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Flashcards in Nutrient Cycles Deck (3)
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1

Describe the carbon cycle

- Carbon compounds in plants formed millions of years ago from dead vegetation to form fossil fuels - oil, coal, peat, gas
- Carbon compounds in plants are eaten by animals => respiration and decay releases carbon dioxide
- Burning fossil fuels emit co2
- Co2 is taken in plants for photosynthesis
(pg230)

2

Describe the water cycle

- Energy from sun powers the water cycle
- Evaporation from sea
- Condensation of water to form cloud containing water droplets
- Gets colder as air rises. More water condenses out => droplets get bigger and heavier and fall as precipitation
- Water vapour from plants and animals return to the sea

3

Describe the nitrogen cycle

- Enormous amounts of energy from lightning can break nitrogen allowing it to combine with oxygen to form nitrogen oxides to form NO3 (nitrate ions)
- NO3 enters the soil and is absorbed by plants through roots. Uses this nitrogen to make proteins.
- Nitrogen gas can enter the root. Nitrogen-fixing bacteria (found in root nodules of leguminous plants) can turn nitrogen gas into nitrates. This process is nitrogen fixation
- Animals eat plants and digest => when excrete/die, nitrifying bacteria break down proteins in the dead organism releasing nitrates into soil
- Denitrification is when denitrifying bacteria in soil break down nitrates and release nitrogen gas into the air