environmental science

ecology.

CHAPTER 1: SCIENCE, SUSTAINABILITY, AND THE SCIENTIFIC METHOD

1. Scientific Method & Experiments

  • Independent Variable → The one thing you change.

  • Dependent Variable → What you measure.

  • Controlled Variables → Kept the same to ensure a fair test.

  • Hypothesis → A testable prediction. Format: If (independent variable change), then (dependent variable result).

  • Reading a Graph:

    • X-axis → Independent variable

    • Y-axis → Dependent variable

    • Look at trends, peaks, and patterns.

2. Ecological Footprint

  • Measures how much land and resources a person or population uses compared to Earth's capacity.

  • Higher consumption = Larger footprint.

3. Environmental Ethics

  • Anthropocentrism → Humans first, environment only matters if it benefits us.

  • Biocentrism → All living things have value.

  • Ecocentrism → The whole ecosystem (animals, plants, land) matters most.

4. Ecosystem Services (Nature’s "free" benefits to humans)

  • Provisioning: Food, water, raw materials.

  • Regulating: Climate control, air quality, pollination.

  • Supporting: Nutrient cycles, photosynthesis.

  • Cultural: Recreation, spiritual value.

CHAPTER 2: MATTER, ENERGY, AND ECOSYSTEMS

5. Biogeochemical Cycles

  • Hydrologic Cycle (Water Cycle) → Evaporation → Condensation → Precipitation → Runoff → Groundwater → Repeat.

  • Carbon Cycle → Plants absorb CO₂ → Animals eat plants → Respiration releases CO₂ → Decomposers break down dead matter → Fossil fuels burned = CO₂ released.

  • Nitrogen Cycle → Bacteria "fix" nitrogen into usable forms → Plants absorb it → Animals eat plants → Decomposition returns nitrogen to soil → Repeat.

  • Phosphorus Cycle → Rocks break down → Phosphates go into soil → Plants absorb them → Animals eat plants → Waste returns phosphorus to soil.

6. Photosynthesis & Cellular Respiration

  • Photosynthesis: Water+Carbon Dioxide+Sunlight→Glucose+Oxygen\text{Water} + \text{Carbon Dioxide} + \text{Sunlight} → \text{Glucose} + \text{Oxygen}Water+Carbon Dioxide+Sunlight→Glucose+Oxygen

  • Cellular Respiration: Glucose+Oxygen→Water+Carbon Dioxide+Energy (ATP)\text{Glucose} + \text{Oxygen} → \text{Water} + \text{Carbon Dioxide} + \text{Energy (ATP)}Glucose+Oxygen→Water+Carbon Dioxide+Energy (ATP)

  • Photosynthesis stores energy, respiration releases it!

CHAPTER 3: EVOLUTION, BIODIVERSITY, AND POPULATION ECOLOGY

7. Natural Selection

  • Survival of the fittest → Organisms with helpful traits survive & pass them on.

8. Evolution

  • Convergent Evolution → Different species develop similar traits due to environment (e.g., dolphins & sharks).

  • Divergent Evolution → One species splits into two over time.

9. Extinction

  • Species disappear when they can’t adapt to changes.

  • Mass extinctions → Large-scale die-offs (e.g., dinosaurs).

10. Phylogenetic Trees

  • Show evolutionary relationships → Who's related to whom based on common ancestors.

CHAPTER 4: SPECIES INTERACTIONS AND COMMUNITY ECOLOGY

11. Biomes

  • Different regions of the world classified by climate & organisms (e.g., rainforest, desert, tundra).

12. Food Webs

  • Producers (Autotrophs) → Make their own food (plants).

  • Consumers (Heterotrophs) → Eat other organisms.

    • Primary Consumers → Eat plants (herbivores).

    • Secondary Consumers → Eat primary consumers (carnivores).

    • Tertiary Consumers → Eat secondary consumers (top predators).

  • Keystone Species → A species that keeps the ecosystem balanced (e.g., wolves in Yellowstone).

13. Species Interactions

  • Resource Partitioning → Species divide resources to avoid competition.

  • Predator-Prey Relationships → One eats the other (e.g., lion & zebra).

  • Competition → Two species fight for resources.

  • Symbiosis (Living Together):

    • Mutualism (+/+) → Both benefit (e.g., bees & flowers).

    • Parasitism (+/-) → One benefits, one is harmed (e.g., fleas on dogs).

    • Commensalism (+/0) → One benefits, other unaffected (e.g., barnacles on whales).

14. Succession

  • Primary Succession → Starts from bare rock (e.g., after a volcano).

  • Secondary Succession → Rebuilding after a disturbance (e.g., after a wildfire).

CHAPTER 12: FRESHWATER, OCEANS, AND COASTS

15. Hydrologic Cycle (Water Cycle)

  • Same as before! Water moves through evaporation, condensation, precipitation, etc.

16. Aquifers

  • Underground water storage. Important for drinking water.

17. Dams (Pros & Cons)

  • Pros: Hydroelectric power, water storage, flood control.

  • Cons: Blocks fish migration, displaces people, changes ecosystems.

18. Wetlands

  • Filter water, prevent floods, support biodiversity.

19. Major Ocean Threats

  • Overfishing, pollution, acidification, coral bleaching, habitat destruction.

CHAPTER 6: HUMAN POPULATION

20. Age Structure Diagrams

  • Pyramid shape → Fast-growing population.

  • Rectangular shape → Stable population.

  • Inverted pyramid → Declining population.

21. Human Population Growth

  • Factors affecting growth: Birth rates, death rates, immigration, healthcare, education.

  • Carrying Capacity: The max population an environment can support.

22. Demographic Transition Model

  • Stage 1: High birth & death rates (low population growth).

  • Stage 2: Death rates drop (population rises).

  • Stage 3: Birth rates drop (population stabilizes).

  • Stage 4: Low birth & death rates (stable or declining population).