Transcript snc1d u1 lesson 3 nutrient cycles and energy flow
Nutrient Cycles and Energy Flow
Lesson 3 August 26 th , 2010
Review of what you covered
◦ ◦ ◦ Biomes ◦ Temperate Decidious forest Tundra Grassland Boreal forest
Nutrient Cycles and Energy Flow
Nutrient – Substances that an organism uses to build and repair cells in the body.
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.
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.
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.
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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.
The Nitrogen Cycle
The act of converting nitrogen gas (N 2 ) to ammonia is called
Nitrogen fixation
Nitrogen fixing bacteria
critical step ◦ perform this Without the bacteria the cycle would stop Lighting only fixates 1% of the worlds nitrogen Most plants cannot use the ammonia created
The Nitrogen Cycle
Nitrifying bacteria
into nitrates convert the ammonia 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.
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Read 62-65 Answer page 65 # 1, 3-6