Test for starch in a leaf

b)

• To kill the leaf cells and stop all chemical reactions.
• To break down the cell walls and membranes, making them permeable to iodine solution.

c)

i) The leaf in the dark turned pale brown because it did not photosynthesize and therefore did not produce or store starch. Iodine solution gives a pale brown color in the absence of starch.

ii) The leaf in the light turned blue-black because it photosynthesized and produced starch. Iodine solution turns blue-black in the presence of starch.

4. Hazard symbols

a)
A: Oxidizing
B: Flammable
C: Toxic
D: Harmful/Irritant
E: Environmental Hazard

b)
A (Oxidizing): Hydrogen peroxide, Potassium permanganate
B (Flammable): Ethanol, Acetone
C (Toxic): Cyanide, Mercury compounds
D (Harmful/Irritant): Bleach, Ammonia
E (Environmental Hazard): Pesticides, Heavy metals

c)

• Fuel stations
• Laboratories (for storing flammable solvents)