1. Cycles (Water, Carbon, Nitrogen)
Biological Cycles: repeating events that are needed for life to survive
Water Cycle
Carbon
Nitrogen
There are others important cycles as well that effect life
Phosphorus cycle, nutrient cycle, rock cycle, weather cycles

2. Learning Objectives:
Know all the basic steps of the Water, Carbon, & Nitrogen Cycles
Recognize what drives the Water Cycle and where fresh water comes from
Recognize what drives the Carbon Cycle and how it can be effected by human activities
Recognize the “weak points” in the Carbon & Nitrogen Cycles

3. Pg 75 THE WATER CYCLE Solar energy Transport over land Cloud movement
by wind
Precipitation
over land
Precipitation
over ocean
Evaporation &
transpiration
from land
Evaporation
from ocean
Percolation
through
soil
Runoff and
groundwater

4. Water Cycle (hydrologic cycle):
All water moves in a global cycle (it keeps a steady, but small, supply of fresh water available for human use)
powered by solar energy

5. Transpiration: loss of H20 by plant leaves as photosynthesis occurs (liquid vapor)

6. Evaporation: liquid H20  water vapor
(needs sunlight to the heat water)

7. Where does most rainwater come from in the world?

8. Water Cycle allows freshwater supplies on earth to be refilled

9. Water Cycle allows freshwater supplies on earth to be refilled

10. Problems in the Water Cycle

11. Pg 75 THE WATER CYCLE Solar energy Transport over land Cloud movement
by wind
Precipitation
over land
Precipitation
over ocean
Evaporation &
transpiration
from land
Evaporation
from ocean
Percolation
through
soil
Runoff and
groundwater

12. Pg 77 THE CARBON CYCLE CO2 in atmosphere Photosynthesis Cellular
respiration
Burning of
fossil fuels
and wood
Higher-level
consumers
Primary
consumers
Carbon compounds
in water
Decomposition

13. Carbon Cycle:
Reflects the reciprocal processes of photosynthesis and cellular respiration (metabolism)
Autotrophs/Producers get the carbon they need to make their food (photosynthesis) and to grow bigger in size from CO2 in the air, NOT the soil (nutrients and water only)
Heterotrophs/Consumers get the carbon they need to grow from their food, but also they release CO2 for respiration (cellular respiration)

14. Carbon Cycle: CO2 is a known greenhouse gas: (traps heat for sun)
The burning of fossil fuels (oil/coal) adds more CO2 to the atmosphere (so it is thought more heat will get trapped)
Note: the Greenhouse effect is a natural process that keeps the earth from cooling off too much
Global warming is thought to be the result of adding to much CO2 into the atmosphere, greatly increasing the greenhouse effect

16. Pg 77 THE CARBON CYCLE CO2 in atmosphere Photosynthesis Cellular
respiration
Burning of
fossil fuels
and wood
Higher-level
consumers
Primary
consumers
Carbon compounds
in water
Decomposition

17. Pg 78 End THE NITROGEN CYCLE N2 in atmosphere (use-less) Assimilation
Nitrogen-fixing
bacteria in root
nodules of legumes
Denitrifying
bacteria
NO3
Decomposers
Nitrifying
bacteria
Nitrification
Ammonification
NH3
NH4+
NO2 
Nitrogen-fixing
soil bacteria
Nitrifying
bacteria
End

20. The Nitrogen Cycle
Nitrogen fixation - Only a few types of bacteria (that live in the roots of plants called Legumes) can make
Useless N2
In the atmosphere
Useful ammonia
NH3
In the soil
Legumes

21. Consumers get the Nitrogen they need from eating plants (or animals that eat plants) after plants absorb nitrogen from the soil/oceans
Consumers return nitrogen to soil/oceans with wastes like urine (urea is a molecule with nitrogen) and when organisms bodies decay in the soil
Nitrogen in the soil may be returned to the atmosphere after denitrification (another bacteria does this)
Urea

22. Nitrogen based-molecules (like ammonia) are also used a lot in fertilizers to increase the size and growth rate of plants

23. Pg 78