SustainableEcosystems

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)

https://www.youtube.com/watch?v=2D7hZpIYlCA

The Carbon Cycle

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

CO2 + H20 + sunlight C6H12O6 + O2

• 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

O2 + C6H12O6 CO2 + H2O + 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 Cyclehttps://www.youtube.com/watch?v=oy8e2HrOh6Q

• Nitrogen is used by organisms to make proteins

• Nitrogen gas which has the formula N2 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 (NH3)

• 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 (NO2

-) and then into nitrates (NO3-).

• 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