QUESTION 9 Consider the plot above from an artificial selection experiment on fruit flies. Which of the following must have been true at the beginning of this experiment (generation 0 )? A new mutation had just arisen that caused flies to move away from the light. There must have been a single gene controlling the response of flies to light. There must have been preexisting variation in the response of flies to light. There must have been a population bottleneck leading to random fluctuations in behavior over time. In examining the DNA sequences of many human genes scientists have found they are very similar to the sequences of the same genes in chimpanzees. How can this be explained? A. chimpanzees evolved from humans. B. humans evolved from chimpanzees. C. DNA similarities evolved independently in humans and chimps. D. humans and chimpanzees share a relatively recent common ancestor. E. humans and chimpanzees are not closely related. Consider the plot above which shows the relationship been the mean size (SNV) of snakes in the population versus the time that populations of red-bellied black snakes in Australia have been exposed to poisonous cane toads. Given that researchers have multiple lines of evidence that this pattern is due to natural selection, which of the following is most likely NOT true? On average, snakes of any size are equally likely to survive and reproduce after ingesting a cane toad. Larger snakes have increased fitness compared to smaller snakes in populations exposed to toads. An increase in mean size is an adaptation to the presence of poisonous cane loads. There is variation in snake size, both within and among populations of snakes. Imagine you are studying a radioisotope with a half-life of 4 , 000 , 000 years. When the rock you are studying was formed, it had 200 radioisotope atoms. How many radioisotope atoms are expected to remain in the rock after 8 , 000 , 000 years? Fill in the blank with the correct number. Just provide the number without units..