Which of the following is an example of a mineral

How can antibodies "remember" a particular bacterial invader or "antigen" on that invader?

What is the term for the two sets of chromatids formed in the parent cell a.haploid b.diploid c.gamete d.tetrad

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