biology carbon cycle and water cycle

carbon cycle

• co2 removed from the air by photosynthesis done by plants and algae.

• they use the carbon to make glucose

• co2 returns to the air when plants, algae + animals respire

• co2 also returns to the air when wood and fossil fuels are burned in combustion water cycle

water cycle

• sun causes water to evaporate from seas and lakes, forming water vapour

• water vapour rises and condenses to form clouds

• then returns to land by rain, snow or hail this water returns to lakes to provide water for plants and animals

• then it runs into seas and the cycle begins again

how is the water cycle important for potable water

• in areas of drought the water cycle is used to make potable water.

• desalination is done to remove salt from seawater, to make it drinkable

• desalination is performed by reverse osmosis

nitrates

• nitrate-fixing bacteria is present in nodules of plants.

• it converts nitrogen gas into nitrates

• the haber process converts hydrogen to ammonia

• plants absorb nitrates through active transport

why is nitrogen used in fertilisers

• nitrogen is used in fertilisers in the form of ammonium nitrate

• so that plants get artificial nitrates without needing to rely on nitrogen-fixing bacteria