Why is the cell membrane made up of a phospholipid bi-layer considered semi-
permeable?

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

(amoeba sisters video recap: pedigrees and need

Has regulatory areas for thirst, hunger, body temperature, water balance, and blood pressure