4.8 – Describe the stages in the water cycle, including evaporation, transpiration,
condensation and precipitation.
– Evaporation: When water turns into water vapour due to heat.
– Transpiration: When water evaporates from the surface of a plant.
– Condensation: When water vapour turns back into water.
– Precipitation: When water is released from clouds.
4.9 – Describe the stages in the carbon cycle, including respiration, photosynthesis,
decomposition and combustion.
– Respiration: When organisms release carbon dioxide.
– Photosynthesis: When plants take in carbon dioxide.
– Decomposition: When decomposers decay dead matter, releasing carbon dioxide.
– Combustion: When matter is burned, releasing carbon dioxide.
4.10 – Describe the stages in the nitrogen cycle, including the roles of nitrogen
fixing bacteria, decomposers, nitrifying bacteria and denitrifying bacteria.
– Nitrogen-fixing bacteria: Converts nitrogen gas into ammonia.
– Decomposers: Break down matter and releasing nitrogen back into the air.
– Nitrifying bacteria: Converts nitrogen compounds into nitrites, then into nitrates.
– Denitrifying bacteria: Converts nitrates to nitrogen gas.
– Lightning: Converts nitrogen gas into nitrates and nitrites.
