What types of organisms were first placed in the kingdom protista

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

Crossing over is a method of (blank)?

Why did the federal government end its support of yucca mountain as a site for long-term storage of nuclear water