Biological Molecules Testing Quiz
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5 questions, one answer each
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1. Which colour change indicates a positive result when carrying out the Benedict's test for reducing sugars?
- A. Blue to brick-red precipitate
- B. Yellow-brown to blue-black
- C. Blue to purple
- D. Colourless to milky white
2. A student adds iodine solution to a food sample and observes a blue-black colour change. Which biological molecule is present?
- A. Reducing sugar
- B. Starch
- C. Protein
- D. Lipid
3. The Biuret test is used to identify which biological molecule?
- A. Lipids
- B. Starch
- C. Proteins
- D. Reducing sugars
4. A student performs the ethanol emulsion test on a sample of vegetable oil. What observation would confirm the presence of lipids?
- A. A brick-red precipitate forms
- B. The solution turns blue-black
- C. A milky white emulsion forms
- D. The solution changes from blue to purple
5. A student uses a colorimeter to measure the intensity of colour change in a Benedict's test. How would this quantitative data improve the interpretation of results compared to visual observation alone?
- A. It would allow the student to identify which biological molecules are present
- B. It would provide a numerical measurement of colour intensity, enabling more precise comparison and detection of small differences in reducing sugar concentration
- C. It would eliminate the need to use the correct temperature
- D. It would determine which food test to use next