Ecology Notes

Ecology 🌱 Life on Earth & Habitats

• Habitat = place where an organism lives
  • Terrestrial (land)
  • Aquatic (water)
• Atmosphere
  • 78% nitrogen
  • 21% oxygen
  • Blocks harmful UV radiation
  • Regulates temperature
• Lithosphere
  • Rocks
  • Mountains
  • Ocean floor
• Hydrosphere
  • All water on earth (97% in oceans)
• Biosphere
  • Thin layer where life exists
  • Depends on resources

Ecosystem Basics 🌿

• Ecosystem: The biological environment of a given area.
• Living (biotic) + non-living (abiotic) parts in an area
• Biotic factors
  • Producers (plants)
  • Consumers (animals)
  • Decomposers (fungi, bacteria)
• Abiotic factors
  • Sunlight
  • Water
  • Temperature
  • Soil

Sustainability ♻

• Sustainable = natural cycles without interruption
• Artificial ecosystems need human help
• Described by
  • Species
  • Temperature
  • Water depth
  • Rainfall

Flow of Energy 🌞

• Sun = main energy source
• More energy → more biodiversity
• Food chain → simple, one path
• Food web → complex, shows many feeding links
• Energy pyramid → energy decreases at each level (broad base, narrow top)

Water Cycle 💧

1. Evaporation → water turns to vapor
2. Condensation → vapor cools into clouds
3. Precipitation → rain, snow falls
4. Transpiration → plants release water vapor
5. Runoff → water returns to oceans/lakes
   • Human impact → pollution, overuse, disrupts balance

Nitrogen Cycle 🌿

• Nitrogen gas (N_2) needs to be fixed → soil bacteria make ammonium & nitrate for plants
  • Aquatic: cyanobacteria does nitrogen fixing
  • Human impact → fertilizers, vehicle emissions, acid rain

Carbon Cycle 🌍

• Carbon moves between atmosphere, living things, soil, oceans
• Stored in fossil fuels, plants, oceans
• Released by respiration, decomposition, burning fossil fuels

Photosynthesis & Respiration 🌻

• Photosynthesis (plants) → sun + CO_2 + water → glucose + oxygen
• Cellular respiration (animals) → glucose + oxygen → ATP (energy) + CO_2 + water
• They complement each other!

Biodiversity 🌸

• Variety of species & genes in an ecosystem
• High biodiversity → more sustainable, resilient to stress
• Low biodiversity → less resilient, more vulnerable
• Threats → habitat loss, invasive species, pollution

Invasive Species ⚠

• Non-native, harm ecosystems, outcompete natives, spread fast, no predators

Key Takeaways to Memorize ✅

• Sun → base energy source
• Matter cycles → water, nitrogen, carbon
• Biodiversity = health & sustainability
• Human activities can disrupt balance