Explain the difference between an endocrine cell and a target cell.

And endocrine cell is an outer cell i think and a target cell is an antibody which helps attack viruses

Six amino acids have side chains that are polar but not charged. these are serine (ser), threonine (thr), cysteine (cys), asparagine (asn), glutamine (gln), and tyrosine (tyr). these amino acids are usually found at the surface of proteins, as discussed in the proteins 2 module.

True statement gravity force is more on bigger mass, less on smaller mass.all mass fall on planet with same acceleration and speeds