All northern elephant seals come from a very small genetic pool. this is because in the 1890s a large number of them were very quickly killed until their population size was reduced to only about 20 individuals. though their population has since increased to over 30,000 individuals, all their genes have come from those 20 individuals. which of the following population genetic concepts does this example represent?
a. the founder effect
b. the bottleneck effect
c. the hardy-weinberg equilibrium
d. genetic drift

b. the bottleneck effect.

Explanation:

The bottleneck effect occurs when a population's size is reduced for at least one generation. This will result in a very reduced genetic variation, which can lead to further adaptation problems.

The Founder effect has its similarities (in terms of the resulting reduced genetic pool) with the bottleneck effect, BUT it occurs when a new colony is started by a few members of the original population.

The Hardy-Weinberg equilibrium is a principle in population genetics that states that the genetic variation in a population will remain constant from one generation to the next IF certain conditions are present (no migration, aleatory mating, among others), so this is not the answer.

Genetic drift (refers to the change in the frequency of an existing gene variant in a population due to random sampling of organisms, so it is not the answer.

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.