Living and Non-living

What you'll learn

Feature	Living things	Non-living things
Growth	Yes — increase in size	No (though some non-living things change shape)
Respiration	Yes — release energy from food	No
Movement	Yes — part or whole body	Usually no (exceptions: wind, water)
Sensitivity/Response	Yes — respond to stimuli	No
Nutrition	Yes — take in food	No
Excretion	Yes — remove waste	No
Reproduction	Yes — produce offspring	No
Life span	Have a definite life span (birth→death)	No biological life span

MRS GREN mnemonic for life processes: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition.

Difficult cases:

Viruses: have genetic material and reproduce, but cannot carry out independent life processes → considered on the border of living and non-living.
Seeds and spores: appear non-living (dormant) but are alive — they can germinate.
Fire: moves, uses oxygen, grows → but NOT living (no cells, no reproduction, no growth via cell division).

Nutrition: all living things need food to get energy. Plants make their own (autotrophs/photosynthesis); animals eat other organisms (heterotrophs).
Respiration: breaking down food (glucose) to release energy. All cells respire. Not the same as breathing.
Movement: plants move slowly (tropisms — roots grow toward water, stems toward light); animals move much faster.
Growth: irreversible increase in size via cell division and cell enlargement.
Reproduction: produce offspring of the same kind — ensures species continuity. Can be sexual (two parents) or asexual (one parent).
Response to stimuli: react to changes in environment (touch, light, temperature, chemicals).
Excretion: remove metabolic waste products. Plants release O₂ from photosynthesis and CO₂ from respiration; animals produce urine, CO₂, sweat.

Habitat: the natural environment where an organism lives, providing food, water, shelter and suitable conditions.

Major habitats and their organisms:

Habitat	Conditions	Example organisms
Tropical rainforest	Hot, wet, humid, dense vegetation	Gorilla, jaguar, parrot, orchids
Desert	Hot/cold, dry, little water	Camel, scorpion, cactus, sand fox
Grassland/Savanna	Seasonal rain, open grassland	Elephant, zebra, lion, grass
Ocean	Saltwater, sunlight only in upper layers	Whale, shark, coral, seaweed
Freshwater	Rivers, lakes, ponds	Fish, frog, water lily, dragonfly
Polar (Arctic/Antarctic)	Extremely cold, ice	Polar bear, penguin, seal, Arctic fox
Mountains	Cold, thin air, steep	Snow leopard, yak, rhododendron

Adaptation: inherited features (structural, physiological or behavioural) that help an organism survive and reproduce in its specific habitat.

Desert adaptations:

Camel: stores fat in hump (energy); can drink large amounts at once; nostrils can close; long eyelashes; wide feet to walk on sand.
Cactus: thick fleshy stems store water; leaves reduced to spines (reduce water loss); deep/wide roots; waxy surface (cuticle) prevents evaporation.
Sand fox: large ears radiate heat and hear prey; light coat matches sand; active at night.

Aquatic (water) adaptations:

Fish: streamlined body; fins for propulsion and balance; gills to extract dissolved oxygen from water; scales for protection; swim bladder for buoyancy.
Duck: webbed feet for swimming; waterproof feathers (oil gland); flat bill to filter water for food.
Lotus: roots in mud; long stalk reaches surface; flat floating leaves; stomata on top of leaf.

Cold/polar adaptations:

Polar bear: thick fur (two layers) traps air for insulation; thick fat layer (blubber); white fur for camouflage in snow; large paws for grip on ice.
Penguin: flippers (modified wings) for swimming; waterproof feathers; huddle together for warmth; counter-current heat exchange in flippers.

Behavioural adaptations:

Hibernation (bears, bats) — sleep through winter to conserve energy when food is scarce.
Migration (birds, whales) — move seasonally to find food, better climate or breeding grounds.
Nocturnal activity (owls, bats) — active at night to avoid heat or to hunt when prey is active.

List five characteristics shared by all living things.
Why is fire not considered a living thing even though it shows some characteristics of life?
Define habitat. Give two organisms from the desert habitat and their adaptations.
How is a cactus adapted to survive in the desert?
How does a polar bear survive in the Arctic?

Open the Practice tab for graded questions on Living and Non-living.