Education Always

Level: JHS, Basic 8  |  Subject: Integrated Science  |  Strand: Cycles  |  Topic: Earth Science (The Carbon Cycle)

Curriculum reference: B8.2.1.1 Understand the carbon cycle and its significance in nature. Indicator B8.2.1.1.1: Describe the processes involved in the carbon cycle. All the exemplars are merged into one set of notes.

1. What is the Carbon Cycle?

Carbon is found in all living things, in the air as carbon dioxide, in fossil fuels and in rocks. The carbon cycle is the way carbon moves between the air, living things, the soil, the water and fossil fuels. The same carbon is used again and again.

2. Carbon Sources and Sinks

Carbon sources (give out carbon dioxide)	Carbon sinks (take in and store carbon)
Breathing (respiration) of plants and animals	Green plants and forests (photosynthesis)
Decay of dead plants and animals	The oceans, which dissolve carbon dioxide
Burning of wood, charcoal, petrol and diesel	Fossil fuels such as coal and oil, formed underground over millions of years
Bush burning and vehicle smoke	Limestone and shells

3. Processes in the Carbon Cycle

• Photosynthesis: green plants take carbon dioxide from the air and use sunlight to make food (sugar). Carbon moves from the air into plants.
• Feeding: animals eat plants (or other animals), so carbon passes along the food chain.
• Respiration: plants and animals use food to get energy and give out carbon dioxide into the air.
• Decomposition: bacteria and fungi break down dead plants and animals and return carbon dioxide to the air and the soil.
• Combustion: burning wood, charcoal, petrol, diesel and coal releases carbon dioxide into the air.

4. Drawing the Carbon Cycle

To draw the cycle, put carbon dioxide in the air at the top. Draw an arrow down to plants (photosynthesis). Draw arrows from plants to animals (feeding). Draw arrows from plants and animals back up to the air (respiration). Draw arrows from dead plants and animals to decomposers and back to the air (decomposition). Draw one more arrow from fuels and factories to the air (combustion).

5. Importance of the Carbon Cycle

• It supplies plants with the carbon dioxide they need to make food.
• It passes carbon to animals and people through food.
• It keeps the amount of carbon dioxide in the air in balance.
• Too much burning of fuel and cutting of forests adds too much carbon dioxide to the air. This traps heat and causes global warming.

Remember: Photosynthesis takes carbon dioxide out of the air. Respiration, decay and burning put it back.

Education Always (education.inspiringalways.com). Original notes written to follow the NaCCA Basic 8 Integrated Science curriculum.