Biol005c Module 4 Learning Objectives

Identify and describe the biotic and abiotic components of ecosystems, and construct models that show how energy flows and matter cycles through ecosystems.

Biotic components of ecosystems include all living organisms and dead organic matter/waste, while abiotic components of ecosystems include nutrients, energy, water, and minerals.

Trace the movement and transformation of water, carbon, nitrogen, and phosphorus through biotic and abiotic reservoirs, including the major processes that transfer materials between reservoirs.

• Water:

  • think of the water cycle (evaporation, transpiration, condensation, precipitation)

  • reservoirs include oceans, glaciers, ice caps, lakes, and rivers

• Carbon:

  • photosynthetic organisms convert atmospheric CO2 into glucose that can be consumed by heterotrophs, consumers breathe out CO2 via cellular respiration, volcanoes and burning of fossil fuels contribute to atmospheric CO2

  • reservoirs include fossil fuels, soil, and atmosphere

• Nitrogen:

  • atmospheric nitrogen can be taken up by nitrogen-fixing bacteria (nitrogen fixation) or decomposed by decomposers (ammonification) and can be converted into nitrate and ammonium for plant use

  • main reservoir is the atmosphere

• Phosphorus:

  • rock weathering releases phosphate into soil and reaches aquatic systems through leaching, phosphate is returned by decomposition or excretion by consumers

  • reservoirs include sedimentary rocks of marine origin, soil, and organisms

Differentiate between organic and inorganic forms of biologically important elements and explain how organisms obtain and transform these materials through processes such as photosynthesis, respiration, decomposition, nitrogen fixation, and ammonification.

• Carbon:

  • Organic: carbohydrates, lipids, proteins

  • Inorganic: atmospheric gas

  • Photosynthesis converts CO2 (inorganic) into glucose (organic)

  • Consumers exhale CO2 (inorganic) and return it back to the environment via cellular respiration

  • Decomposition breaks down CO2

• Nitrogen:

  • Organic: amino acids, nucleic acids

  • Inorganic: atmospheric gas, ammonium, nitrate

  • Nitrogen-fixing bacteria converts atmospheric nitrogen (inorganic) into ammonium and nitrate (inorganic) for plant use via nitrogen fixation

  • Decomposers break down atmospheric nitrogen (inorganic) into ammonium and nitrate (inorganic) for plant use via ammonification and decomposition

• Phosphorus:

  • Organic: nucleic acids, phospholipids, ATP

  • Inorganic: phosphate

  • Weathering of rocks releases phosphate (inorganic) into soil and reaches aquatic systems through leaching

  • Decomposition breaks down phosphate

Explain how microbes, decomposers, and detritivores regulate nutrient availability and contribute to ecosystem productivity and nutrient cycling.

Microbes, decomposers, and detritivores break down dead matter, and when they die, these inorganic compounds (like nitrate and ammonium) and nutrients are returned to the soil, regulating nutrient availability and contributing to ecosystem productivity and nutrient cycling.

Analyze how nutrient availability can limit biological growth and predict how ecological interactions and environmental conditions influence rates of nutrient cycling within ecosystems.

If there is not many nutrients available, organisms are not able to grow properly and benefit from them. To prevent this, it is important for an ecosystem to maintain high productivity (more moisture, higher temperatures) and biodiversity as this allows for more nutrients to be recycled.

Evaluate how human activities, including agriculture and fertilizer use, alter biogeochemical cycles and affect nutrient movement, storage, and ecosystem function.

When humans harvest plants from a farm, they are removing nutrients from the soil. Adding fertilizer helps return those nutrients back to the soil and can even increase the amount of nutrients in the soil.