Functions of Living Things

• Living things perform functions to stay alive.
• These functions are performed in different ways by different organisms

Common Functions of living things

• Movement
• Growth
• Feeding
• Breathing
• Feeling
• Reproduction
• Waste elimination

Recall

• Earth has billions of living creatures which depend on each other
• They can survive here because of the presence of water, minerals, light, air, and warmth

Movement

• Most animals move their whole body
• Plants can only move certain parts like leaves which turn to face the sun
• Animals move to find food, water, mate, or avoid danger
• Movement is called locomotion and uses energy
• Mimosa leaves close when touched
• Insects flap wings to move
• Jellyfish squeeze water to move
• Fish use their head, body, and tail to push water
• Snakes move forward by making loops
• Leeches contract muscles
• Hummingbirds hover while feeding due to their lightweight skeleton and forelimbs modified into wings
• Barnacles fix themselves in one place

Growth

• Young plants and animals are smaller than adults
• A small seed can grow into a tall tree
• Young snake grows from finger size to over two meters
• Living things grow until they become adults
• Some species grow faster than others
• Human babies take over 20 years to reach full size
• Tigers take a few years, and bean plants take a few weeks
• Ears and nose continue to grow throughout life at an average of 0.22mm per year

Food

• Animals take in food in different ways
• Fish swallow their food whole or in lumps
• Herbivores chew their food
• Mosquitoes use a needle-like mouthpart to suck blood
• Plants with green leaves make their own food through photosynthesis, using water, carbon dioxide, and sunlight
• Not all plants make their own food
• Venus flytraps trap insects, break them down, and absorb them
• Rafflesia is a parasite and lives off the food made by other plants

Questions to ask about plants and animals

• Why does it need food?
• What kind of food does it need?
• Where and how does it get food?
• How and when does it take in food?

Respiration

• Living things need oxygen to survive
• Earth is surrounded by the atmosphere, which contains different gases
• There is no air on the moon
• Inhaling and exhaling is called respiration
• Mammals, birds, and reptiles breathe through the nose or nostrils into lungs
• Oxygen is absorbed by the blood and carried to all parts of the body
• Carbon dioxide is exhaled
• Insects breathe through spiracles on the sides of their bodies
• Oxygen enters through the spiracles and is pushed through air-tubes
• Water contains dissolved gases
• Fish, prawns, crabs, and tadpoles breathe through gills
• They gulp water, and oxygen is absorbed in the gills after which the water is expelled
• Plants breathe through tiny holes called stomata in the leaves allowing air and water to pass through
• Amoebas, earthworms, and frogs breathe through their moist body surface when in water

Waste

• Living things take in food and air
• The body does not need all of this and what is not needed is expelled as waste
• Waste can be solid, fluid, or gas
• Humans exhale carbon dioxide as waste air
• Plants store unneeded food for energy in leaves, roots, stem, and other parts
• These are shed every year

Sensitivity

• Animals have senses like humans: nose to smell, eyes to see, ears to hear, tongue to taste, and skin to feel
• Some creatures have special body parts for sensing
• Insects have feelers or antennae
• Flies taste with their feet
• Spiders have hairy legs to detect movement in their webs
• Snakes use their tongues to pick up chemical particles and an organ in their head reacts to scents
• Zebras use senses to detect predators
• Bats have sharp ears and use high-pitched sounds to locate objects
• Fish have a lateral line to feel vibrations in the water

Reproduction

• Most mammals give birth to babies e.g. humans, cows, giraffes
• Some mammals produce one baby at a time, while others produce several
• Mice can produce up to 32 babies at one time
• Birds, reptiles, and insects lay eggs
• Plants produce seeds or spores which develop into new plants
• Babies grow to look like their parents

Key words

Respiration

• The act of breathing air in and out

Locomotion

• Movement or the power to move from one place to another

Spiracle

• Small openings on insects that lead to the respiratory system

Spore

• A small, usually one-celled reproductive structure produced by seedless plants, fungi

Predator

• A carnivorous animal that hunts other animals to eat