Life is greater than the sum of its parts.
Emergent properties describe the way new functions arise as smaller components combine to form more complex structures. Atoms form molecules, and organisms are made of cells. Each new level of organization is built on the one before it, bringing about new properties and processes.
Understanding emergent properties helps us conceptualize the relationship between physical structures and their function.
Atoms
- Atoms are the basic building blocks of matter, defined by their protons, neutrons, and electrons.
- Atoms react with one another to form bonds.
- Examples: Carbon, Oxygen, Hydrogen, Nitrogen.
- Draw Bohr models of Carbon, Hydrogen, and Oxygen.
Molecules
- As atoms react, they bond with specific arrangements to produce unique molecular structures.
- Depending on their structure, molecules can participate in different kinds of chemical reactions and interact with each other in different ways.
- Examples: Water, carbon dioxide, methane, ammonia.
- Draw a simplified structure of a nucleotide.
Biological Macromolecules
- Organic molecules (those containing C-H bonds) include a variety of biological molecules that link together to form large, complex molecules.
- These macromolecules serve a variety of metabolic and structural functions in organisms.
- Examples: Carbohydrates, proteins, lipids, and nucleic acids.
- Draw three nucleotides linked together.
Cellular Organelles
- Biological molecules are organized into a variety of specialized cellular structures.
- Organelles have specific, essential roles within the cell and are integrated to form more complex systems.
- Examples: Mitochondrion, chloroplast, nucleus, ribosome.
- Draw a diagram of a ribosome.
Cells
- Organelles interact within a structure bound together by a surface membrane.
- Single-celled organisms are themselves complete and independent, while other organisms are collections of cells working together to form even more complex structures. Cells possess all the characteristics of life. Anything made of cells is living; anything lacking cells is nonliving.
- Examples: Bacteria, algae, neurons, red blood cells.
- Draw a diagram of a plant cell, limited to its cell wall and its nucleus.
Tissues
- The cells of multicellular organisms are organized into tissues, collections of cells bound together into layers.
- The cells comprising a tissue perform a similar, coordinated function, and thus can perform tasks not possible by a single cell.
- Examples: Animal tissues: Nervous, muscle, epithelia, and connective. Plant tissues: Ground, vascular, and epidermal.
- Draw a diagram of a transverse section of a leaf (epidermis, mesophyll).
Organs
- Multiple complementary tissues are organized into large, complex organs. Multiple organs work together to form organ systems.
- Different organs perform a multitude of tasks required by the organism, such as circulating transport media (blood, sap), providing structural support, absorbing nutrients, and perceiving stimuli in the environment.
- Examples: Heart, eyes, leaves, roots.
- Draw a diagram of a leaf.
Multicellular Organisms
- The survival of multicellular organisms requires the coordination of multiple organ systems.
- Similar to their unicellular counterparts, multicellular organisms possess all the characteristics of life. The organisms represent the vast diversity of life we observe (unaided by a microscope) in the world around us.
- Examples: Humans, trees, dogs, fish.
- Draw a diagram of a small plant with two leaves and a yellow flower.
Populations
- When multiple organisms of the same kind interact, they form a population.
- They reproduce with one another to form new generations and may compete with one another over resources or cooperate to ensure their survival.
- Draw several small plants each with two leaves and a yellow flower.
Communities
- When multiple populations of different kinds of organisms interact, they form a community.
- Different populations might have predator-prey relationships, compete for resources, or exhibit forms of symbiosis.
- Draw several yellow flowers among flowers of different shapes and colors with bees and butterflies pollinating them.
Ecosystems
- Communities of organisms require resources that are ultimately derived from nonliving sources.
- An ecosystem describes the overall environment that emerges as a community interacts with the abiotic environment. This includes things like sunlight, water, minerals, and the atmosphere.
- Examples: Rainforest, desert, tundra, reef.
- Draw the same community as above, but include some rain clouds, the sun shining, and the soil.
Biosphere
All of Earth’s ecosystems exist in a unified, interconnected system referred to as the biosphere.
The atmosphere, oceans, forests, soils, and a variety of ecological components all have an impact on one another, despite the vast distances that may separate them. Winds might carry minerals from a desert to a rainforest on the other side of the planet. Ice melting at the poles can impact coastal ecosystems on the equator. Humidity produced from the ocean can create rain in an inland forest.
The entire planet is a collection of interacting parts; no single ecosystem exists in isolation.