Class 8 Science - Chapter 12 Practice Test

Habitat: A place where an organism lives. It has biotic (living, e.g., plants, animals, microbes) and abiotic (non-living, e.g., air, water, soil, sunlight, temperature) components.
Population: A group of the same type of organisms living together in a habitat at a given time.
Community: Different populations of plants, animals, and microorganisms sharing the same habitat and interacting with each other.

Ecosystem: Formed by the interaction between biotic and abiotic components. Can be terrestrial (forest, farm) or aquatic (pond, river).
Producers (Autotrophs): Organisms like green plants that make their own food via photosynthesis.
Consumers (Heterotrophs): Organisms that depend on others for food. Includes herbivores (eat plants), carnivores (eat animals), and omnivores (eat both).
Decomposers (Saprotrophs): Fungi and bacteria that break down dead organic matter and recycle nutrients back into the soil.

Food Chain: A linear sequence showing 'who eats whom' in an ecosystem. Each organism occupies a specific position called a trophic level.
Food Web: A network of interconnected food chains, as organisms usually eat more than one type of food and are eaten by multiple predators.

Mutualism: Both organisms benefit (e.g., Honeybees and flowers).
Commensalism: One organism benefits, the other is unaffected (e.g., Orchids growing on tree branches).
Parasitism: One organism benefits, the other is harmed (e.g., Ticks feeding on dog's blood).

Overusing natural resources disrupts the balance. For example, excessive use of synthetic fertilizers and pesticides reduces soil fertility, decreases friendly microbes, and destroys organic matter (humus).
Protected areas (National Parks, Sanctuaries) help conserve endangered species and their habitats, like the mangrove forests of the Sundarbans.

🌿 Chapter 12 Revision Notes