ess 2.1

Biosphere

An ecological system composed of individuals, populations, communities, and ecosystems.

Individual Organism

A single member of a specific species.

Classification of Organisms

A systematic arrangement that allows for the efficient identification of organisms and the prediction of their characteristics.

Taxonomists

Scientists who use a variety of tools (such as morphology, DNA analysis, and keys) to identify and classify an organism.

Population

A group of organisms of the same species living in the same area at the same time, and which are capable of interbreeding to produce fertile offspring.

Population Distribution Factors

Variables that determine where a population is located; these can be abiotic (non-living physical/chemical) or biotic (living/biological).

Abiotic Factors (Examples)

Temperature, sunlight, pH, salinity, dissolved oxygen, and soil texture that affect species distributions in ecosystems.

Niche

The particular set of abiotic and biotic conditions and resources upon which an organism or a population depends to survive and reproduce.

Population Interactions

The ways populations interact in ecosystems, including herbivory, predation, parasitism, mutualism, disease, and competition, which lead to ecological, behavioural, and evolutionary consequences.

Carrying Capacity

The maximum size of a population that a specific environment can sustainably support, determined by competition for limited resources.

Population Size Regulation

The control of population numbers driven by density-dependent factors (e.g., disease, competition) and negative feedback mechanisms that return the population to equilibrium.

Population Growth Patterns

Can either be exponential (rapid, unrestricted growth in an ideal environment) or limited by carrying capacity (logistic growth slowing down as resources become scarce).

Limiting Factors on Human Populations

Historically constrained human growth, but have increasingly been eliminated (via technology, medicine, agriculture), resulting in severe consequences for the sustainability of global ecosystems.

Human Carrying Capacity

Cannot be easily assessed because humans can alter their environment, substitute resources, develop new technologies, and import goods from other regions.

Estimating Population Abundance

Methods used to determine population size, including random sampling (for uniform habitats), systematic sampling (at regular intervals), or transect sampling (along an environmental gradient).

Random Quadrat Sampling

A method specifically used to estimate population size and density for non-mobile (sessile) organisms like plants or slow-moving animals.

Capture–Mark–Release–Recapture & Lincoln Index

An ecological method and mathematical formula used to estimate the population size for mobile organisms.

Community

A collection of multiple interacting populations of different species living and interacting within the same ecosystem.

Habitat

The specific physical location or environment in which a community, species, population, or organism naturally lives.

Ecosystems as Open Systems

Systems in which both energy (e.g., sunlight entering, heat leaving) and matter (e.g., nutrients, water) can enter and exit across their boundaries.

Sustainability in Ecosystems

A natural property of healthy ecosystems allowing them to maintain their structure, functions, and biodiversity over long periods without depletion.

Tipping Points

Critical thresholds in ecosystem stability that, when crossed due to human activity, lead to rapid, often irreversible shifts to a new ecological state.

Keystone Species

Species that have a disproportionately large and critical role in maintaining the structure and overall sustainability of their ecosystems.

Planetary Boundaries Model

A framework indicating that human-induced changes to biosphere integrity (biodiversity loss and ecological disruption) have passed a critical safety threshold.

Reversing Loss of Biosphere Integrity

The urgent need to restore biodiversity and ecological functions to avoid passing critical tipping points that could permanently destabilize Earth systems.

Clade Classification Advantages (HL)

Using a classification method based on clades (groups sharing a common ancestor) illustrates actual evolutionary relationships rather than just physical similarities.

Traditional Taxonomy Difficulties (HL)

Classifying organisms into the traditional hierarchy of taxa (Kingdom, Phylum, Class, etc.) can be rigid and often fails to accurately reflect complex evolutionary histories or genetic evidence.

Fundamental vs. Realized Niche (HL)

The fundamental niche is the full range of conditions a species could theoretically occupy; the realized niche is the actual, narrower conditions it occupies due to biotic interactions like competition.

Life Cycle Variations (HL)

Differences between species regarding their reproductive behaviour (e.g., r-strategists vs. K-strategists, mating rituals) and overall lifespan.

Importance of Species Knowledge (HL)

Understanding an organism's classifications, specific niche requirements, and life cycles is essential to accurately grasp and mitigate the extent of human impacts upon them.

Ethics (HL)

The branch of philosophy that focuses on moral principles, evaluating what behaviours are considered right and wrong.

Environmental Ethics (HL)

A specific branch of ethical philosophy that addresses environmental issues and the moral relationship between humans and the natural world.

Ethical Frameworks & Conflicting Values (HL)

A variety of ethical perspectives that emerge from differing fundamental beliefs concerning the exact relationship between humans and nature.

Instrumental Value (HL)

The usefulness, utility, or economic benefit an entity has for humans (e.g., a forest valued for its timber or carbon sequestration).

Intrinsic Value (HL)

The inherent worth or value one may attach to something simply for what it is in itself, entirely independent of its usefulness to humans.

Value Inclusivity (HL)

The principle that the concepts of instrumental and intrinsic value are not exclusive; a single entity (like a river) can be valued for both its utility and its inherent existence.

Moral Standing (HL)

A status assigned to an entity indicating that it must be morally considered with regard to how we ought to act towards it.

Major Approaches to Traditional Ethics (HL)

The three primary frameworks: virtue ethics, consequentialist (e.g., utilitarian) ethics, and rights-based (deontological) ethics.

Virtue Ethics (HL)

An ethical approach focusing on the character of the person performing the action; it assumes that good, virtuous people will naturally do good actions and bad people will do bad actions.

Consequentialist Ethics (HL)

The ethical view that the outcomes, results, or consequences of an action are what ultimately determine the morality of that action (e.g., Utilitarianism seeks the greatest good for the greatest number).

Rights-based (Deontological) Ethics (HL)

An ethical system focusing on the actions themselves and whether they conflict with the rights of others, though debate continues regarding exactly what these rights might be (e.g., the right to clean air or animal rights).

Economics (HL)

The study of how humans produce, distribute, and consume goods and services, analyzing behavior both individually and collectively.

Environmental Economics (HL)

A sub-field of economics applied specifically to the environment and the management/resolution of environmental issues.

Market Failure (HL)

An economic situation that occurs when the free market's allocation of goods and services imposes negative externalities or detrimental impacts on the environment (e.g., industrial pollution without financial penalty).

Polluter-Pays Principle (HL)

An economic and legal strategy applied when the market fails to prevent negative impacts, mandating that the party responsible for producing pollution must pay the costs of managing it to prevent damage to human health or the environment.