Some sample essay questions from an old exam 1. Match the story in the table with the process it describes. Each story is associated with only one process, so do not write more than one letter per story! A process can be described once in the table, more than once, or not at all, so letters may be used 0, 1, or >1 times. PROCESSES A. Gene flow C. Stabilizing selection E. Disruptive selection B. Genetic drift D. Directional selection STORIES PROCESS Rainbow Pooper Mice (RPMS) live in Switzerland. They have that name because their feces come in very bright colors. In the native population, 40% of RPMS produce bright blue feces, and 60% produce green feces. This trait is heritable. On a trip to Switzerland, you decide to smuggle some back to Long Beach to start your own population. You grab the first five mice you see and hide them in your luggage. When you get back to Long Beach, you notice that you happened to grab only mice that produce green feces... so your new population is 100% green poop-producing, very different from the original population. Two populations of guppies live in a river, one in the upstream part, and one about 20 kilometers downstream. There is normally no movement of guppies between these populations. After a big rainstorm, the river was flowing unusually vigorously, and it carried a few members of the upstream population down into the downstream population, where they found mates and started raising their guppy families. Yellow-bellied toads make a toxic yellow protein, and store it in their skin. The more of this protein they make, the brighter their skin. The amount of toxin an individual toad makes is heritable. When predatory birds are looking for toads to eat, they selectively eat the ones that have the least bright skin. In a population of chickens in Arkansas, there is heritable variation in eggshell thickness. Eggs with very thin shells break as soon as they are laid, killing the chick inside. However, if the eggs have very thick shells, the chick inside is unable to break a hole in the egg in order to hatch, and so these die as well A field in Malibu contained a small population of wild sunflowers. Some individuals in this population had white flowers, some orange flowers, and some red flowers. Unfortunately, a celebrity bulldozed most of the field last year so that he could build giant mansion in the middle of it. While bulldozing the habitat, most of the sunflowers were killed, including all of those with the allele for red pigmented flowers. Now the population only includes flowers with white or orange flowers. a Tiny Soda Mice (TSMS) can only nest in one place: in empty soda cans. TSM8 that are bigger than about 2 cm in body diameter can't fit into soda cans. Those large TSMS nest on open ground, but they almost always get eaten by snakes before producing offspring.