Describe each of the four mechanisms that cause air to rise.

The four mechanisms are as follows:
1) Orographic lifting: Air is forced to rise over a mountainous barrier

2) Frontal wedging: Warmer, less dense air is forced over cooler, denser air along a front 

3) Convergence: Pileup of horizontal air flow resulting in an upward flow
 
4) Localized convective lifting: Unequal surface heating causes localized pockets of air to rise because of their buoyancy. 

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.

They create genetic variations