Nutrient Cycles and Energy Flow SNC1P Findlay

Learning Goals Students will: Learn how nutrients are recycled through food chains. Learn about the water, carbon and nitrogen cycles.

Recycling of Atoms Atoms last forever. All the atoms on Earth today are the same as those that were present when Earth first formed. Every atom that makes up your tissues has a history! Atoms form elements which are pure substances that cannot be broken down into simpler substances.

What are nutrients? Nutrients come from food. They are substances that are used by an organism to build and repair the cells of the body.

Why are nutrients important? Nutrients in the food that you eat provides energy and matter that your body needs to stay alive. In fact 95% of our body is made up of just four of elements. Carbon, Hydrogen, Nitrogen, and Oxygen. Nutrients are recycled after they are used up.

How are nutrients recycled? A nutrient cycle shows how nutrients move between organisms and the environment. The following three cycles are especially important: Water cycle Carbon cycle Nitrogen cycle

Nutrient Cycle Producers get nutrients from the soil. Consumers get nutrients from eating producers or other consumers. Decomposers return nutrients to the soil through decomposition.

Water Cycle Water is removed throughout the entire biosphere. The sun inputs energy and the water evaporates into the atmosphere only to condense and fall back to Earth. The water collects in nearby streams, or rivers and is called run-off.

Water Cycle It sometimes seeps into the ground where it can be stored in large underground lakes. These lakes are called aquifers. Some of the water that remains on the surface is used by plants and animals to live and when they breathe it is transpired to the atmosphere only to begin the cycle again.

Carbon Cycle All living things contain carbon. Even though there is only 0.04% of the atmosphere being carbon dioxide, it is from this that the plants get the carbon to grow. Huge trees are massive and solid, but the vast majority of the matter that makes up a tree is carbon and this makes the worlds forests biotic reservoirs of carbon.

Carbon Cycle C can be found in the form of organic or inorganic substances. Organic compounds contain both carbon and hydrogen. e.g. CH4, C6H12O6 Inorganic compounds are all other compounds: they do not contain both C and H in their formula. e.g. CO2, H2O

Carbon Cycle There is another huge reservoir of carbon that sits underground. It is locked up in coal and oil which is almost entirely made of carbon. These stores are formed by ancient forests that were around millions of years ago that died and were converted into fossil fuels.

Carbon Cycle The last reservoir is the oceans. Carbon dioxide gas dissolves into the water and it is from this that the marine organisms build their tissues with.

Nitrogen Cycle All organisms need nitrogen to survive and the use of nitrogen is cycled through the ecosystem. Nitrogen makes up 78% of the atmosphere but can not be used directly from there. Organisms get their nitrogen from substances that contain nitrogen.

Where does nitrogen come from? The nitrogen within these substances comes from the atmosphere and is taken from the atmosphere by Nitrogen Fixing Bacteria. Converting Nitrogen gas (N2)to Ammonia (NH3), This process is called Nitrogen Fixation.

Nitrogen Cycle Nitrifying bacteria then convert the ammonia into nitrates which can be used by plants and animals. Fungi and bacteria then convert the waste from animals back into nitrates. To complete the cycle, denitrifying bacteria convert the nitrates back into nitrogen gas which returns to the atmosphere.