Cellular respiration and photosynthesis are essentially opposite processes in the flow of energy and matter in ecosystems, and they complement each other in the carbon cycle.
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Chemical Reactions:
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Photosynthesis: The general equation for photosynthesis can be written as: \[ 6 \text{CO}_2 + 6 \text{H}_2\text{O} + \text{light energy} \rightarrow \text{C}6\text{H}{12}\text{O}_6 + 6 \text{O}2 \] In this process, carbon dioxide (\(CO_2\)) and water (\(H_2O\)) are converted into glucose (\(C_6H{12}O_6\)) and oxygen (\(O_2\)) using light energy, typically from the sun.
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Cellular Respiration: The general equation for cellular respiration is the reverse of that for photosynthesis: \[ \text{C}6\text{H}{12}\text{O}_6 + 6 \text{O}_2 \rightarrow 6 \text{CO}_2 + 6 \text{H}_2\text{O} + \text{ATP (energy)} \] In this process, glucose and oxygen are used to produce carbon dioxide, water, and energy (in the form of ATP).
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Energy Input and Output:
- Photosynthesis: This process is endergonic, meaning it requires an input of energy (from sunlight) to convert inorganic molecules (CO2 and H2O) into organic molecules (glucose).
- Cellular Respiration: This process is exergonic, meaning it releases energy by breaking down organic molecules (glucose) into inorganic molecules (CO2 and H2O).
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Organisms Involved:
- Photosynthesis: Primarily occurs in plants, algae, and some bacteria that contain chlorophyll and can capture sunlight.
- Cellular Respiration: Occurs in all living organisms, including plants, animals, and microbes, as it is essential for producing the energy required for cellular functions.
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Role in the Ecosystem:
- Photosynthesis: Converts solar energy into chemical energy stored in glucose, which forms the basis of the food chain.
- Cellular Respiration: Releases the energy stored in glucose for use by cells, and produces waste products (CO2 and water) that can be used again in photosynthesis.
In summary, photosynthesis converts light energy into chemical energy, while cellular respiration releases that chemical energy for cellular activities, highlighting the cyclical nature of energy flow in ecosystems.