Jordan has an organic garden. he is designing an experiment to determine if a mineral-oil bug spray made of garlic and habanero peppers is more effective on japanese beetles than one made with just garlic. how could jordan improve his plan for the experiment as outlined below?

1. prepare bug sprays—being sure to document ingredients in each type.
2. determine which plants will be sprayed and section off two groups.
3. spray every morning at 8: 30 a. m.
4. record number of beetles on each group at the same times every day.
5. record significant rain or weather events that may affect application of the sprays.
6. photograph damage on both groups of plants at the end of the trial.

a. he should account for all the beneficial insects he accidentally kills.
b. he should include a control group which receives no spray.
c. he should prepare several variations on each spray's recipe.
d. he should remove all living beetles after each counting.

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

What would most likely happen if a person increased the amount of saturated fat in his or her diet? the person's risk of cardiovascular disease would increase. the person's risk of cardiovascular disease would decrease. the person's bad cholesterol would decrease. the person’s good cholesterol would increase.

Which of the following is the earliest era of earth's geologic time scale? cenozoic mesozoic precambrian paleozoic