During urine formation, what happens to a substance that is not filtered or reabsorbed, but secreted?

Why is it important for an organism to maintain temperature, salt concentrations, and pH within a narrow range?

Which of the following is a basic requirement for natural selection to be an effective evolutionary force?

Which of the following is not used by systematists to distinguish one species from another?

What is the role of amylase in digestion?

Which of the major adaptations of angiosperms is most vulnerable to herbivore attack, especially by insects?

The variations on which natural selections works are produced by __________.

Which of the following statements about feedback systems is true?

You are a biologist studying a natural population of mice, and you observe that, in one area, the proportion of darker-colored mice is greater than the proportion of lighter-colored mice. In another area, the opposite is true. You find that only the area with more dark mice has predators. Therefore, you hypothesize that darker mice are favored in areas with predators, perhaps because they are more difficult to see. If your hypothesis is true, what would you expect to happen in the few generations after predators are introduced to an area with a population of mice that previously did not have predators?

The vast majority of animal species __________.