Biology – Testing for biological molecules | e-Consult
Testing for biological molecules (1 questions)
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Importance of Control Variables: Control variables are factors that are kept constant throughout an experiment to ensure that only the variable being tested (the presence of a non-reducing sugar) affects the outcome. Without controlling these variables, it would be impossible to determine whether any observed changes are due to the presence of the sugar or due to some other factor.
Three Examples of Control Variables:
- Concentration of the sugar solution: The same concentration of the sugar solution should be used for all samples being tested. This ensures that any colour change observed is due to the amount of reducing sugar present, not due to differences in concentration.
- Volume of acid used for hydrolysis: The same volume of dilute hydrochloric acid should be used for all samples. This ensures that the hydrolysis is carried out under identical conditions, leading to consistent breakdown of the sugar molecules.
- Temperature and time of hydrolysis: The acid hydrolysis should be carried out at the same temperature (typically 100°C) for the same duration (e.g., 10 minutes) for all samples. This ensures that the hydrolysis is complete and consistent across all samples.
- Concentration of Benedict's reagent: Using the same concentration of Benedict's reagent ensures that the same amount of copper(II) ions are available to react with the reducing sugars.