Structure and function of living organisms
Living and non-living
Use the features of living beings to sort living from non-living, and follow a life cycle round from one stage to the next.
A snail's shell sits perfectly still on the sand, and it is part of a living animal. A car races down a road, and it is not living. So the quick test — does it move? — turns out to settle nothing on its own. The chapter builds a longer list instead, and asks you to check a thing against the whole of it.
The features of living beings
Living beings move, eat, grow, breathe, excrete, respond to stimuli, reproduce, and die. A car manages the first of those and none of the rest — it does not grow, does not eat, and cannot make another car. That is why the car goes in the non-living group however fast it travels.
Two words worth having
A stimulus is anything that prompts a living being to respond — a sound, a touch, a light going on. Plants do this as much as animals: the touch-me-not folds its leaves when you brush them. And excretion is the getting rid of waste: urine in animals, excess water given off by plants.
Have a play
Which way each part of this germinating seed grows.
Tap any part of the picture.
Worked example
Is a car living? It moves, it drinks fuel, and it needs air. Work it through against the list.
Grant what it does: it moves, and it takes in fuel and air.
Starting with the strongest case for 'living' is the honest way round. Three features look met at first glance.
Try it together
Now follow a mosquito from the water's surface to the air.
Four stages, and the creature looks completely different in each.
1.A mosquito's life begins as something laid in water, the same word used for a bird's beginning. What is that first stage called?
Have a go
Have a go on your own. Breathing is one part of a larger process. What is that process called?
Ready to practise?
Eight questions on what you have just read. Nothing is timed, and you can play as many times as you like.