Q1. We estimate the size of a population of small mice in a particular field by the mark-response method. Our estimate is 350. Later, we learn from experiments on the behaviour of these mice that they can locate a baited trap faster if they have already been rewarded with food by visiting that trap once before. Does this mean that our original estimate of 350 individuals was too low or too high? Give details the answer in terms of the principles that underline the mark recapture method.

Q2. Lack of iron in photic zone of the open ocean restricts the size of plankton populations. Iron is what kind of factor for marine plankton?