Optimisation of a PCR reaction is often a compromise between the competing demands for precision, efficiency and yield. Although the specific effects may vary, generally, increasing the annealing temperature will increase non-specific primer binding and reduce precision. Increasing the length of the elongation phase will reduce the proportion of incomplete newly-synthesised strands and therefore increase yield. In this case, the potential effect on efficiency is unclear. Increasing the elongation phase would increase the reaction time, but the time taken to ramp down to a lower annealing temperature would be reduced.

Which of the following techniques doesn’t involve use of a secondary antibody?

#Question id: 2222

#Unit 2. Cellular Organization

The solutions in the arms of a U-tube are separated at the bottom of the tube by a selectively permeable membrane. The membrane is permeable to sodium chloride but not to glucose. Side A is filled with a solution of 0.4 M glucose and 0.5 M sodium chloride (NaCl), and side B is filled with a solution containing 0.8 M glucose and 0.4 M sodium chloride. Initially, the volume in both arms is the same.

In the U-tube experiment illustrated above, which of the following statements correctly describes side B at equilibrium?

#Question id: 2223

#Unit 2. Cellular Organization

Five dialysis bags, constructed of a type of membrane that is permeable to water and impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were massed (weighed), and the percent change in mass of each bag was graphed.

 Which line in the graph represents the bag that contained a solution isotonic to the 0.6 M solution at the beginning of the experiment?

#Question id: 2224

#Unit 2. Cellular Organization

Five dialysis bags, constructed of a type of membrane that is permeable to water and impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were massed (weighed), and the percent change in mass of each bag was graphed.

Which line in the graph represents the bag with the highest initial concentration of sucrose?

#Question id: 2225

#Unit 2. Cellular Organization

Five dialysis bags, constructed of a type of membrane that is permeable to water and impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were massed (weighed), and the percent change in mass of each bag was graphed.

Which line or lines in the graph represent(s) bags that contain a solution that is hypertonic at 50 minutes?

#Question id: 2226

#Unit 2. Cellular Organization

What will happen to a red blood cell (RBC), which has an internal ion content of about 0.9%, if it is placed into a beaker of pure water?

#Question id: 2227

#Unit 2. Cellular Organization

Which of the following statements is most likely true of a protein that cotransports glucose and sodium ions into the intestinal cells of an animal?