If rats are allowed to wander through a complicated maze, they will subsequently run the maze with few errors when a food reward is placed at the end. their drastic change in performance once given a reward describes

b. the carbon cycle ensures living things have a source of hydrogen

scientists have discovered that hiv does not cause aids by the virus's direct effect on the host's immune cells, but rather through the cells' lethal influence on one another. researchers from the gladstone institutes have revealed that hiv does not cause aids by the virus's