Grade 9 Ontario Ecosystems Study Guide

Independent Variable

The specific variable that a scientist intentionally changes or manipulates in an experiment to test its effects.

Dependent Variable

The variable that is measured or observed to determine the effect resulting from the manipulation of the independent variable.

Controlled Variables

All factors that must be kept strictly identical across all test groups to ensure a fair test.

Control Group

The baseline test group that receives no special treatment and serves as a benchmark for comparison.

Experimental Group

The test group that receives the independent variable treatment being tested.

Qualitative Observation

A description of qualities or characteristics using the five senses without using numbers.

Quantitative Observation

An observation involving exact numerical measurements and standard units.

X-axis

The horizontal axis on a graph, where the independent variable is always plotted.

Y-axis

The vertical axis on a graph, where the dependent variable is always plotted.

DRY MIX Mnemonic

A memory tool for graphing: DRY stands for Dependent/Responding variable on the Y-axis; MIX stands for Manipulated/Independent variable on the X-axis.

Interpolation

The process of estimating a data value that falls inside the range of known graph points.

Extrapolation

The process of estimating a data value outside the range of known graph points by extending the trend line.

Biotic Factor

Any living or once-living part of an ecosystem.

Abiotic Factor

Any non-living physical or chemical component of an environment.

Organism

The smallest level of ecological organization, defined as a single living individual.

Population

A group of individuals belonging to the same species living in the same geographic area.

Community

All the different living species interacting within a specific area.

Ecosystem

A biological community combined with its non-living abiotic environment.

Biome

A large geographical region defined by its specific climate, vegetation, and wildlife.

Biosphere

The global sum of all Earth's ecosystems where life exists.

Atmosphere

The layer of gases surrounding the planet Earth.

Lithosphere

Earth's solid outer crust, including rocks and soil.

Hydrosphere

All liquid, frozen, and gaseous water on the planet.

Sustainable Ecosystem

An ecosystem that maintains its structure, processes, and biodiversity over time without depleting its resources.

Easter Island Case Study

A historical case study demonstrating total ecological collapse brought on by complete deforestation.

Traditional Ecological Knowledge (TEK)

Indigenous knowledge of local ecosystems accumulated across generations of environmental stewardship.

Seventh Generation Principle

An Indigenous philosophy dictating that decisions made today must protect and sustain the environment for seven generations into the future.

Natural Ecosystem

An ecosystem characterized by high biodiversity that is completely self-sustaining without human intervention.

Artificial Ecosystem

A human-made environment with low biodiversity that requires constant human inputs, such as watering and fertilizer.

Monoculture

An agricultural practice involving the cultivation of a single crop species over a large area.

Photosynthesis

A process that uses sunlight, water, and carbon dioxide to synthesize glucose and oxygen ($6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$).

Cellular Respiration

A process that breaks down glucose using oxygen to release stored energy, carbon dioxide, and water ($C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy}$).

Producer

Organisms at the base trophic level that synthesize their own food using sunlight.

Primary Consumer

Herbivores that consume producers directly.

Secondary Consumer

Carnivores or omnivores that consume primary consumers.

Tertiary Consumer

Top predators that consume secondary consumers.

Decomposer

Organisms that break down dead organic matter and recycle nutrients back into the soil.

Energy Transfer ($10\%$ Rule)

Exactly $10\%$ of stored energy is transferred from one trophic level up to the next.

Energy Loss in Food Chains

Approximately $90\%$ of energy is lost between trophic levels, primarily as heat and waste.

Food Web

A comprehensive diagram illustrating all interconnected food chains and energy pathways in an ecosystem.