Stress can be measured by the amount of a certain chemical found in saliva. Subjects must be sure to get saliva samples twice a day at least 1 hour after eating or brushing teeth. In a study of 100 subjects, researchers tried to find a correlation between stress
levels and the wake up time of the individual. Which factor would NOT be an effective control that experimenters should add to
the experiment?
A) Subjects are given the same diet.
B) Subjects are selected in similar age groups.
C) Subjects are selected with the same occupation.
Eliminate
D) Subjects are awakened at the same time everyday.

Which of the following scenarios is an example of the bottleneck effect? answers a in south africa, much of the afrikaner population is descended from a small number of dutch colonists. in this population, this is an unusually high frequency of pseudoxanthoma elasticum (pxe), an elastic tissue disorder. b four white-tailed deer are introduced to a park in finland. thirty years after their introduction scientists compare the genes in the population and find that there is no variation. c during the industrial revolution, london's air became filled with soot. as a result, birds started eating more of the lighter moths because they were easier to spot than their darker counterparts. over time, the moth population changed so that there were more darker moths than lighter ones. d 10% of the population of american alligators in an area have the recessive trait albinism. a massive flood results in the death of 80% of the population. of the remaining population, 60% have the recessive trait of albinism.

This part insulates the reaction chamber from the transfer of heat to or from the surrounding environment

How do living things obtain phosphorus