Breeding pairs of magnolia warblers build nests out of pieces of grass and twigs. The female warbler will then lay her eggs in the nest and sit on the eggs for a few weeks until they hatch. After the offspring have hatched, the female will continue to sit on the newborn chicks to keep them warm. Both the male and the female bring food for the offspring to eat until the young are mature enough to find food on their own.

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.