1.3 Big Idea 2: Energy & Molecular Building Blocks

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1. Life requires outside source of nutrients and energy

   1. A major component of ecosystems is the movement of matter and energy

   2. Food provides:

      1. nutrients which are the chemical building blocks 

      2. energy which is the capacity to do work which in living things maintains the function of cells

      3. metabolism  is the totality of chemical reactions occurring within an organism

2. Sunlight is the ultimate source of energy for nearly all life on Earth

   1. plants and certain other organisms (such as algae) are able to collect solar energy and transform it into chemical energy placed into organic molecules (like carbohydrates, etc.) through photosynthesis

   2. all life on Earth acquires energy by metabolizing nutrient molecules made by photosynthesizers 

3. Nutrients (molecules) and energy flow between organisms defines ecosystem functions

   1. nutrient chemicals cycle between the living and nonliving parts of an ecosystem 

      1. nutrients can be examined as their chemical elements such as carbon, oxygen, hydrogen, and nitrogen

      2. plants link the inorganic molecules and organic molecules through their processes

      3. the process of making organic molecules requires solar energy

      4. organic chemical molecules flow through food chains until they reach decomposers where they are returned to the the nonliving parts of the ecosystem

   2. energy flows through food chains through the bonds by making organic molecules

      1. solar energy enters the living parts of an ecosystem through photosynthesis where the energy is placed in the carbon-carbon bonds in organic molecules

      2. energy is transferred to other organisms through feeding relationships

         1. energy gradually dissipates with its transfer and released as heat in the environment

         2. energy does not cycle and ecosystems require a constant supply of solar energy

4. The climate where an ecosystem is found affects what organisms can exist at that location

   1. temperature, precipitation, and latitude affects where different ecosystems are found

   2. elevation also impacts the type of ecosystems found at different locations

   3. example: deserts exist in areas of minimal rain compared to forests which require much more precipitation

   4. two most biologically diverse ecosystems due to high solar energy input:

      1. tropical rainforests

      2. coral reefs

5. homeostasis is the ability of organisms (even single-celled simple life) to maintain a stable biological balance

   1. physiological factors must remain within a tolerance range, examples: 

      1. temperature

      2. moisture level

      3. acidity 

   2. maintained by systems that monitor internal conditions

   3. organisms make adjustments behaviorally or physiologically to keep within tolerance

      1. feedback is where a chemical reaction is amplified (increased output of a product) or is halted (decrease in an output of a product)

      2. control mechanisms might be the interactivity among and between systems through metabolism