Structures & Functions in Living Organisms
Living organisms have specializedstructuresthat perform specificfunctionsfor the organism.
Animal Structures
Animals have different structures that help them breathe, take in food and water, keep warm, protect themselves, and/or move from place to place.
· Breathing
Humans and many animals, like dogs, use their mouths to take air into lungs which they use for breathing.Other animals—like tadpoles, fish, and sharks—have long, thin holes called gills that help them get air out of the water they live in.Many insects take air in through tiny tubes in their bodies.
Dogs use lungs to breathe.Fish have gills near their side fins.
Insects take in air through tiny tubes.
· Taking in Food and Water
Almost all animals have mouths of some kind to take in food and water, but their mouths can have different shapes.Animals can also have other structures, such as hands or claws, that they use to pick up or capture food.
Some birds have beaks and/or sharp claws called talons that they use to capture or pick up food.Some birds can also suck liquid food from flowers using their beaks.Elephants have mouths, but they use their trunks to pick up their food.Many other kinds of animals have mouths with lips and teeth, and some animals, such as monkeys and humans, have hands to pick up their food.
Birds use their beaks to take in food.Elephants use their trunks to put food into their mouths.Monkeys have mouths with teeth and lips.
· Keeping Warm
Some animals, like seals, keep warm even in cold water because they have thick layers of fat under their skin.Water birds, like penguins, use fat and layers of fine feathers to keep the cold out.Fur can also help keep an animal from getting too cold.
Seals have thick layers of fat that keep them warm.Penguins use feathers to stay warm.Polar bears have thick fur coats.
· Protection
Porcupines have long, sharp quills that can stick in the skin of animals that try to hurt them.Turtles have hard shells into which they can pull their soft bodies.
Some fish, reptiles, and other animals have skin, fur, or scales that match the animals' surroundings.This helps the animal to stay safe by hiding from others.Cats can get away from other animals by using their claws to climb trees.
Porcupine quills can stick other animals.Turtle shells give turtles a safe place to hide.This hare has white fur, which makes it hard to see in the snow.
· Movement
Animals must move to find food, water, and space.They also must get away from other animals that try to hurt them.Some animals, like rats and people, have legs with feet and toes.Birds and butterflies have feet, but they mostly fly using wings.Fish don't have legs.They move using fins.
Many animals use legs and feet to move.Birds and some insects use wings to fly.Fish use fins to swim.
Plant Structures
Plants have different structures that help them take in water and nutrients from the ground, absorb light energy from the Sun, protect themselves, and reproduce.
The main structures of plants are the roots, stems, leaves, and flowers.The function of each is described below.
· Rootsanchor the plant in the soil, take in water from the soil, and take in nutrients from the soil.
· Leavestake in carbon dioxide from the air and absorb sunlight energy.Carbon dioxide and sunlight energy are needed for photosynthesis.Food is made in the plant's leaves through the process of photosynthesis.
· Stemsprovide structure for the plant and allow water and nutrients to travel throughout the plant.The stems of some plants can also help the plant to reproduce.If the stem is planted in the ground correctly, a new plant will grow.
· Flowersallow the plant to reproduce.They produce the carpel and the pollen.Once a flower is pollinated, the flowers can produce seeds and fruit.
· Seedsof a plant can grow into new plants once they get into the soil.This allows the plant to reproduce.
· Thefruitof a plant forms around the seeds.Fruit can have several purposes, including protecting the seeds, providing nutrients for the seeds, or tempting animals into eating the seeds so the seeds can be carried far away.This helps spread the growth of the particular plant species.
· Barkis a hard cover that protects the trunk of a tree from animals and from damage that may be caused by natural forces such as the wind.