Sometimes tests for organic molecules are difficult to perform. For example, the color of the materials to be tested can affect the validity of the test. What would be the problem in testing grape juice (not grapefruit!) for protein?

The answer to this will be from your lab notes/procedure. it would be best to ask another student who participated in the lab as we do not know what was done, what enzyme or if the temperature is celsius or fahrenheit. if i were to guess though i'd say the rate stopped due to enzyme denturing at high temperature

Im not sure if you still need this but the answer is 300 hz450 hz  i just did this lesson so , wish you the best of luck and take care