Study Notes
Interactions between living organisms involve food chains, food webs, and energy flow. These concepts explain how organisms are connected and how energy is transferred in an ecosystem.
- Food Chain — a linear sequence of organisms where nutrients and energy are transferred from one organism to another. Example: Grass → Rabbit → Fox
- Herbivore — an animal that gets its energy by eating plants. Example: Rabbit
- Carnivore — an animal that gets its energy by eating other animals. Example: Fox
- Decomposer — an organism that gets its energy from dead or waste organic matter. Example: Fungi
- Ecosystem — a unit containing all organisms and their environment, interacting together in a given area. Example: A lake
- Trophic Level — the position of an organism in a food chain or food web. Example: Primary consumer
- Food Web — a network of interlinked food chains showing the interactions between different organisms. Example: A web showing rabbits eaten by foxes and hawks
- Energy Flow — the transfer of energy through a food chain, with energy lost at each trophic level. Example: Energy lost as heat in mammals
- Pyramid of Numbers — a diagram showing the number of organisms at each trophic level in a food chain. Example: A pyramid with a large base of grass and a small top of hawks
Exam Tips
Key Definitions to Remember
- Food Chain: A linear sequence of organisms where nutrients and energy are transferred.
- Food Web: A network of interlinked food chains.
- Trophic Level: The position of an organism in a food chain or web.
Common Confusions
- Confusing food chains with food webs; remember, food webs are more complex and interconnected.
- Thinking pyramids of numbers must always be pyramid-shaped; they depend on organism size.
Typical Exam Questions
- What are the first organisms in a food chain? Producers
- What is the difference between a food chain and a food web? A food chain is linear, while a food web is interconnected.
- What role do humans play in a food chain? Humans can be primary, secondary, or tertiary consumers.
What Examiners Usually Test
- Understanding of energy flow and energy loss at each trophic level.
- Ability to differentiate between food chains and food webs.
- Knowledge of how to construct and interpret pyramids of numbers.