An open system, such as an ecosystem, is characterized by which trait?

a. energy enters the system but does not leave it.

b. energy neither enters nor leaves the system.

c. energy leaves the system but does not enter it.

d. energy can enter or leave the system.

Average annual precipitation and are the two major features that define the biomes on earth.

Johnny rode his bike to a friend's house 4 blocks down the street in his neighborhood. he immediately rode back home once he realized his friend was not able to play. what was his displacement for the total bike ride? how did you determine this? what could we use as a reference point to determine he was in motion during his bike ride? why can you use it as a reference point

Homo heidelbergensis was a tall, muscular hunter, who used both tools and weapons. because h. heidelbergensis was not a gatherer/forager, but ate a varied diet including meat and fish, we would expect to see what anatomical changes?