2. Please describe what is an action potential, including depolarization, hyperpolarization, and repolarization. Please indicate the major ion driving the change in membrane potential in each phase.

32. In Figure below, the bacterial activator protein CAP and the Lac repressor have been placed in the four possible combinations on their binding sites in the promoter for the Lac operon. Each combination of gene regulatory proteins corresponds to a particular mixture of glucose and lactose. For each of the four combinations, indicate on the left-hand side of the figure which sugars (glucose or lactose) must be present (or absent) and, on the right-hand side, whether the operon is expected to be turned ON or OFF.

33. Using the figure on right, what is the first bond broken in the base excision repair process?

34. The E. coli chromosome contains 4,639,221 base pairs. How long would it take to replicate the E. coli chromosome at 37 °C if two replication forks proceed from the origin? Assume replication occurs at a rate of 1,000 base pairs per second. Under some conditions E. coli cells can divide every 20 min. How might this be possible? 

二、簡答題 1. If you aim to study the function of a gene in brain development, which model organism would you choose, and what experiments would you conduct to demonstrate the gene's function?

3. Given the latitudinal differences in sunlight intensity, how might you expect the carrying capacity of plant species found at the equator to compare with that of plant species found at high latitudes?

4. What is a biodiversity hot spot?

 1. Autotroph

2. Barr body

3. Biomass

4. Carbon fixation