Big Idea 2 – Biological systems utilize free energy and molecular building blocks to grow, to reproduce and to maintain dynamic homeostasis. EU 2A – Growth, reproduction, and maintenance of the organization of living systems require free energy and matter. 1. All living systems require a constant input of free energy. 2. Organisms capture and store free energy for use in biological processes. 3. Organisms must exchange matter with the environment to grow, reproduce, and maintain organization.EU 2B – Growth, reproduction and dynamic homeostasis require that cells create and maintain internal environments that are different from their external environment. 1. Cell membranes are selectively permeable due to their structure. 2. Growth and dynamic homeostasis are maintained by the constant movement of molecules across membranes. 3. Eukaryotic cells maintain internal membranes that partition the cell into specialized regions.EU 2C – organisms use feedback mechanisms to regulate growth and reproduction, and to maintain dynamic homeostasis. 1. Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. 2. Organisms respond to changes in their external environments.EU 2D – Growth and dynamic homeostasis of a biological system are influenced by changes in the system’s environment. 1. All biological systems from cells and organisms to populations, communities and ecosystems are affected by complex biotic and abiotic interactions involving exchange of matter and free energy. 2. Homeostatic mechanisms reflect both common ancestry and divergence due to adaptation in different environments. 3. Biological systems are affected by disruptions to their dynamic homeostasis. 4. Plants and animals have a variety of chemical defenses against infections that affect dynamic homeostasis.EU 2E – Many biological processes involved in growth, reproduction and dynamic homeostasis include temporal regulation and coordination. 1. Timing and coordination of specific events are necessary for the normal development of an organism, and these events are regulated by a variety of mechanisms. 2. Timing and coordination of physiological events are regulated by multiple mechanisms. 3. Timing and coordination of behavior are regulated by various mechanisms and are important in natural selection.