page 10 19. The population of the snail Vertigo antivertigo was investigated at a small site in Wales. Equal numbers of quadrat samples were taken in three areas with different dominant vegetation and the number of individual snails in each was recorded. The results are shown in the chart. 0 10 20 30 40 50 60 iris and rushes long grass short grass dominant vegetation in area quadrats (%) 1–7 individuals absent Key 40 or more individuals 8–39 individuals The information in the chart indicates that this species of snail prefers A short grass to long grass B irises and rushes to long grass C long grass to irises and rushes D short grass to irises and rushes. 20. Biological fieldwork often requires the estimation of population size for a prey species. One method used is mark and recapture. If the method of marking reduced the camouflage coloration of this species, what effect would this be likely to have on the population estimate obtained? A Recapture numbers would be increased and population size would be overestimated B Recapture numbers would be increased and population size would be underestimated C Recapture numbers would be decreased and population size would be overestimated D Recapture numbers would be decreased and population size would be underestimated