Emergent Properties
Life exists in a hierarchical form, from single-celled bacteria to the entire biosphere, with all its ecosystems. At each higher level, organisms become more elaborate, and new properties appear. For example, evolutionary evidence indicates that complex eurkaryotes arose from simple prokaryotes.
The Cell
The cell is the basic unit for life. Whether an organism is prokaryote or eukaryote, its structure and function are based on the cell. The contents of cells may differ, but their importance is consistent.
Heritable Information
For life to continue, genetic instructions must be passed down from generation to generation. This heritable information is found in the DNA of all organisms, from bacteria to plants to people.
Structure and Function
At every step of the biological hierarchy, structure and function are connected. For example, different cells have specific components that help them carry out their duties. Red blood cells, which carry oxygen, are formed differently than the white blood cells that fight infection. The relationship between structure and function is also apparent in entire organisms and the physiological systems that serve them. A cat’s long, sensitive whiskers gather information from its environment.
Environmental Interactions
All organisms interact with their environment, which includes both organic and inorganic components. Material and energy flow back and forth. For instance, green plants use water, carbon dioxide and sunlight from their environment to produce their own energy through photosynthesis, but they release oxygen as a byproduct.
Feedback and Regulation
Living things have parts and processes that help individuals or species survive. Organisms use feedback to regulate the processes. This can be on a large scale. For example, births and deaths control animal populations in an ecosystem. Regulation also exists on the cellular level, such as a cell's ability to maintain a proper temperature.
Unity and Diversity
Great diversity exists among the three primary domains of living things: Bacteria, Archaea and Eukarya. Cell structure, nutritional requirements and environmental needs differ, but there are parallels, such as DNA. For example, scientists have found some genetic similarities between certain eukaryote cells and Archaea -- single-celled prokaryotes that live in extreme environments.
Evolution
Evolution is a unifying theme in biology. It explains changes in organisms over long periods of time. This includes adaptation, which allows life forms to acquire new characteristics in response to their environment through the process of natural selection. For example, deer mice in Nebraska’s Sand Hills are no longer brown. Over the course of 8,000 years, their coats lightened to facilitate hiding from predators.
Inquiry
Scientific inquiry is the process for acquiring new knowledge. Scientists make observations, form hypotheses, conduct experiments, draw conclusion and repeat the process.
Science, Technology and Society
Through science, humans learn about the natural world. Technology applies this knowledge in new ways. For instance, in 2013, Australian developers created a prototype for a bionic eye. It sends an image to a microchip in the brain, allowing the user to “see” the image.
