Sustainable Ecosystems

Nutrient Cycles and Energy Flow All life on earth requires water and food. Water provides the liquid component that makes up cells Food provides nutrients

Nutrient Cycles and Energy Flow Nutrients are substances that an organism uses to build and repair the cells of its body Plants draw nutrients up from the soil and extract them from the air. They use sunlight and nutrients to make their own food

Nutrient Cycles and Energy Flow Food also contains energy along with nutrients, which organisms need to grow, maintain their bodies and reproduce

Nutrient Cycles and Energy Flow Nutrients include carbohydrates, fats and oils, proteins, vitamins and minerals. Nutrients are made up of elements –These are found on the periodic table Water is made up of the elements hydrogen and oxygen Sugar is made up of the elements: –Carbon, oxygen and hydrogen

Nutrient Cycles and Energy Flow 95% of our bodies are made up of just four elements: Carbon Hydrogen Oxygen Nitrogen

Nutrient Cycles and Energy Flow Nutrients cycle back and forth between the biotic and abiotic parts of an ecosystem This can happen fairly quickly or sometimes nutrients can get stored in reservoirs (e.g. glaciers or aquifers)

The Carbon Cycle

All living things contain carbon Carbon dioxide is made up of carbon and oxygen Carbon dioxide makes up 0.04% of all the gases in the atmosphere.

The Carbon Cycle Plants get all the carbon they need to grow from the carbon dioxide in the atmosphere through a process called photosynthesis Forests are a vast source of carbon

The Carbon Cycle Fossil fuels (coal, oil and natural gas) found underground are huge reservoirs of carbon These were formed from the compression of decomposed organisms that lived millions of years ago

The Carbon Cycle Another carbon reservoir is the oceans since carbon dioxide dissolves in water Marine organisms use this dissolved carbon to build their tissues

Photosynthesis The process of producing carbohydrates from carbon dioxide, water and sunlight CO 2 + H sunlight  C 6 H 12 O 6 + O 2 The sunlight in the above equation is captured by the plant’s chlorophyll

Photosynthesis Most of the oxygen we breath in comes from this reaction and accounts for about 21% of the atmosphere

Cellular Respiration Once plants have made glucose they must convert this into energy. They do this by cellular respiration O 2 + C 6 H 12 O 6  CO 2 + H 2 O + energy

Cellular Respiration The energy produced will run all the processes inside their cells Animals (and humans) also carry out cellular respiration They don’t use photosynthesis so we must obtain glucose by eating food containing carbohydrates

The Nitrogen Cycle

Nitrogen Cycle Nitrogen is used by organisms to make proteins Nitrogen gas which has the formula N 2 makes up 78% of the atmosphere but cannot be used in this form by most organisms

Nitrogen Cycle In a process called nitrogen fixation, nitrogen-fixing bacteria convert the nitrogen gas to ammonia (NH 3 ) Nitrogen-fixing bacteria are found in the nodules on the roots of plants called legumes (peas, beans, alfalfa)

Nitrogen Cycle Ammonia can be taken up by some plants but not most. One other natural way in which nitrogen gas is fixed to ammonia is through lightning.

Nitrogen Cycle Another process called nitrification is carried out by nitrifying bacteria. They take the ammonia and convert it into nitrites (NO 2 - ) and then into nitrates (NO 3 - ). Plants are able to absorb the nitrates through their roots

Nitrogen Cycle Animals obtain nitrogen by eating plants or other animals. When animals digest protein (which contains nitrogen) ammonia is produced. This ammonia is toxic to the animals, and is removed as waste

Nitrogen Cycle As waste, the ammonia is returned to the soil where it is once again converted to nitrites and nitrates Soil also contains denitrifying bacteria (microscopic bacteria, fungi, and other organisms) which converts nitrates back into nitrogen gas.

Nitrogen Cycle Nitrogen gas is released back into the atmosphere and the cycle can continue!

The Water Cycle