Learning Objectives:

2.B.1:  Cell membranes are selectively permeable due to their structure.

2.C.1:  Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes.

2.D.4:      Plants and animals have a variety of chemical defenses against infections that affect dynamic homeostasis.

4.A.3:  Interactions between external stimuli and regulated gene expression result in specialization of cells, tissues, and organs.

4.A.6:  Interactions among living systems and with their environment result in the movement of matter and energy.