There are a variety of lymphocytes involved in the adaptive response, each with a specific function. One of the subsets of cells essential in the adaptive response is T helper cells. Choose the answer that most accurately describes the role of T helper cells in mounting the antibody response.

a. T helper cells present antigens to B cells, which is required for their activation.
b. T helper cells aid in the response by killing infected cells while the antibody response mounts.
c. T helper cells aid the antibody response by binding to the B cell MHCII/protein complex and secreting cytokines like IL-4.
d. T helper cells secrete IL-2, which is required for clonal expansion of B cells.

Suggest why placing wheels under a heavy box reduces the neccessary force required to push it along at a constant speed.

Which best describes this behavior? it is beneficial only to the males that do not fertilize eggs. it is beneficial only to the female workers that are not fertilized. it is beneficial to each one of the individual colony members. it is beneficial to the whole species, but not to all of the individual members.

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.