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Updated Mar 22, 2026

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3 pages

Nitrogen, Carbon, and Water Cycles for EDEXCEL Science

Zara

@zara_12321

Ever wondered how nature recycles everything perfectly? The carbon, water,... Show more

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# Carbon cycle

Fossil fuels are made
of decayed plant and
animal matter.

Burning

Products made
from plants and
animals

Burning

CO, in t

The Carbon Cycle

Your body is made of carbon, and so is every living thing on Earth! The carbon cycle shows how this essential element moves between the air, plants, animals, and soil in an endless loop.

Photosynthesis kicks off the whole process when green plants grab CO₂ from the air to make food. When animals eat plants, they're getting those carbon compounds too. Both plants and animals release CO₂ back into the air through respiration - basically just breathing!

When living things die, decomposer bacteria and fungi break them down, releasing more CO₂. We also burn things like wood and fossil fuels (made from ancient dead plants and animals), which pumps even more CO₂ back into the atmosphere.

Key Point: The carbon cycle has multiple pathways, but they all lead back to CO₂ returning to the air - it's nature's perfect recycling system!

The Water Cycle

Think about the last time you saw water evaporate from a puddle - you were watching the water cycle in action! This process moves water around Earth using the sun's energy as the driving force.

Evaporation happens when the sun heats up water from oceans, lakes, and rivers. Plants also release water vapour through their leaves in a process called transpiration - they're basically sweating!

As water vapour rises high into the sky, it cools down and condenses into tiny droplets that form clouds. Eventually, this water falls back down as precipitation (rain, snow, or sleet), filling up our rivers, lakes, and underground water stores again.

Key Point: The water cycle is powered entirely by the sun's heat - it's like a giant solar-powered recycling machine!

The Nitrogen Cycle and Water Scarcity

Here's something mad - the air around you is 78% nitrogen, but plants can't use it directly! The nitrogen cycle solves this problem through some clever natural processes.

Lightning is so hot it breaks down nitrogen gas and creates nitrates that dissolve into soil. Special nitrogen-fixing bacteria also convert nitrogen into ammonia that plants can actually absorb through their roots to make proteins and DNA.

When animals eat plants, they get these nitrogen compounds. Animal waste and dead organisms return nitrogen to the soil, where decomposer bacteria break it down, and nitrifying bacteria convert it back into forms plants can use again.

During droughts, when there's little rainfall, we can create potable water (safe drinking water) through desalination - basically removing salt from seawater by evaporating and condensing it.

Key Point: Each cycle depends on different types of bacteria to keep the recycling process going - microorganisms are the unsung heroes of life on Earth!

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Updated Mar 22, 2026

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3 pages

Nitrogen, Carbon, and Water Cycles for EDEXCEL Science

Zara

@zara_12321

Ever wondered how nature recycles everything perfectly? The carbon, water, and nitrogen cycles are Earth's brilliant recycling systems that keep life going by constantly moving essential materials around our planet.

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The Carbon Cycle

Your body is made of carbon, and so is every living thing on Earth! The carbon cycle shows how this essential element moves between the air, plants, animals, and soil in an endless loop.

Key Point: The carbon cycle has multiple pathways, but they all lead back to CO₂ returning to the air - it's nature's perfect recycling system!

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The Water Cycle

Think about the last time you saw water evaporate from a puddle - you were watching the water cycle in action! This process moves water around Earth using the sun's energy as the driving force.

Key Point: The water cycle is powered entirely by the sun's heat - it's like a giant solar-powered recycling machine!

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Improve your grades

Join milions of students

The Nitrogen Cycle and Water Scarcity

Here's something mad - the air around you is 78% nitrogen, but plants can't use it directly! The nitrogen cycle solves this problem through some clever natural processes.

Key Point: Each cycle depends on different types of bacteria to keep the recycling process going - microorganisms are the unsung heroes of life on Earth!