IBDP Biology Chapter 4 Notes
STUDY NOTES FOR BIOLOGY CHAPTER 4 – ECOLOGY
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This unit links up the topics of the ecosystem, energy-flow, carbon cycling and climate change. Habitat is the natural living environment of an organism, and species is a group of organisms that can interbreed and produce fertile offspring (hybrids are infertile). We first talk about the levels of ecological organisation (individual > population > community > ecosystem > biome > biosphere), followed by decomposers ( organisms that breakdown organic waste into inorganic constituents). Then we examine the energy flow through the food chain and food web. Every level in a food chain is called a trophic level; producers, i.e. green plants, always occupy the first trophic level.
There are generally 3 to 4 trophic levels, but they may go up to 5 sometimes. Interlinked food chains form a food web. Only 10% of the energy and biomass gets transferred from one trophic level to another, and the rest 90% is lost as heat which contributes to global warming. This pattern of energy distribution is often referred to as the pyramid of energy. Next, we dive into the carbon cycle, Where producers take up the CO₂ and convert it into glucose. Methanogens produce methane as a waste. CO₂ is released when fossil fuels are burnt in air. At the end we focus on global warming due to increased greenhouse effect wherein the atmosphere retains its heat even when no sunlight is hitting the surface. This trapping of heat is due to greenhouse gases like water vapor, CO₂, methane and nitrous oxide NO₂.
- Chapter 1 Cell
- Chapter 2 Molecular Biology
- Chapter 3 Genetics
- Chapter 4 Ecology
- Chapter 5 Evolution and biodiversity
- Chapter 6 Human Physiology
- Chapter 7 Nucleic Acids
- Chapter 8 Metabolism, cell respiration and photosynthesis
- Chapter 9 Plant Biology
- Chapter 10 Genetics and evolution
- Chapter 11 Animal Physiology
- Chapter 12 Biotechnology and bioinformatics
- Chapter 13 Neurobiology and behaviour
- Chapter 14 Ecology and conservation
- Chapter 15 Human Physiology