How can a scientist best reduce the likelihood of reporting random errors in his measurements or data? a. the scientist should round all of the data to the nearest whole number to increase precision. b. the scientist should avoid using control groups, so there's no standard with which experimental data has to be compared. c. the scientist should perform one experimental trial and then eliminate any outlying data. d. the scientist should repeat the experiment several times to see if the same data is produced each time.

The gene that causes sickle-cell disease is present in a higher percentage of residents of sub-saharan africa than among those of african descent living in the united states. even though this gene causes sickle-cell disease, it also provides some protection from malaria, a serious disease that is widespread in sub-saharan africa but absent in the united states. discuss an evolutionary process that could account for the different percentages of the sickle-cell gene among residents of the two regions.

In german cockroaches, curved wing (cv) is recessive to normal wing (cv+). bill, who is raising cockroaches in his dorm room, finds that the frequency of the gene for curved wings in his cockroach population is 0.6. in his friend joe’s apartment, the frequency of the gene for curved wings is 0.2. one day joe visits bill in his dorm room, and several cockroaches jump out of joe’s hair and join the population in bill’s room. bill estimates that, now, 10% of the cockroaches in his dorm room are individual roaches that jumped out of joe’s hair. what is the new frequency of curved wings among cockroaches in bill’s room? 0.69 0.4 0.5 0.31 0.20

Of seawater increases with decrease in the temperature. therefore, the cold water sinks to the deeper layers at the bottom