Essential Knowledge 2.D.2

Homeostatic mechanisms reflect both common ancestry and divergence due to adaptation in different environments.

Continuity of homeostatic mechanisms reflects common ancestry, while changes may occur in response to different environmental conditions.

Organisms have various mechanisms for obtaining nutrients and eliminating wastes.

Examples:

• gas exchange in aquatic and terrestrial plants
• digestive mechanisms in animals such as food vacuoles, gastrovascular cavities, one-way digestive systems
• respiratory systems of aquatic and terrestrial animals
• nitrogenous waste production and elimination in aquatic and terrestrial animals.

Homeostatic control systems in species of microbes, plants and animals support common ancestry.

Examples:

• excretory systems in flatworms, earthworms and vertebrates
• osmoregulation in bacteria, fish and protists
• osmoregulation in aquatic and terrestrial plants
• circulatory systems in fish, amphibians and mammals
• thermoregulation in aquatic and terrestrial animals (countercurrent exchange mechanisms)

Students should be able to:

LO 2.25 Construct explanations based on scientific evidence that homeostatic mechanisms reflect continuity due to common ancestry and/or divergence due to adaptation in different environments.

LO 2.26 Analyze data to identify phylogenetic patterns or relationships, showing that homeostatic mechanisms reflect both continuity due to common ancestry and change due to evolution in different environments.

LO 2.27 Connect differences in the environment with the evolution of homeostatic mechanisms.