ____

10. Red blood cells fight against infections caused by pathogens in the body. _____