The Anatomy and Physiology of Animals/Diffusion and Osmosis Worksheet 1

Chapter 3 The Cell

1. List 5 mechanisms by which molecules pass through the plasma membrane.

State whether these mechanisms are passive or active (ie use energy or not).

2. Which mechanism:
 * a.) uses no energy and results in an even distribution of molecules?
 * b) uses no energy, and occurs across a semi-permeable membrane?
 * c) occurs across the membrane of red blood cells causing them to swell and burst when placed in distilled water?
 * d) uses energy and allows the cell to take into itself particles and bacteria?
 * e) moves substances across the plasma membrane from a low to a high concentration?
 * f) uses a carrier molecule to help substances across a membrane but does not require energy?

3. Circle the correct statements below.

Diffusion is a process that:
 * a) occurs in liquid and gases
 * b) only occurs in liquids
 * c) uses energy
 * d) uses no energy
 * e) occurs naturally
 * f) occurs from a lower concentration of molecules to a higher concentration
 * g) occurs from a higher concentration of molecules to a lower one
 * h) results in an even distribution of molecules
 * i) only occurs with small molecules like water
 * j) is more rapid at low temperatures
 * k) is more rapid at high temperatures

4. Circle the correct statements below.

Osmosis:
 * a) is a special kind of diffusion
 * b) only occurs in gases
 * c) is not a natural process
 * d) is the diffusion of water molecules only
 * e) is the diffusion of water molecules from a high concentration of water to a low concentration of water
 * f) requires a semi-permeable membrane
 * g) requires energy
 * h) results in an even dispersal of water molecules
 * i) results in an even distribution of salt molecules

5. A semi-permeable membrane is a membrane that:
 * a) allows some molecules to go through but not others
 * b) allows all molecules to go through
 * c) is different on each side
 * d) is partly made from permeable compounds

6. Active transport:
 * a) uses energy
 * b) uses no energy
 * c) occurs from a lower concentration of molecules to a higher concentration
 * d) occurs from a higher concentration of molecules to a lower one
 * e) results in an even distribution of molecules
 * f) only occurs with small molecules like water

7. Oxygen crosses the plasma membrane by:
 * a) diffusion via the channels
 * b) active transport
 * c) diffusion through the lipid bilayer
 * d) facilitated diffusion
 * e) osmosis

8. Water crosses the plasma membrane by:
 * a) diffusion via the channels
 * b) active transport
 * c) diffusion through the lipid bilayer
 * d) facilitated diffusion
 * e) osmosis

9. Lipid soluble molecules cross the plasma membrane by:
 * a) diffusion via the channels
 * b) active transport
 * c) diffusion through the lipid bilayer
 * d) facilitated diffusion
 * e) osmosis
 * f) pinocytosis
 * g) phagocytosis

10 Sodium ions move from a low to a high concentration across the plasma membrane by:
 * a) diffusion via the channels
 * b) active transport
 * c) diffusion through the lipid bilayer
 * d) facilitated diffusion
 * e) osmosis
 * f) pinocytosis
 * g) phagocytosis

11 Glucose molecules cross the plasma membrane by:
 * a) diffusion via the channels
 * b) active transport
 * c) diffusion through the lipid bilayer
 * d) facilitated diffusion
 * e) osmosis
 * f) pinocytosis
 * g) phagocytosis

/Worksheet Answers/