On May 18, 1980, Mount St. Helens in Washington State experienced a huge volcanic eruption after a magnitude 5.1 earthquake. During the eruption, hot ash and pumice poured down the west, south, and east sides of the mountain, melting the snow and ice at the top of the volcano and producing volcanic mudflows. Which type of process first occurred in the ecosystem around Mount St. Helens after it erupted? primary succession
secondary succession
a climax community
species extinction

Female luna moths (actias luna) attract males by emitting chemical signals that spread through the air. a male hundreds of meters away can detect these molecules and fly toward their source. the sensory organs responsible for this behavior are the comblike antennae visible in the photograph shown here. each filament of an antenna is equipped with thousands of receptor cells that detect the sex attractant. based on what you learned in this chapter, propose a hypothesis to account for the ability of the male moth to detect a specific molecule in the presence of many other molecules in the air. what predictions does your hypothesis make? design an experiment to test one of these predictions.