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# Quick check: the whole carbon cycle

Year 9 Earth and space · The carbon cycle

<!-- Speaker note: A self-test on the whole carbon cycle: flows between spheres, what drives each, and the effect of combustion (AC9S9U03, node 5, taught in class). About 10 minutes (About 10 min). -->

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## Today

**We are learning to** a few quick questions on labelling the carbon cycle, which flows are natural and which are human, and how burning fuels changed the balance. Taught in class; use this to check yourself.

- I can name the main carbon flows between spheres.
- I can sort flows as biological, geological or human-driven.
- I can explain how burning fossil fuels changed the balance.

<!-- Speaker note: Before class: A Quick check: a few questions on what students should know for AC9S9U03 node 5, which you teach in class. It has no board, no clip and no new teaching, and it is optional, so it never holds up course completion. Set the width with `?width=minimum`, `typical` (default) or `wider`. Use it as a self-test after your teaching, a starter, or revision. The four lessons on screen cover spheres, stores, living things and fossil fuels; this node is the student drawing or annotating the whole diagram. The questions check the vocabulary before or after. Teacher: Ask students to sketch the diagram first, then do the questions. Teacher: The sort is a good basis for colour-coding arrows on the diagram. -->

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## Why it matters

> Carbon has been moving between air, living things, water and rock for billions of years. What have we changed?

<!-- Speaker note: Your teacher covers drawing the whole cycle in class. These questions check the basics: the flows, who or what drives them, and the human change. -->

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## Between spheres

**Which flow moves carbon from the atmosphere into the biosphere?**

- Decomposition
- Photosynthesis
- Combustion
- Respiration

* Answer: Photosynthesis

<!-- Speaker note: Plants take carbon dioxide from the air and build it into sugars. Respiration, combustion and decomposition move carbon the other way. -->

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## Where from, where to

**Match each flow to where it moves carbon.**

| | |
|---|---|
| `Photosynthesis` | A. Geosphere to atmosphere |
| `Respiration by animals` | B. Atmosphere to hydrosphere |
| `Burning coal` | C. Atmosphere to biosphere |
| `The ocean dissolving carbon dioxide` | D. Biosphere to atmosphere |

* Answer: Photosynthesis → C. Atmosphere to biosphere; Respiration by animals → D. Biosphere to atmosphere; Burning coal → A. Geosphere to atmosphere; The ocean dissolving carbon dioxide → B. Atmosphere to hydrosphere

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## What drives the flow?

**Is the flow biological, geological or human-driven?**

Groups: Biological · Geological · Human-driven

Photosynthesis · Respiration · Decomposition · A volcano releasing carbon dioxide · Burning petrol in cars · Clearing and burning a forest

* Answer: Photosynthesis → Biological; Respiration → Biological; Decomposition → Biological; A volcano releasing carbon dioxide → Geological; Burning petrol in cars → Human-driven; Clearing and burning a forest → Human-driven

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## The human change

**Why has burning fossil fuels changed the carbon cycle's balance?**

- It moves carbon that was stored for millions of years into the air in a few centuries, faster than natural processes remove it
- It has no effect, because natural flows are much bigger
- It makes plants stop photosynthesising
- It destroys carbon

* Answer: It moves carbon that was stored for millions of years into the air in a few centuries, faster than natural processes remove it

<!-- Speaker note: The natural flows nearly balance each other. The extra flow from fossil fuels is not balanced, so carbon builds up in the air. -->

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## Exit ticket

**Name one biological, one geological and one human-driven carbon flow.**

* For example photosynthesis, a volcanic eruption, burning petrol.

<!-- Speaker note: Students answer on paper or a mini whiteboard before the reveal. Anyone who cannot answer needs the main idea again next lesson. Where this leads: Back in class: draw the full cycle with colour for biological, geological and human flows; link to Year 10 climate. -->