5.10: Dependence of Aerobic Respiration on Oxygen

Photosynthesis

Release of Oxygen through its removal from water by breaking covalent bonds 

• Utilizes light energy and is catalysed by oxygen-evolving complex

• Process evolved in archaebacteria billions of years ago 

  • Allows the release of oxygen into Earth’s atmosphere → Started the development of aerobic respiration

• Respiring heterotrophs dependent on photosynthesizing autotrophs for oxygen and vice versa

Respiration

Release CO₂ that helps limit the rate of photosynthesis

• Does this through the use of O₂ from the autotrophs 

GLobal Fluxes for CO₂ and O₂

Hard to quantify…

Measurements are produced on individual ecosystems or mesocosms

• Mesocosm: Any outdoor experimental system that examines the natural environment under controlled conditions

• Units are large - Gigatonnes = 10¹⁵ grams

  • Terrestrial ecosystems have 120 gigatonnes of carbon is circled

Chemical element supply needed for living organisms

1. Carbohydrates, lipids and other C-compounds: Carbon, hydrogen and oxygen 

2. DNA: Nitrogen and phosphorus 

3. 15 other elements are also needed like sulfur for proteins

Autotrophs element gains

• They gain them through their abiotic environment or synthesis it themselves

  • Absorb the recycled elements around them 

Heterotrops in gaining elements

• Obtained through eating other organism that have the needed elements or compounds 

  • These elements keep getting recycled for years to come - despite having a limited amount we don’t run out 

    • Return the used elements to the environment 

Decomposers

•  The ones who break down carbon compounds to help with recycling 

  • Nutrient cycle: The recycling of elements that an organism needs

    • Eg, Carbon or nitrogen