SCI 11: Module 3 Energy Flow and Biogeochemical Cycles

• The flow of energy is the essence of life, specifically, of living systems.
• Energy is the ability to do work, and it is everywhere.
• Different forms of Energy: Mechanical Energy (kinetic energy), Potential Energy (stored energy), Radiant Energy, Sound Energy, Chemical Energy, Heat Energy, Electrical Energy, and Nuclear Energy.
• Radiant / Solar energy - The energy from the sun that is used for photosynthesis.
• Chemical energy - the energy stored in food or fuel.
• Mechanical Energy - the energy used in movement.
• Potential Energy - stored energy; energy at rest.
• Electrical Energy - the energy of particles moving through a wire.
• Sound Energy - a form of energy we can hear; produced when an object vibrates and disturbs air particles.
• Heat Energy - energy produced when particles of substances collide with each other.
• Energy may also be sourced from renewable or non-renewable sources.
• Non-renewable resources supply the bulk of our energy needs because technologies allow them to be harnessed on a large scale to meet consumer needs.
• The Law of Thermodynamics - basis of the flow of energy.
• The first law of Thermodynamics (The Law of Conservation of Energy) - concerns the amount of energy in the universe- it is constant; energy cannot be created or destroyed.
• Second Law of Thermodynamics - energy cannot be changed without some conversion into heat energy; disorder (entropy) in the universe is decreasing.
• As energy is changed from one form to another, part if that energy assumes waste form (heat energy); consequently, the capacity of energy to do work is decreased.
• The primary source of energy is the sun.
• Only 2% of the total light is used to make food through photosynthesis, while most of the light is transformed as heat.
• How is energy acquired?

  Photosynthesis, Chemosynthesis, Heterotrophs (eating other living or dead organisms)
• Photoautotrophs - organisms that use light energy to make their own food; harness radiant energy and convert it to chemical energy in the form of ATPs (adenosine triphosphates), to be used to synthesize complex organic molecules like glucose.
• Autotrophs - the foundation of every ecosystem on Earth; form the base of food chains and food webs, and the energy they capture from light or chemicals sustains all the other organisms in the community.
• Chemoautotrophs - organisms that create their organic food from inorganic chemicals like iron, nitrogen, sulfur, and magnesium; supplies energy to the rest of the ecosystem.
• Heterotrophs - organisms that obtain energy from other organisms; cannot capture light or chemical energy to make food.
• Trophic levels - a feeding level, often represented in a food chain or food web.
• Primary producers constitute the bottom trophic level, followed by primary consumers (herbivores), secondary consumers, tertiary consumers, etc.
• Only about 10% of net energy production at one trophic level is passed on to the next level because processes like respiration, growth, reproduction, etc reduce energy flow.
• The nutritional quality of the consumed material affects how efficiently energy flows.
• Ecological pyramids (trophic pyramids) - are graphical representations designed to show relationships between energy and trophic levels in an ecosystem
• Pyramid of energy - most useful; shows the relationship between energy and trophic leve;
• Biological magnification / biomagnification - the increase in the concentration of a contaminant (toxic substance) in an organism due to the accumulation of the contaminant in the primary producers.
• Energy flows in one direction through ecosystems, entering as sunlight (or inorganic molecules through chemoautotrophs) and leaving as heat during many transfers between trophic levels.
• Matter that makes up living organisms is conserved and recycled.
• Earth is a closed system for matter; thus, all elements needed for living systems came from what was present in the Earth's crust so many billion years ago; matter is continually recycled.
• Elements are the critical components of life and must be available for biological processes.
• Biogeochemical cycle - recycling inorganic matter between living organisms and their environment.
• Biogeochemical cycles serve various functions at the ecosystem level and ensure the survival of various organisms.

  • Transformation of matter from one form to another; utilization of matter in a form specific to a particular organism.
  • Enable the transfer of molecules from one locality to another.
  • Facilitate the storage of elements.
  • Assist in the functioning of ecosystems.
  • Link living organisms with living organisms, then linking living organisms with abiotic factors.
  • Regulate the flow of substances.
• Radiant energy powers processes like photosynthesis and evaporation; and drives the cycle that involves reservoirs where chemicals are stored or concentrated for long periods.
• Five most common elements associated with organic molecules: hydrogen and oxygen, carbon, nitrogen and phosphorous.