What label goes in which location, I’m so confused right now?

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

When a person is exercising the body needs to deliver increased amounts of oxygen to the muscles which component of blood ensures that the muscles will receive it

Which of the following is a common response to cell signaling?