KS3 · Biology

Common processes of all living organisms

A puppet leaps across a stage. A seed lies in the soil, doing nothing you can see. Which one is alive? Most people pick the puppet, and they're wrong.

Biology · Life processes

The puppet, the seed and the brick

Pick a thing, then pick a column. Go with your gut first. You'll see the reason whether you're right or wrong.

Is it living now, was it alive once, or has it never been alive at all?

Still to sort

Living (0)

Carries out the life processes at some stage of its life

Where the line is: Living or dead? A living thing still carries out the life processes. A dead thing did once, but has stopped.

Dead (was once alive) (0)

Was alive once, but no longer carries out any life processes

Where the line is: Dead or never alive? Ask whether it ever carried out the life processes. A dead thing did. A never-alive thing never did.

Never alive (0)

Was never made by reproduction and has never carried out the life processes

8 of 8 still to sort.

Sort them all, then switch to the second rule and look where the seed ends up. That one move is the whole lesson.

Watch out: Don't decide on movement alone. The puppet moves and has never been alive. The seed sits still and is alive.

The seven life processes, plus one word you need

Say what each one means before you reveal it. First letters, in order: M-R-S-G-R-E-N.

Biology · Life processes

So does moving mean alive?

A puppet dances across a stage on its strings. Water rushes down a stream. On a windowsill, a potted plant sits there, apparently doing nothing at all.

Which idea is closest to what you think right now?

If something moves, it's alive. The puppet and the water are both moving, so they count.Plants can't move, so movement isn't one of their life processes.If I can't see something moving, it can't be alive.Movement only counts when a living thing moves itself to achieve something, and plants do that too.

How sure are you?

I'm sureI think soI'm guessing

If something moves, it's alive. The puppet and the water are both moving, so they count.

This is a common misconception

Moving isn't enough. The puppet only moves because someone pulls the strings, and the water doesn't move itself either. Movement is a sign of life only when an organism moves itself to achieve something, such as getting food or water, or escaping a predator.

Plants can't move, so movement isn't one of their life processes.

This is a common misconception

Plants do move. They move parts of themselves, usually slowly. A Venus flytrap snaps shut to get nutrition. Some leaves curl up when they're touched, which protects the plant. And plants bend slowly towards sunlight, to get the light they need to make their own food.

If I can't see something moving, it can't be alive.

This is a common misconception

Microorganisms, such as bacteria, are far too small to see without a microscope. They are living organisms all the same, they carry out the same life processes, and they move too.

Movement only counts when a living thing moves itself to achieve something, and plants do that too.

This matches the evidence

Exactly right. The puppet and the water move, but not by themselves, so their movement tells you nothing about life. The plant on the windowsill is slowly bending towards the light so it can make food. That's movement with a purpose, even if it's too slow to watch.

Don't ask 'Is it moving?' Ask 'Is it moving ITSELF to achieve something?'

Biology · Life processes

Your turn: the mystery in the pond

A scientist looks at a drop of pond water under a microscope. They see a tiny thing swim towards a speck of food and take it in. Over the next few days it gets bigger. Then it splits to make two new ones just like itself. Is it living, dead or never alive? Explain your decision using the life processes. [4 marks]

Your answer

0 words · your answer stays on this page and is not sent anywhere.

The mark scheme

Decides that it is living. (1 mark)
Movement: it moves itself to achieve something (swimming towards food). (1 mark)
Nutrition or growth: it takes in food, or it gets bigger. (1 mark)
Reproduction: splitting to make new ones is reproduction, so new ones are made from a living thing. (1 mark)

Model answer

It is living. It moves itself to achieve something, because it swims towards food. It takes in food, which is nutrition, and it gets bigger, which is growth. When it splits to make two new ones, that is reproduction: the new ones are made from a living thing, just as every living organism is.

Don't stop at 'it moves'. Name the life processes you can see, then ask how it was made.

WHAT YOU'VE LEARNED

A quick recap of today's lesson.

Living, dead or never alive? Learn the two tests that sort anything in the world into the right group.

What you need to know

Everything on Earth is living, dead (was once alive) or never alive.
All living organisms, including animals, plants, fungi and microorganisms such as bacteria, carry out the same seven life processes: movement, reproduction, sensitivity, growth, respiration, excretion and nutrition.
Living organisms are made of cells, the basic unit of life.
Living things are made when other living things reproduce, and they die at the end of their life cycle. Something that has never been alive, like a brick, was not made by reproduction and has never carried out the life processes.
Movement only counts as a life process when an organism moves itself, or part of itself, to achieve something. Plants do this too, slowly.
Not every life process happens at every stage of a life cycle, but all of them happen at some stage.

The big picture

Everything is living, dead or never alive. Living things carry out seven life processes (MRS GREN) at some stage of their life cycle, and they are made when other living things reproduce. Movement only counts as a sign of life when an organism moves itself to achieve something.

Key points

1Three groups: living, dead, never alive.

2MRS GREN: Movement, Reproduction, Sensitivity, Growth, Respiration, Excretion, Nutrition.

3Two questions decide it: does it carry out the life processes at some stage of its life cycle, and was it made by reproduction?

4A puppet moves but isn't alive. A seed stays still but is alive.

.we-_R_18slubsnpfiv5ubrb_ [data-we-step]{display:flex !important}.we-_R_18slubsnpfiv5ubrb_ [data-we-solution]{display:block !important}.we-_R_18slubsnpfiv5ubrb_ [data-we-reveal]{display:none !important}

Worked example

Problem

A dog is fast asleep on the sofa. It hasn't moved for an hour. Is it living, dead or never alive?

⚠ Watch out

Thinking that anything moving must be alive, and anything still can't be. A puppet or flowing water moves without being alive, while a seed or a sleeping animal is alive while perfectly still. Check the life processes and how it was made, not just whether it moves.

🧠

Memory hook

MRS GREN: Movement, Reproduction, Sensitivity, Growth, Respiration, Excretion, Nutrition. Picture Mrs Gren the gardener holding a seed. It looks lifeless, but she knows it's quietly working through part of her list already.

✓

Check yourself

Without looking back, name all seven life processes. Then explain why a Venus flytrap is alive but a puppet on strings is not.

Flashcards

(14)

What three groups does everything on Earth fall into?

Living, dead (was once alive) and never alive.

What does MRS GREN stand for?

Movement, Reproduction, Sensitivity, Growth, Respiration, Excretion, Nutrition.

What is an organism?

Something that is living, or was once living but is now dead.

What is the basic unit that living organisms are made from?

The cell.

What is reproduction?

Making offspring: new living things.

What is sensitivity?

Sensing the surroundings and responding to them, for example a plant responding to light.

Growth means getting bigger. What else can it mean?

Repairing parts that have been damaged.

What is respiration?

Using food as a fuel to provide the energy an organism needs for all its processes.

What is excretion?

Getting rid of waste from chemical reactions, and of substances the organism doesn't need.

What is nutrition?

Using food or other nutrients, such as water, to stay alive.

When does movement count as a sign of life?

When an organism moves itself, or part of itself, to achieve something, such as getting food or escaping a predator.

Name two ways plants move.

Any two: a Venus flytrap closes its trap to catch food; some leaves curl up when touched; plants bend slowly towards sunlight.

Why is a brick 'never alive' rather than 'dead'?

It was never made by reproduction and has never carried out the life processes.

What is a life cycle?

The stages a living organism goes through during its life.

Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.

Learning with Lightbulb is opening soon

You can use this lesson now. Join the waitlist and we'll let you know when the full Lightbulb experience is ready.

Keep me posted

Common processes of all living organisms

The puppet, the seed and the brick

So does moving mean alive?

Is a seed really alive?

Your turn: the mystery in the pond

More KS3 Biology topics