1. Nutrient Cycles and Energy Flow
Lesson 3
August 26th, 2010

2. Review of what you covered
Biomes
Temperate Decidious forest
Tundra
Grassland
Boreal forest

3. Nutrient Cycles and Energy Flow
Nutrient – Substances that an organism uses to build and repair cells in the body.

4. Nutrient Cycles
In a cycle there is no beginning or end. Nutrients cycle back and forth between the biotic and abiotic parts of ecosystems. Water, carbon and nitrogen are nutrients that all have reservoirs.

5. The Water Cycle
The sun warms the surface water, and the water evaporates into the atmosphere.
The water vapour cools and condenses to form clouds.
Water falling from the clouds to the ground is called precipitation
Water that runs from the ground into streams or rivers is called run-off.

6. The Water Cycle
Some water seeps through the soil and into ground water. Large underground lakes are known as aquifers.
Plants absorb some of the water in the ground and release it through their leaves in a process known as transpiration
The water vapour rises and the cycle continues.

7. Do not copy this one

9. The Nitrogen Cycle All organisms need nitrogen to make proteins
78 % of the atmosphere is nitrogen but it cannot be directly used by organisms.
Organisms get nitrogen from substances that contain nitrogen.

10. The Nitrogen Cycle
The act of converting nitrogen gas (N2) to ammonia is called Nitrogen fixation
Nitrogen fixing bacteria perform this critical step
Without the bacteria the cycle would stop
Lighting only fixates 1% of the worlds nitrogen
Most plants cannot use the ammonia created

11. The Nitrogen Cycle
Nitrifying bacteria convert the ammonia into nitrates
Nitrates are absorbed and used by the plants
Animals eat plants to obtain nitrogen.
The animals then produce ammonia which is removed as waste.
Nitrifying bacteria then convert the ammonia to nitrates.
Denitrifying bacteria in the soil convert nitrates back into nitrogen gas.

12. Do not copy this

14. Read 62-65
Answer page 65 # 1, 3-6