Study Notes
Energy flow in biological systems begins with the Sun, which is the principal source of energy. Energy is transferred through ecosystems via food chains and food webs, starting with producers and moving through various trophic levels.
Exam Tips
Key Definitions to Remember
- Producer — an organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis.
- Consumer — an organism that gets its energy by feeding on other organisms.
- Herbivore — an animal that gets its energy by eating plants.
- Carnivore — an animal that gets its energy by eating other animals.
- Decomposer — an organism that gets its energy from dead or waste organic matter.
- Ecosystem — a unit containing all of the organisms and their environment, interacting together, in a given area.
- Trophic level — the position of an organism in a food chain or food web.
- Autotrophic nutrition — the mode of nutrition in which organisms make their food by themselves.
- Heterotrophic nutrition — the mode of nutrition where organisms depend on other organisms for food.
- Saprotrophic nutrition — involves organisms that depend on dead and decaying matter for their food.
Common Confusions
- Confusing producers with consumers.
- Misunderstanding the role of decomposers in nutrient cycling.
Typical Exam Questions
- What is the principal source of energy for biological systems? The Sun is the principal source of energy.
- How does energy flow through an ecosystem? Energy flows through an ecosystem via food chains and food webs, starting with producers.
- What role do decomposers play in an ecosystem? Decomposers break down dead organic matter, returning nutrients to the environment.
What Examiners Usually Test
- Understanding of energy flow from the Sun through ecosystems.
- Ability to identify and describe different trophic levels in a food chain.
- Knowledge of the roles of producers, consumers, and decomposers.