ACARA v9 CONTENT DESCRIPTION “analyse the relationship between structure and function of cells, tissues and organs in a plant and an animal organ system and explain how these systems enable survival of the individual”
Builds on the idea that living things are made of cells. Here those cells are gathered into larger and larger teams, until whole organs work together as a system that keeps a plant or an animal alive.
Living things are built in levels
A body is not one piece. Many cells of the same kind form a tissue, several tissues join to make an organ, and a group of organs working together makes an organ system. Each level is built from the level below, and the same ladder describes both a plant and an animal. Seeing these levels lets us ask a sharper question: how does the shape of each part suit its job?
The ladder of organisation
A body is built in levels. Step up the ladder from a single cell to a whole organ system.
Current level: Cell — the smallest living unit; one muscle cell or one leaf cell. Each level is made of many parts from the level below: cells build tissues, tissues build organs, and organs work together as a system. The same ladder describes a plant and an animal.
An animal organ system works as a team
The digestive system shows how organs cooperate. The mouth breaks food up, the stomach churns it, the small intestine passes nutrients into the blood, and the large intestine reclaims water. No single organ could do the whole job. Each one handles one stage in order, and only together do they keep the animal supplied with the energy it needs to live.
An animal organ system: digestion
The digestive system is a team of organs. Move the food along and read what each organ adds to the job.
Mouth: teeth break food up and saliva starts to soften it. No single organ could feed the body alone — each one does its part in order, so the food is broken down and its nutrients reach the blood. That is how the system keeps the whole animal supplied with energy.
A plant has organ systems too
A plant is organised the same way. Its roots, stem and leaves are organs that form a transport system. Roots absorb water and minerals from the soil, which rise through the stem to the leaves. The leaves use sunlight to make sugar, which travels back down to feed the rest of the plant. The same set of organs carries materials in both directions.
A plant organ system: transport
Roots, stem and leaves move materials around the plant. Switch the flow to follow each one.
Roots absorb water and minerals from the soil, and they rise up through the stem to the leaves. The roots, stem and leaves are different organs, but together they form one transport system that supplies the whole plant.
Structure fits function
At every level, the shape of a part suits the job it does. The walls of the alveoli in the lung are thin so gases cross quickly. Root hairs add surface so a plant can soak up more water. The small intestine is long and folded to absorb more nutrients, and the heart has thick muscle to push blood hard. Matching structure to function explains why a part looks the way it does.
Structure fits function
Pick a structure, then choose the job it is shaped to do. A green mark means the match is right.
You have matched 0 of 4 structures and 0 are correct. Each structure is shaped for its job: thin walls and folds and hairs all add surface or strength where the body needs it. Structure and function fit together at every level.
The system enables survival
An organ system matters because the whole individual depends on it. Each organ carries one essential task: the lungs take in oxygen, the heart moves blood, the stomach starts digestion. If one organ cannot do its task, that task is missing, and the individual struggles even though the other organs still work. Survival rests on the organs working together.
The whole system keeps the individual alive
Every organ carries one survival task. Impair one and see the consequence for the whole individual.
When every organ does its task, the individual stays healthy. Each organ in the system feeds the same body. Impair one to see why the whole working team is what keeps the individual alive.
Why this matters
Reading a body as nested levels, from cells to systems, lets us explain rather than just name its parts. We can see why a structure is shaped the way it is, how organs share a job, and why the health of the individual depends on the whole system working together. The same way of looking applies to a gum tree and to a kangaroo alike.
Quick self-check
1. What is the correct order, smallest to largest, in the ladder of organisation?
2. What is a tissue?
3. In a plant, which organs work together to carry water up and sugar down?
4. Why are the walls of the alveoli in the lungs very thin?
5. Why does impairing one organ in a system affect the whole individual?