Question

what are some limitations of using indicator liquids?
□ it is hard to use
□ depending on the initial color of the solution tested, it might be hard to analyze the results
□ if the levels of a certain substance are too low, it might not be detected and it can result in false negative
□ you can not know the concentration of a certain substance based on the final color

question 9
why do we call the four assays that detect macromolecules indicator liquids?
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12pt paragraph | b i u a | t² |

Explanation:

First Question (Limitations of Indicator Liquids)

• "It is hard to use" is too vague and not a specific limitation of indicator liquids.
• "Depending on the initial color of the solution tested, it might be hard to analyze the results" is a valid limitation because if the solution already has a color similar to the indicator's color change, interpretation is difficult.
• "If the levels of a certain substance are too low, it might not be detected and it can result in false negative" is correct as many indicators have a detection threshold and low concentrations may not trigger a visible change.
• "You can not know the concentration of a certain substance based on the final color" is true because indicator liquids typically show presence/absence or a range, not precise concentration.

Indicator liquids (like those used in macromolecule assays, e.g., Benedict's, Biuret, iodine, Sudan) are called so because they indicate the presence (or absence) of a specific macromolecule by producing a characteristic color change. For example, Benedict's reagent indicates reducing sugars by changing from blue to green/yellow/orange/red, iodine indicates starch by turning blue - black, Biuret indicates proteins by turning purple, and Sudan indicates lipids by showing red - orange droplets. Their primary function is to act as indicators (via color change) for the target macromolecule's presence during the assay.

Answer:

• Depending on the initial color of the solution tested, it might be hard to analyze the results
• If the levels of a certain substance are too low, it might not be detected and it can result in false negative
• You can not know the concentration of a certain substance based on the final color

Second Question (Why called Indicator Liquids)