What Are Specialised Forms and Functions?
Every living thing — from the tiniest bacterium to the tallest tree — is made up of parts that work together. Whether we are looking at individual cells, groups of cells called tissues, or whole organisms living in challenging environments, one idea keeps coming up: form follows function. In other words, the shape and structure of a living thing is closely related to the job it has to do.
A feature (or change to a feature) that makes an organism better fitted to survive and thrive in its particular environment. Adaptations are inherited — passed from parent to offspring through genes.
Only heritable (inherited) traits count as adaptations. For example, a person developing a tan in summer is not an adaptation, but having naturally dark or light skin is an adaptation passed down through genes.
Over millions of years, living things have developed specialised forms — special structures, shapes, and behaviours — that allow them to carry out specific functions more efficiently. Being better adapted gives an organism a greater chance of survival and reproduction.
But how do these adaptations come about in the first place? Over many generations, individuals with features that help them survive are more likely to live long enough to reproduce and pass those features on to their offspring. Over time, the helpful features become more and more common in the population. This process is called natural selection — nature "selects" the individuals that are best suited to their environment.
The process by which individuals with features better suited to their environment are more likely to survive, reproduce, and pass those features on to the next generation. Over many generations, this leads to adaptations becoming widespread in a population.
In MYP Sciences, you will often explore two key ideas: Form (what something looks like or is made of) and Systems (how parts work together). This subtopic is all about how form and function are linked, and how living things operate as integrated systems.
Cells: The Building Blocks of Specialisation
The smallest unit of life is the cell. Each cell has a specific function — the task it carries out — and its structure (shape and internal organisation) is suited to that function.
The specific task that a cell carries out within an organism.
Motor nerve cell (neuron)
A motor neuron carries messages from the brain to a muscle. To do this efficiently, it has a long, narrow, cable-like nerve fibre. The message travels along this fibre quickly over a long distance — just like an electrical wire. Its elongated shape is perfectly matched to its function of long-distance communication.
Because there are many different jobs to perform inside an organism, there are many different cell types, each with a structure tailored to its role. This is why the cells in your muscles look completely different from the cells lining your gut or the cells in your skin.
Think of the different tools in a toolbox — a hammer, a screwdriver, and a pair of scissors all look very different because they each do a different job. Cells in your body are the same: different shapes for different tasks.
Plant cells have a cell wall on the outside of the cell membrane. Cell walls are made of a tough material and can withstand high pressures without bursting. They are also porous — water and dissolved substances can still pass through easily. This structure gives plant cells both strength and the ability to exchange materials with their surroundings.
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