The Nature of Science Note: Iodine solution reacts chemically with starch to form a blue-black product.
Water +
Iodine
Visking tubing
Starch solution Tube A
Initial colour inside tube Final colour inside tube Initial colour of liquid in beaker Final colour of liquid in beaker
Questions 1. Why did the starch solution in the visking tubing in beaker A eventually turn blue- black?
Permeability The degree to which substances can pass through something.
2. Why did the water in beaker A not turn blue-black? 3. What does this tell you about the permeability of visking tubing? 4. Was there any change inside or outside the visking tubing in beaker B? 5. Was there any difference in the fullness of the tubes? Can you explain this? 6. What does this experiment tell you about the structure and function of a cell membrane?
7.4 Cell organisation Cell
Tissue Water Tube B
Organ
System
Muscle cell
Muscle tissue
Stomach Fig. 12 Cell organisation 68
In multicellular organisms, cells must work together to carry out their function(s). A group of cells working together is called a tissue. Examples of animal tissues include nerve tissue and muscle tissue. Nerve tissue carries messages around the body. Muscle tissue enables the body to move. Examples of plant tissues include xylem tissue which transports water, and phloem tissue which transports food.
