Dissolved carbon dioxide is stored in oceans. Marine organisms store carbon-rich carbonate (CO3 2- ) in their shells, which eventually form sedimentary rock.

Causes of Pollution

is a major problem that is yet to be solved.

occurs mainly through nitrogen-fixing bacteria, and when lightning strikes in the atmosphere.

plants and animals obtain energy by converting carbohydrates and oxygen (O2) into carbon dioxide and water.

are chemicals required for plant and animal growth and other life processes

Ammonium is converted into nitrate and nitrite (NO2- ) through the work of nitrifying bacteria.

This is a natural system altered by men through agricultural activity.

is an essential component of cells and life-sustaining chemical reactions.

The second trophic level of organisms gets energy by eating other organisms.

break down dead or decaying consumers and producers via chemical reactions and use the energy released from rearranging those molecules for growth and development.

through chemical or physical means—breaks down rock, releasing phosphate into the soil from longer-term stores.

show the flow of energy from plant to animal and from animal to animal.

is a model that shows the loss of energy from one trophic level to another

is a chemical reaction that converts solar energy and atmospheric carbon dioxide gas (CO2) into chemical energy.

Denitrifying bacteria convert nitrate back into atmospheric nitrogen

describes the breakdown of organic wastes and dead organisms.

Nitrogen gas is converted into nitrate (NO3 - ) and ammonium (NH4 +), compounds that are usable by plants.

is an important component of DNA and proteins

describe the flow of nutrients in and out of stores as a result of biotic and abiotic processes

is the transfer of energy from one organism to another in an ecosystem

carries energy to cells.

Interconnected food chains are illustrated in a model called

The first trophic level includes organisms that are called

Nutrient cycles

Useable forms of nitrogen are taken up by plant roots and incorporated into plant proteins.