Which is an example of an internal stimulus?

a) a sudden change of air temperature

b) an artificial light that attracts insects

c) an increase in the amount of water available to a plant

d) a decrease in oxygen levels in the blood during exercise

Why are small quantities of chlorofluorocarbons so harmful to the ozone layer? a. the chlorofluorocarbons act like ultraviolet radiation causing large amount of ozone to be produced. b. the chlorine from the chlorofluorocarbons reacts with free molecules of oxygen causing a stop in ozone production c. free oxygen atoms can replace the chlorine in chlorine monoxide, releasing a free atom of chlorine which can then recombine with an oxygen atom in ozone, destroying more ozone. d. chlorofluorocarbons absorb ultraviolet radiation, preventing the formation of ozone select the best answer from the choices provided

Humans are believed to have evolved in coastal regions in east africa. the region had an abundant supply of fish for early humanoids to eat. when scientists analyze the fads gene they see an interesting pattern. people whose families have lived in this area of east africa for generation show a high level of diversity in alleles for the fads gene. conversely, people whose families had migrated inland a moderate distance from sources of fish showed a much lower diversity for fads gene alleles. additionally, the fads alleles found in people whose family has lived inland for generation are almost all gene alleles which produce fads proteins with a high level of function and activity. how do anthropologists explain this?

During the day, plants produce by splitting water molecules in the light-dependent reactions of photosynthesis. at the same time, plants use cellular respiration to produce some of the needed by the light-independent reactions to make sugars. during the night, plants produce because takes place.