Nutrient Cycling

What is aerobic respiration by autotrophs dependent on?

Atmospheric oxygen produced by photosynthesis.

What is photosynthesis dependent on?

Atmospheric carbon dioxide produced by respiration by heterotrophs.

What chemical elements do living organisms need?

• Carbon, hydrogen, and oxygen to make carbohydrates, lipids, and other carbon-containing compounds.

• Nitrogen is needed to make amino acids, DNA, proteins

• Phosphorus is needed to make DNA and ATP

How do chemical elements required by living organisms recycle in ecosystems?

Through nutrient cycles, such as the carbon or nitrogen cycle.

What role do decomposers (saprotrophs and detritivores) play in ecosystems?

They break down body parts of dead organisms or organic matter left in feces.

How do decomposers convert nutrients from complex organic matter?

Using digestive enzymes to convert the nutrients in complex organic matter into a more usable form for themselves and other organsms

What role do bacteria play in the nitrogen cycle?

They trap nitrogen from the air or the form of proteins, enzymes, and DNA from dead organisms.

How are nitrates formed in the nitrogen cycle?

Bacteria convert nitrogen into ammonia and ammonium, and finally into useful nitrates.

How can nitrates be utilized by plants and animals?

Plants can assimilate nitrates to incorporate them back into proteins or chlorophyll, and animals can eat these plants to use the nitrogen.