Hormone intro & HW assignment



Abscisic acid





Although we tend to look at plants as inanimate objects, we know they not only grow and reproduce with ease, but also respond to any environmental fluctuations occurring around them, including:

  • abiotic signals such as changes in temperature or light as well as to,
  • biotic presence's including pathogens, herbivores and competitors or more benign pollinators.

In some cases plants may alter their growth rate accordingly, either increasing or decreasing cell division and production of storage products. In other cases changes in light or temperature may indicate the wisdom of sexual reproduction and the investment of new tissue for flower and seed production. Shading may induce individuals to shoot up rapidly, while the force of wind may cause others to thicken their cell walls or add additional supportive cell layers.

Unlike animal systems where stimulated nerves moderate a cascade of appropriate responses, plants use hormones and associated biochemicals to both perceive and initiate appropriate reactions. Today in class, we'll go over specific effects of hormone action and next period review a few examples of how plants perceive the environment about them.