18. The red line represents the actual bear population, while the blue line shows the predicted population. Why doesn't the actual bear population ever match the exact
carrying capacity?

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.