Which of the following is a biotic factor that regulates population size in an ecosystem?

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 and independent assortment are important activities that occur during meiosis. what is the significance of these activities

The relationship between intron and exon