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Oxidation of food materials (breaking of C-C bonds in complex molecules) within the cell to release energy for ATP synthesis is called cellular respiration.
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This energy supports processes like absorption, transport, movement, reproduction, and breathing.
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The ultimate source of food respired is photosynthesis.
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Compounds oxidized during respiration are called respiratory substrates, e.g., carbohydrates (most common), proteins, fats, and organic acids.
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The released energy is used to synthesize ATP, which, when broken down, provides energy. Thus, ATP acts as the energy currency of the cell.
Breathing in Plants
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For respiration, plants take in O₂ and release CO₂.
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Gas exchange occurs via stomata and lenticels.
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Plants lack specialized respiratory organs because:
- Each plant part handles its own gas-exchange needs, limiting gas transport.
- Gas exchange is very low compared to animals.
- Leaves are adapted for maximum gas exchange during photosynthesis, releasing O₂ within the cell.
- Most living cells contact air, located near the plant surface. In stems, living cells form thin layers beneath the bark with lenticels. In leaves, stems, and roots, loosely packed parenchyma cells provide interconnected air spaces.
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Complete combustion of glucose yields energy, much of which is released as heat.
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This energy is used to synthesize other molecules.
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Glucose catabolism occurs in small steps, allowing some steps to couple released energy to ATP synthesis, preventing all energy from being lost as heat.
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During respiration, oxygen is utilized, and CO₂, water, and energy are released.
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Certain organisms adapt to anaerobic conditions, either as facultative anaerobes or obligate anaerobes.
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy
Very .. useful.tq so much
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