Definitions [1]
Define a consumer.
A consumer is an organism that obtains energy by feeding on other organisms. As it cannot produce its own food, consumers rely on plants or other animals for nourishment, which are a vital part of the food chain. Consumers are further classified into primary consumers, secondary consumers, and tertiary consumers.
Key Points
Key Points: Ecosystem
- An ecosystem (a term coined by A.G. Tansley in 1935) is a self-sustaining unit where living (biotic) and non-living (abiotic) components continuously interact and exchange energy.
- It is structurally composed of abiotic factors (physical/chemical elements like sunlight, water, and soil) and biotic factors (all living organisms).
- The living organisms are divided by their roles into producers (synthesise food), consumers (feed on others), and decomposers (recycle nutrients from dead matter).
- Ecosystems are classified by their origin into natural (forests, oceans) or artificial/man-made (crop fields, aquariums) and by habitat into terrestrial or aquatic.
- Every ecosystem operates through four core functions: productivity (biomass generation), decomposition, a unidirectional energy flow, and continuous nutrient cycling.
Key Points: Structure and Function of an Ecosystem
- Two Structural Features → Species Composition (identifying species) + Spatial Pattern (distribution of biotic/abiotic components).
- Two Spatial Patterns → Stratification (vertical, e.g., trees→shrubs→herbs) + Zonation (horizontal, e.g., intertidal, littoral zones).
- Types → Terrestrial (forests, grasslands, deserts) + Aquatic (lakes, rivers, seas, oceans).
- Classification → Natural (self-sustainable) + Artificial (needs human input, e.g., farmland, fish tank).
- Components → Biotic (living) + Abiotic (non-living).
- 4 Functions → Productivity + Decomposition + Energy Flow + Nutrient Cycling (PDEN).
