NUTRIENT CYCLING Science 10

Nutrient Cycles Because Earth is a closed system (i.e. there is little or no input of new material – we have what we have), nutrients are constantly recycled. The movement of nutrients through the environment are called nutrient cycles. In parts of these cycles, nutrients are in living organisms, or the biotic part of the environment. In other parts they are in the surrounding environment, or abiotic part.

Carbon Cycle There are 3 processes in the carbon cycle: 1. Photosynthesis 2. Cellular Respiration 3. Decomposition

Chemical Equation  Photosynthesis

Photosynthesis So three things are needed to make carbohydrates:  Carbon dioxide  Water  Energy from the Sun  Where do the water and carbon dioxide come from??

Photosynthesis Plants capture carbon from the atmosphere, in the form of carbon dioxide. This carbon dioxide is combined with water to make carbohydrates. Some of the carbon in the carbohydrates is used by the plants to make other carbon compounds, like fats and proteins. When consumers eat plants, the carbon compounds are made into animal tissues.

Important: Photosynthesis takes in carbon dioxide gas and gives off oxygen gas. Only producers can perform photosynthesis.

Cellular Respiration Organisms use carbohydrate molecules for energy. The actual carbon atoms are put back out into the atmosphere in the form of carbon dioxide.

Chemical Equation  Cellular Respiration

Important Cellular respiration takes in oxygen and gives off carbon dioxide. All organisms (producers and consumers) perform cellular respiration.

3. Decomposition When organisms die, their bodies still contain a lot of carbon. Carbon is also found in the feces and urine that organisms eliminate. Decomposers feed on this carbon (carbohydrates) and combine it with oxygen to perform cellular respiration.