Warm air masses are dense than cooler air masses. Rains frequently occur when fronts meet because water vapor in the air rises, then and into clouds.

Calvin ate a candy bar, which caused his body's blood glucose levels to become unbalanced. his body responded by initiating a feedback mechanism to return his body to homeostasis. place the steps of this feedback mechanism in order, starting with the blood glucose imbalance that occurred after calvin consumed the candy bar. a) calvin's blood glucose levels decreased. b) calvin's pancreas stopped secreting insulin. c) calvin's body cells started to take up glucose and store it as glycogen. d) calvin's blood glucose levels increased. e) calvin's pancreas started secreting insulin.

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 which situations is the principle of cross-cutting relationship useful in determining relative age?