Passage I
Agarose, a carbohydrate composed of galactose subunits, is found in the cell wall of some types of algae. Agarose can be broken down by the enzyme agarase. A student discovered a new form of agarase, Agarase X, in a species of bacteria. The student conducted the following experiments to determine the temperature and pH at which agarase X has the greatest activity.
Experiment 1
The student added 0. 2 mL of an Agarase X solution to each of 9 test tubes (Tubes 1-9), and then added to each tube 0.8 mL of a buffer solution (a solution that maintains a stable pH) having a pH of 7 and containing 0.2% agarose. Each of the tubes was incubated at a different temperature for 30 min, and the relative activity (percent of the greatest measured activity) of the Agarase X was determined for each tube (see Table 1).
Experiment 2
The student repeated the procedures used in Experiment 1 in every respect but the following: the test tubes (Tubes 10-18) received different agarose buffer solutions, each of a different pH, and all the tubes were incubated at 40°C. Once again, the relative activity of the Agarase X was determined for each tube (see Table 2).
5. In Experiment 1, among the following tubes, which tube most likely had the most agarose remaining at the end of the experiment?
Your Answer is
Correct Answer is D
Explanation
There is a lot of Agarose remaining, indicating that the relative activity is small and the reaction has not been carried out much. Look at table 1, the option with the smallest relative activity is D. Tube 9