Study Notes
Food chains and food webs illustrate the transfer of energy through ecosystems, starting with producers and moving through various consumers. They demonstrate the interdependence of organisms within an ecosystem.
- Food chain — shows the transfer of energy from one organism to the next, beginning with a producer.
Example: Grass → Grasshopper → Frog → Snake → Hawk - Food web — a network of interconnected food chains.
Example: A diagram showing multiple overlapping food chains in a forest ecosystem. - Producer — an organism that makes its own organic nutrients, usually using energy from sunlight through photosynthesis.
Example: Plants - Consumer — an organism that gets its energy by feeding on other organisms.
Example: Animals - Herbivore — an animal that gets its energy by eating plants.
Example: Deer - Carnivore — an animal that gets its energy by eating other animals.
Example: Lion - Decomposer — an organism that gets its energy from dead or waste organic matter.
Example: Fungi - Ecosystem — a unit containing all of the 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
Exam Tips
Key Definitions to Remember
- Food chain
- Food web
- Producer
- Consumer
- Herbivore
- Carnivore
- Decomposer
- Ecosystem
- Trophic level
Common Confusions
- Confusing food chains with food webs
- Misunderstanding the role of decomposers
- Thinking pyramids of numbers must always be pyramid-shaped
Typical Exam Questions
- What is a food chain?
A series of organisms each dependent on the next as a source of food. - How does energy transfer in a food web?
Through interconnected food chains where energy flows from producers to various levels of consumers. - Why are food chains usually less than five trophic levels?
Due to energy loss at each level, making it inefficient to support more levels.
What Examiners Usually Test
- Ability to construct and interpret food chains and food webs
- Understanding of energy transfer between trophic levels
- Knowledge of the roles of producers, consumers, and decomposers
- Differences between pyramids of numbers and pyramids of biomass