In active transport, materials move from an area of high concentration to an area of lower concentration (goes down the concentration gradient) and it requires or uses energy in the form of ATP (adenosine triphosphate)
I just took the test. The answer is climate
The hollow impression of a trilobite is an original remains fossil.
There are many reasons to why slaves were essential in the colonial economy:
Slaves were generally used more in the south, because large plantations were found there, which meant that the need for large amounts of workers.
Slaves provided cheap labors, and as they were not "citizens" of the US, they were not allowed their rights.
Slaves were also relatively easy to buy and replace, however, their survival rates were not that good after they traveled long distance.
etc.
hope this helps
