Biology SPA: Enzymes
Experimental errors:
1. Not enough bubbling to from froth
- Inaccuracy in determining enzyme activity, result is lesser than expected
- Increase amount of specimen used such that there will be more enzymes working on the substrate
2. Heat loss to surroundings
- Enzymatic activity lower than expected, result is lesser than expected
- Use insulator container to minimize heat loss
3. Enzymes present in each specimen may vary
- Concentration may vary, results will be different from expected
4. Potato cubes floats up
- Cubes stuck at froth layer, blocks the formation of froth and destroys froth that was formed before, inaccuracy in reading, causing result to be higher than actual
5. Surfaces of potato stuck together
- Surface area for enzymatic reaction decreases, amount of froth produced is lesser than actual
Conclusions:
1. Rate of enzymatic reaction is the highest at its optimum temperature and it decreases as the temperature increases beyond its optimum temperature (temperature)
2. The higher the enzyme concentration, the faster the rate of the decomposition of the substrate(enzyme concentration)
3. The higher the temperature, the faster the rate of the decomposition of the substrate
Food tests:
Important food tests
Substances tested for
Chemical test
Procedure
Observation
Reducing sugars (except for sucrose)
Benedict’s test
1. add equal amt. of Benedict’s solution to the same amt. of reducing sugar solution
2. shake well
3. place test tube in boiling water bath with Bunsen burner on
- yellow => traces of reducing sugar
- orange => moderate
- red => a lot
Fats
Ethanol emulsion test
1. crush specimen into smaller pieces
2. add crushed specimen into test tube, followed by 2cm3 of ethanol
3. shake test tube well
4. allow solid particles of mixture to settle down, decant liquid portion of mixture, into another test tube containing 2cm3 of distilled water
- white emulsion=> lipids present
- no emulsion=> lipids absent
Proteins
Biuret test
1. add 2cm3 of egg white solution into test tube
2. add Biuret solution drop wise, shake after each drop
- lilac => proteins present
Starch
Starch test
1. add starch solution into test tube
2. add iodine solution into test tube
- blue-black=> starch present
- brown=> starch absent
Jordan.
With Love, Fourexpressone
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