Practical Tests

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Drawings

• Make sure you use a sharp pencil 

• Your outline is clear 

• The drawing should be as large as space provided.

• It has definite outlines (no 'sketchy‘ lines)

• No shading,

• No arrowheads when labelling

• Lines point exactly at the labelled part.

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Enzyme Activity

Method:

• Put 3cm2 of hydrogen peroxide in a test tube.

• Add fresh potato strips and shake gently.

• Keep your thumb on top of the test tube, or use a stopper, to retain the gas.

• Do the “glowing splint” test → the splint relights.

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Chemical Tests

• Starch: Add few drops of iodine, +ve result = blue-black color

• Reducing sugars: Add Benedict’s reagent, then mixture is heated in water bath for 2 to 3 

minutes. 

• +ve result (increasing concentration of sugar) = blue  green  yellow  orange  red

• -ve result = remains blue

• Proteins: Add few drops of Biuret reagent, +ve result = mauve color, -ve result = remains blue

• Fats: Emulsion test; ethanol is added to mixture, and this is poured into a test tube with an 

equal amount of distilled water, +ve result = milky-white emulsion

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Photosynthesis

Light intensity:

First, a lamp is placed as close as possible to 

the apparatus, then the experiment is repeated several 

times, each time with the lamp further away from the 

apparatus. Heat from the bulb is prevented by placing a clear 

glass sheet between the lamp and the apparatus, and the 

pondweed used is left for several minutes in each new light 

intensity to allow it to adjust to new conditions before the rate is 

measured.

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