DDT is an insecticide that was used extensively in agriculture in the mid-1900s to kill many insect pests including the boll weevil (pictured below), another pest of commercial cotton, DDT was initially effective at controlling boll weevil outbreaks, but after about a decade DDT became much less effective, because many populations of boll weevil had evolved resistance to DDT. Which of the following conditions would biologists say was required for the evolution of DDT resistance in a population of boll weevils? A) Boll weevils in the population learned to adapt to the high levels of DDT in the environment. B) The boll weevil population needed to evolve DDT resistance in order to avoid extinction C) A few boll weevils in the population were resistant to DDT before it was ever used. D) Exposure to DDT caused specific, nonrandom mutations for DOT resistance within the population.

Which of the following scenarios is an example of the bottleneck effect? answers a in south africa, much of the afrikaner population is descended from a small number of dutch colonists. in this population, this is an unusually high frequency of pseudoxanthoma elasticum (pxe), an elastic tissue disorder. b four white-tailed deer are introduced to a park in finland. thirty years after their introduction scientists compare the genes in the population and find that there is no variation. c during the industrial revolution, london's air became filled with soot. as a result, birds started eating more of the lighter moths because they were easier to spot than their darker counterparts. over time, the moth population changed so that there were more darker moths than lighter ones. d 10% of the population of american alligators in an area have the recessive trait albinism. a massive flood results in the death of 80% of the population. of the remaining population, 60% have the recessive trait of albinism.

2. given that most biochemical (other than coal) rocks react with hydrochloric acid, what does that tell you about organisms?

Explain why ecosystem diversity results in species diversity in a healthy biosphere