How can natural selection lead to speciation over thousands of years?

If a cell's main function is to produce proteins to be excreted, which organelles would you expect to be larger

Which medullary index indicates a human hair? a. 0.653 b. 0.733 c. 0.516 d. 0.256

Johnny rode his bike 4 blicks down the street to his friend's house once he got to his friend house and realized he could not cone out to play he turned aroubd and went back home.what is 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