T-helper cells have a molecule known as on their surface that enables them to respond to the targeted antigen. It is important to note that, in a reverse of the normal process, the Human Immunodeficiency Virus (HIV) attacks the T cells, which can then lead to an eventual compromise of the immune system against opportunistic infections.

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.

Animals that have thick fur and ae able to store large amounts of body fat live where ?

The scales shown in the introduction measure mass, or the amount of matter in a particular object. the scientific law of conservation of mass states that matter cannot be created or destroyed during a chemical reaction, but it can change from one form to another. did the simulation support this scientific law? explain why or why not.