Write down the equations of both cellular respiration and photosynthesis. Describe where each of these processes takes place and what reactions are involved. Do some research into how animals and plants perform these processes and what benefits they derive from them. Then identify how carbon is cycled, and relate that to the global carbon cycle. Investigate how human impacts are changing the carbon cycle, and what, if any, impact it has on the two processes.

Answer 1

Equations

1. Cellular Respiration: The general equation for cellular respiration in aerobic organisms is: \[ \text{C}6\text{H}{12}\text{O}_6 + 6 \text{O}_2 \rightarrow 6 \text{CO}_2 + 6 \text{H}_2\text{O} + \text{Energy (ATP)} \]

   • Reactants: Glucose and oxygen
   • Products: Carbon dioxide, water, and energy (ATP)

2. Photosynthesis: The general equation for photosynthesis is: \[ 6 \text{CO}_2 + 6 \text{H}_2\text{O} + \text{Light Energy} \rightarrow \text{C}6\text{H}{12}\text{O}_6 + 6 \text{O}_2 \]

   • Reactants: Carbon dioxide, water, and light energy
   • Products: Glucose and oxygen

Locations of Processes

• Cellular Respiration occurs in:

  • Eukaryotic Cells: It primarily takes place in the mitochondria, where aerobic respiration occurs. The glycolysis phase occurs in the cytoplasm.
  • Prokaryotic Cells (like bacteria): It occurs in the cell membrane.

• Photosynthesis occurs in:

  • Plants: In chloroplasts located in the cells of leaves primarily. The light-dependent reactions occur in the thylakoid membranes, and the light-independent reactions (Calvin cycle) occur in the stroma.

Reactions Involved

• Cellular Respiration:

  1. Glycolysis: Breakdown of glucose into pyruvate, yielding ATP.
  2. Krebs Cycle: Further breakdown of pyruvate, producing electron carriers (NADH and FADH2) and CO2.
  3. Electron Transport Chain: Utilizes electrons from carriers to produce the majority of ATP and water.

• Photosynthesis:

  1. Light-dependent Reactions: Capture light energy to produce ATP and NADPH while splitting water and releasing oxygen.
  2. Calvin Cycle (Light-Independent Reactions): Utilizes ATP and NADPH to convert CO2 into glucose.

Benefits Derived from the Processes

• Cellular Respiration:

  • Organisms (including animals, plants, fungi) derive ATP, the energy currency necessary for cellular functions, growth, and maintenance.
  • It allows for the efficient extraction of energy stored in glucose.

• Photosynthesis:

  • Plants produce glucose, which serves as a primary energy source for growth and metabolism.
  • Oxygen produced during the process is essential for aerobic life forms.

Carbon Cycling

The carbon cycle involves the continuous movement of carbon among the atmosphere, oceans, soil, plants, and animals. Key components include:

• Photosynthesis: Plants absorb CO2 and convert it into organic matter (glucose).
• Cellular Respiration: Organisms (including animals and plants) release CO2 back into the atmosphere through respiration.
• Decomposition: Dead organic matter decomposes and releases carbon back to the soil and atmosphere.
• Fossil Fuels: Carbon stored in fossil fuels is released by combustion.

Global Carbon Cycle

The global carbon cycle is influenced by biotic (living organisms) and abiotic (atmosphere, oceans) processes that store carbon in different reservoirs. The balance of these processes helps regulate Earth's climate and support life by cycling carbon continuously.

Human Impacts on the Carbon Cycle

Human activities, particularly fossil fuel combustion, deforestation, and industrial agriculture, have significantly altered the carbon cycle:

• Increased Carbon Dioxide Emissions: Emissions from burning fossil fuels contribute to atmospheric CO2 levels, enhancing the greenhouse effect and global warming.
• Deforestation: Reduces the number of trees available to absorb CO2, disrupting the carbon sequestration process.
• Land Use Changes: Agricultural practices can release stored carbon from soil and vegetation.

Impact on Cellular Respiration and Photosynthesis

• Cellular Respiration: Increased CO2 levels may enhance plant respiration rates, but the primary concern is that elevated temperatures can stress organisms and alter metabolic rates negatively.
• Photosynthesis: Elevated CO2 can initially enhance photosynthesis in some plants, but climate change effects (like droughts, extreme weather) can hinder growth and disrupt ecosystems.

Human-induced changes to the carbon cycle pose challenges to both processes, affecting energy availability, ecosystem balance, and overall biodiversity. Addressing these changes is critical to sustaining both photosynthesis and respiration as part of the broader earth system.