Layout References Malings Review e Help VTel me what you wht to t can contain vi

Question

Layout References Malings Review e Help VTel me what you wht to t can contain viruses Unless you need to edit, it's safer to stay in Protected View Enable Editing [4] A colony of German cockroaches in your cabinet is growing at a monthly intrinsic rate of r- 2 roaches/roach/month. The size of the population grows for 9 months rapidly and then levels off for the last 3 months to 100. A dose of insecticide kills 60 % of the roaches. You would predict that, after another month, the size of the colony would be... a) 48 b) 80 c 88 d) 100 120 [5) The generation whose size you just calculated is sprayed with the same dose of insecticide, and none are killed. You would hypothesize that all roaches survived most likely because... a) insecticides can never kill multiple generations of roaches b) roach genes in the new generation mutated to resist insecticide c) the roaches who survived had inherited genes for insecticide resistance. d) natural selection had randomly acted to benefit a select group of roaches e) young roaches adapted by learning from their parents to avoid ingesting insecticide. [61 During the summer of 1998 a drought hit Oklahoma, resulting in the decrease of the level of Theta Pond by evaporation and a drastic rise in salinity (salt concentration): Soon 72% of the goldfish died because they are not adapted to live in a high saline concentration. This would be described by a population biologist as a decline in the eoldfish nonulation. 8 0

Explanation / Answer

1) 120 - The population of the cockroaches after the growth rate leveled off was 100. Hence, when 60% of the population are killed by insecticides, only 40 cockroaches will be left. The r - intrinsic rate of population increase is the per capita rate of increase in population, which equals birth rate minus death rate. The r was 2 roaches/roach/month. By calculating with the same intrinsic rate, 40 cockroaches will each produce 2 cockroaches in a month which totals to 3 in a single family. When, 40 cockroaches each produce 2 cockroahes, then 40*3 = 120.

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