Plant Hormones

Auxins:
Auxins are a class of plant hormone that stimulate cell elongation. Auxins are growth hormones that make the dark sides of plants grow so the plant moves toward its light source. They also are responsible for: cell division, differentiation between xylem and phloem, fruit abscission, setting, growth, and ripening, and flower growth. It also plays a part in the labs were are currently doing (phototropism and gravitropism) because it controls which way plants grow.
In response to: light source
AUXIN=GROWTH

(this information from here and here)

Abscisic Acid:
Abscisic acid, or ABA, helps plants react and adapt to stressors like temperature. ABA is responsible for keeping the plant alive by keeping cells hydrated, stimulating root growth, regulating bud growth, seed maturation, and fruit abscission (which is what the hormone was named for). ABA basically exists to inhibit growth and make sure the plant can survive whatever harmful conditions its in.
In response to: environmental factors
ABA=STRESS REACTION

(this information from here)

Ethylene
Ethylene is produced by mature fruits and makes them ripen.  Ethylene controls the abscission of fruits, drooping of leaves, and seed germination, as well as some different functions in various plants (such as stem elongation in rice).
In response to: fruit maturation
ETHYLENE=FRUIT

(this information from here)