This document summarizes the cycling of important materials like water, carbon, nitrogen, and phosphorus through ecosystems. It explains that while energy is lost at each trophic level, the sun replenishes it, and matter is recycled as nutrients move through organisms. The atoms that make up living things today have been on Earth since life began. It then provides more detailed explanations of the water, carbon, nitrogen, and phosphorus cycles.

1. 2.3 Cycling of Matter

2. 3 Important Materials That Cycle
Through Ecosystems
 Water
 Carbon
 Nitrogen
 As well as sulfur, calcium, and
phosphorus among others

3. Energy is lost:
 at each transition from one trophic
level to the next
 But the sun replenishes the energy
 Matter is recycled!

4.  Matter in the form of nutrients
also moves through the
organisms at each trophic level
 The atoms of elements that
make up the bodies of organisms
alive today are the same atoms
that have been on Earth since
life began

5. Water cycle
 plants absorb water through roots
 animals drink water or get it from food
 water is lost through respiration, excretion
and decomposition of dead organisms
 Animated water cycle
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7. The Carbon Cycle
 carbon is found as CO2 in the
atmosphere & ocean
 producers (terrestrial & aquatic) use CO2
in photosynthesis to make sugar
 photosynthesis = CO2 + H2O -> carbs.
 respiration & decay return CO2 to the
atmosphere
 burning returns CO2 to atmosphere

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11. The Nitrogen Cycle
 makes up 78% of the atmosphere
 living things cannot use nitrogen in
atmospheric form
 lightening and bacteria “fix’ into usable
compounds called nitrates
 plants convert nitrates into molecules
containing nitrogen

12. The Nitrogen Cycle (cont.)
 animals change these molecules into
animal proteins
 during digestion, humans convert
plant & animal proteins into human
proteins
 decay returns nitrogen to the
atmosphere

13. The nitrogen cycle (cont.)

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16. The Phosphorus Cycle
 short term cycle - plants use
phosphorus from the soil into body
tissues
 animals get phosphorus by eating
plants
 decay returns phosphorus to the
soil

17. The Phosphorus Cycle
 long term cycle - phosphorus
washed into the sea becomes
incorporated into rock
 years later rock containing
phosphorus is exposed -
phosphorus is released