One of SAM's gas chromatograph columns is chiral: it can separate left-handed molecules from right-handed ones. Terrestrial life uses amino acids that almost all one handedness, while Earthly sugars are mostly the other. Finding a similar pattern on Mars would be a smoking gun demonstration of extraterrestrial life.
Exactly this. We'd expect for random abiotic organic chemistry to yield racemic mixtures of chiralities. Detection of one enantimer at higher levels than another typically calls for enzymes.
http://msl-scicorner.jpl.nasa.gov/Instruments/SAM/