Chapter 2.2, 2.3 2.4 & 2.5

Topic 2.2: Communities and Ecosystems

• Species – A group of organisms that can interbreed and produce fertile offspring.

• Population – A group of individuals of the same species living in a specific area.

• Community – All the populations of different species living and interacting in an area.

• Ecosystem – A community of organisms and their interactions with the abiotic environment.

• Habitat – The natural environment in which a species lives.

• Niche – The role and position of a species within an ecosystem.

• Predation – One organism (predator) hunts and eats another (prey).

• Herbivory – An animal feeds on plant material.

• Parasitism – One organism benefits, the other is harmed (e.g., tapeworms).

• Mutualism – Both species benefit (e.g., bees and flowers).

• Competition – Organisms compete for limited resources.

• Carrying Capacity (K) – The maximum number of individuals an environment can support.

• S-Curve – Logistic population growth where growth slows at carrying capacity.

• J-Curve – Exponential population growth that can lead to a crash.

• Density-Dependent Factors – Factors affected by population size (e.g., disease, competition).

• Density-Independent Factors – Factors unaffected by population size (e.g., natural disasters).

• Limiting Factor – A resource that restricts population growth.

Topic 2.3: Flows of Energy and Matter

• Photosynthesis – Process where plants convert sunlight into chemical energy.

• Respiration – Breakdown of glucose to release energy.

• Producer (Autotroph) – Organism that makes its own food (e.g., plants).

• Consumer (Heterotroph) – Organism that eats others for energy.

• Decomposer – Breaks down dead organisms (e.g., fungi, bacteria).

• Food Chain – A linear flow of energy through trophic levels.

• Food Web – Interconnected food chains in an ecosystem.

• Trophic Level – A feeding level in a food chain.

• Gross Primary Productivity (GPP) – Total energy produced by plants.

• Net Primary Productivity (NPP) – Energy available to consumers after plant respiration (NPP = GPP - R).

• Ecological Pyramids – Diagrams that show energy, biomass, or numbers at trophic levels.

• Bioaccumulation – The buildup of toxins in an organism.

• Biomagnification – The increase of toxin concentration as you move up trophic levels.

• Maximum Sustainable Yield (MSY) – The highest rate of use that allows a resource to replenish.

Topic 2.4: Biogeochemical Cycles

• Biogeochemical Cycle – Movement of nutrients through biotic and abiotic factors.

• Carbon Cycle – The circulation of carbon through the biosphere, atmosphere, and oceans.

• Carbon Source – Releases carbon (e.g., burning fossil fuels).

• Carbon Sink – Absorbs and stores carbon (e.g., forests, oceans).

• Nitrogen Cycle – The movement of nitrogen through ecosystems.

• Fixation – Process where bacteria convert nitrogen gas into usable forms.

• Denitrification – Bacteria convert nitrates back into nitrogen gas.

• Phosphorus Cycle – Movement of phosphorus through rocks, water, and living things.

• Decomposition – Breakdown of organic matter, returning nutrients to the soil.

Topic 2.5: Investigating Ecosystems

• Zonation – Change in species distribution across an environmental gradient (e.g., altitude).

• Succession – Natural process of ecosystem development over time.

• Primary Succession – Occurs on newly formed land (e.g., volcanic island).

• Secondary Succession – Occurs after disturbance (e.g., forest fire).

• Plagioclimax – A stable community maintained by human activity.

• Climax Community – The final, stable stage of succession.

• Quadrat Sampling – A method to estimate population size.

• Transect – A line used to measure changes in species along an environmental gradient.

• Biotic Index – A measure of environmental health using indicator species.