Which type of vessel changes most to regulate resistance to blood flow. why?

Nerve cells are specialized to respond to stimulitrue or false?

Hemoglobin is a proton that carries oxygen around your body what is hemoglobin made from

Aragonite shells of clams, snails, or scleractinian corals may be preserved unaltered in cenozoic deposits, but they are generally dissolved or recrystallized in older deposits. true or false