In pea plants, there are two alleles for the gene controlling Flower Color, with the allele for Purple Flowers (P) being completely-dominant to the allele for White Flowers (p). Another gene controls Flower Position with the allele for Axial Flowers (A) being completely-dominant to the allele for Terminal Flowers (a). If a plant that was true-breeding for Purple-Axial Flowers was crossed with a plant that true-breeding for White-Terminal Flowers, what would be the expected phenotypic ratio two generations later

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.