Why is some cholesterol necessary for animal cell membranes but high cholesterol levels are dangerous?

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

[34 points awarded to the best answer, use facts and/or data] 1.) what's the likelihood of thunderstorms occurring in the state of maryland? {this question is for a project for science, use facts and/or data and explain why . 34 points to the best answer]

Which organisms udergo photosynthesis