Final answer:
In a colorimetric analysis, the pt. cuvette typically contains both the reagent and the patient's serum. This mixture produces a measurable color change indicating the presence and concentration of certain substances in the serum.
Step-by-step explanation:
In colorimetric analysis, the contents of the patient's cuvette often include both the reagent and the serum of the patient. In this specific context, the correct answer is d) reagent + serum (pt. cuvette). The reagent is a chemical or mixture of chemicals used to react with the patient's serum (or analyte) to produce a color change. This color change can then be measured to determine the concentration of a particular substance in the serum. This is not to be confused with a titration, where a standard solution of known concentration is slowly added to another solution until the reaction reaches the endpoint, signaled by a color change with the help of an indicator.
In the pt. cuvette, the reagent is added to the serum to create a reaction that produces a color change. The color change is then measured using a colorimeter or spectrophotometer to determine the concentration of the substance.