Imagine an ecosystem in a temperate deciduous forest. The ecosystem has the following populations: producers
fruit trees
berry bushes
maple trees
oak trees
primary consumers
rabbits
butterflies
bees
deer
geese
chipmunks
termites
secondary consumers
foxes
owls
skunk
hawks
tertiary consumers
wolves
bears
2. Draw a food web representing the flow of energy in the ecosystem. Be sure to include all populations. If necessary, research each animal's diet to determine its place in the food web. Draw your web using a graphics program such as Word, Power Point, Publisher, or any other program you are familiar with.

Questions
Answer the following questions in full sentences and paragraphs, using at least 150 words, in the essay box below.

1. Which organisms are carnivores? Herbivores? Omnivores?
2. If the ecosystem is balanced, which populations should be the largest? The smallest?
3. Imagine a group of hunters kills half of the rabbit population. How will the other organisms be affected?
4. Imagine disease kills 85 percent of the wolf population. How will the other organisms be affected?
5. Imagine a foreign mountain lion species is introduced into the ecosystem. How will the other organisms be affected?

How does natural selection change thephenotypes within a population over time?

Experiments in environmental toxicology can sometimes be manipulative experiments in which the researcher actively chooses and manipulates the independent variable. in hunt's study, for example, dosages of bpa were manipulated and the effects were measured. in manipulative studies, the researcher controls all the other variables in the experiment, so any health effects observed in the test subjects can be attributed to differences in the independent variable. in other cases, researchers use natural experiments in which the dependent variable (typically a measure of organism health) is measured under differing contexts that are not manipulated. say, for example, that an accidental chemical spill contaminates five ponds. to determine the possible effects of the toxic chemical on frogs, a researcher could compare the hatching rate of frog eggs laid in those five ponds to the hatching rate of eggs laid in five uncontaminated ponds nearby. this would be an example of a natural experiment because concentrations of the toxic chemical in the ponds were not controlled by the experimenter, but rather resulted from the chemical spill. drag type of experiment on the left to the example of experiment on the right. blood concentrations of bpa in college students are compared to their recent manipulative consumption of canned food items 2. the feeding behavior of fish in streams that receive acidic runoff from strip mines is compared to the feeding behavior of fish in unaffected streams. the deformity rate in baby birds from nests in pesticide-sprayed fields is compared to the deformity rate in birds from nests in unsprayed fields 4 tumor development is compared in mice exposed to five dosages of a known carcinogen in the laboratory foraging activity levels are compared in tadpoles exposed to four concentrations of toxic metals in the laboratory. growth of corn plants is compared in field plots sprayed with three different dosage: s of weed killer 7 bpa concentrations in the urine of people with diabetes are compared to bpa concentrations in the urine of people without diabetes - natural; manipulative

Which process of living things produces water that enters the water cycle