When rodent populations become large and dense, a lot of fig…

When rodent populations become large and dense, a lot of fighting occurs.  (A) Some people have claimed that this is because in dense populations, individuals encounter many non-relatives.  Aggression is favored in these encounters with “strangers” as opposed to encountering kin and offspring in which cooperative behavior would be favored.  (B) Others have criticized this argument on the grounds that aggression in dense populations stems from the fact that individuals lack familiarity with those animals that they meet, not from any supposed reproductive advantage of being aggressive to non-relatives.  Define each of these explanations as either ultimate or proximate (make sure to explain your choice).  Is one explanation more correct than the other one?  In other words, should the two groups be arguing with each other?  Why or why not?

The chart below shows the percent change in mass of eggs in…

The chart below shows the percent change in mass of eggs in various salt solutions over a 1 hr period. By looking at the trajectory of the lines, you can tell if there was more or less salt in the egg in comparison to the solution based on whether water move out (it decreased in mass), or if water moved in (it gained mass). Based on the diagram, what percentage of salt is closest to the salt concentration in the egg, given the various lines for each percentage solution the egg was placed into?