The graph below shows the sources of some of the primary air pollutants generated by human activities. on the graph, "nox" represents nitrous oxides, "sox" represents sulfur oxides, "voc" stands for volatile organic compounds, "particulates" are small dust-like particles, and "co" is carbon monoxide. the release of sulfur oxides is a chief cause of acid rain. what human activity is primarily responsible for acid rain? a. fuel burning except in vehicles b. fuel burning in vehicles c. transportation d. industry

According to the law of conservation of energy, energy can neither be created nor destroyed. if this is true, why is there less energy in the top of the energy pyramid than there is in the bottom of the energy pyramid?

Parasitism could be considered a form of which of these types of relationships? -mutualism -commensalism -predator-prey -mimicry

To answer this question, researchers studied populations of the dusky salamander (desmognathus ochrophaeus) living on different mountain ranges in the southern appalachian mountains. the researchers tested the reproductive isolation of pairs of salamander populations by leaving one male and one female together and later checking the females for the presence of sperm. four mating combinations were tested for each pair of populations (a and b)—two within the same population (female a with male a and female b with male b) and two between populations (female a with male b and female b with male a). the proportion of successful matings for each mating combination was measured. for example, when all the matings of a particular combination were successful, the researchers gave it a value of 1; when none of the matings were successful, they gave it a value of 0. then the researchers calculated an index of reproductive isolation that ranged from 0 (no isolation) to 2 (full isolation). the reproductive isolation value for two populations is the sum of the proportion of successful matings of each type within populations (aa + bb) minus the sum of the proportion of successful matings of each type between populations (ab + ba). the table provides data for the geographic distances and reproductive isolation values for 27 pairs of dusky salamander populations.