Once the ACH is broken down the sarcoplasmic reticulum reabsorbs the calcium and Na+ is pumped back out of the cell. which step in muscle contraction is this?​

The observations of hooke and van leeuwenhoek documenting the existence of microscopic cells formed the basis of what important theory? a. the cell theory stating that all living things are composed of cellsb. the theory of spontaneous generation, which held that life forms could arise spontaneouslyc. the theory of chemotherapy, or use of antimicrobials to destroy pathogenic organismsd. the germ theory of disease and causative agents

The intervention of extraterrestrials has been used to explain the bermuda triangle, a region of the atlantic ocean where ships and planes are frequently lost, leaving no evidence behind. how would this explanation best be characterized?

What are the fixed alleles in the human species? o a. the alleles that are on the most chromosomes b. the alleles that change most often 000 c. the alleles that no one has d. the alleles that everyone has