Based on the hypothesis that ddt was causing a decline in fish-eating bird populations in the united states, a group of scientists predicted that the amount of ddt in bird eggs was correlated with the thickness of the egg shells. for their experiment, they planned to visit a number of fish-eating bird populations and take 1 egg from 70 nests. in the laboratory, they would open the eggs to measure the concentration of chemicals such as ddt. they would also measure the thickness of the egg shells. the researchers had to decide which species of birds they would use in their study. choosing the proper study organisms is very important because the species must be appropriate for the experiment, and practical to work with.

Two students are working together on an experiment that measures the effect of different liquid fertilizers on the thickness of plants’ stems. which is most likely to result in the greatest amount of error in their scientific experiment? a.one student measures the plant stem widths by using calipers. the other student measures the widths of the same plant stems again by using a different pair of calipers. b.one student measures the plant stem widths by using calipers. the other student types the measurements as they are taken into a computer spreadsheet. c.one student weighs liquids for the experiment by using a calibrated scale. the other student weighs liquids for the experiment by using a different calibrated scale.