Which statement describes a concentration assay using colored indicators to estimate protein concentration?

• A. Indicator test to determine the presence of a compound.
• B. Concentration assays use colored indicators to estimate protein concentration.
• C. Pharmacodynamic assays measure animal activity.
• D. Toxicology assays determine toxic quantities.

Answer: (B)

Colorimetric concentration assays for proteins rely on a reagent that changes color in proportion to the amount of protein present. The resulting color intensity is measured, usually as absorbance with a spectrophotometer, and a standard curve built from known protein concentrations lets you estimate the unknown amount in your sample. This approach is specifically about quantifying protein concentration, unlike indicators used merely to detect the presence of a compound, or assays that measure biological effects such as pharmacodynamics or toxicology.