Study Notes
Food chains show the transfer of energy from one organism to the next, starting with a producer, while food webs are networks of interconnected food chains. Trophic levels indicate the position of an organism in a food chain or web, and energy transfer between these levels is often inefficient, explaining why food chains usually have fewer than five trophic levels.
- 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 food web in a pond ecosystem
- Producer — an organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis Example: Grass
- Consumer — an organism that gets its energy by feeding on other organisms Example: Rabbit
- Herbivore — an animal that gets its energy by eating plants Example: Cow
- 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: shows the transfer of energy from one organism to the next, beginning with a producer
- Food web: a network of interconnected food chains
- Trophic level: the position of an organism in a food chain or food web
Common Confusions
- Confusing the shape of pyramids of numbers with pyramids of biomass
- Misunderstanding the inefficiency of energy transfer between trophic levels
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? Energy flows from producers to various levels of consumers and is lost at each level.
- Why are food chains usually fewer 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 and trophic levels
- Differences between pyramids of numbers and pyramids of biomass