For many centuries, legend has held that the loch ness monster, a dinosaur-like creature, exists in a lake in scotland. many hypothesize that the loch ness monster is a pleisiosaur, a lake-living dinosaur thought to have been extinct for millions of years. the majority of scientists do not believe this is possible. blurry photographs and video recordings show unusual shadows and movements in the lake, but no other signs of the loch ness monster have been recorded.

why do scientists dispute the claim that the loch ness monster is a real creature?
a) because there is no evidence of anything unusual in loch ness.
b) because the pleisiosaur hypothesis is not valid, as it is not based on reason.
c) because there is not a definite link between the pleisiosaur hypothesis and the evidence.
d) because in science, if a majority of scientists don't believe something to be true, a hypothesis is rejected.

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

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.

Which of the following describes a boom period? a. as one population increases, another population decreases. b. as one population increases, the other population also increases. c. as one population decreases, another population increases. d. as one population decreases, another population also decreases