Ecosystems Revision Sheet

1. 📌 Essentials

• An ecosystem comprises biotic (living) and abiotic (non-living) components interacting within Earth's biosphere.
• Photosynthesis converts solar energy chemical energy; cellular respiration releases it.
• Food chains show linear energy transfer; food webs depict complex feeding relationships. Energy transfer efficiency between trophic levels is approximately 10%.
• Key biogeochemical cycles: water, carbon, nitrogen; human activities disrupt these cycles.
• Limiting factors (resources, predation, competition) regulate population sizes.
• Biodiversity (species richness) is vital for ecosystem stability; loss leads to extinction.
• Greenhouse gases (CO₂, CH₄, N₂O) trap heat, contributing to climate change.
• Earth's layers: core (hotter), mantle, crust; atomic number = protons.
• Earth's rotation (24h) causes day/night; revolution (365 days) causes seasons.
• Tides result from Moon's gravitational pull.

2. 🧩 Key Structures & Components