Is oxygen a requirement of all living things?

After fertilization, which type of cellular division is responsible for the growth and development of a complex, multicellular organism?

Of seawater increases with decrease in the temperature. therefore, the cold water sinks to the deeper layers at the bottom

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