What is the significance of step-wise release of energy in respiration?
The step-wise release of energy during respiration is highly significant for the efficient functioning of living cells. During oxidation within a cell, all the energy contained in respiratory substrates is not released free into the cell, or in a single step.
Instead, energy is released in a series of slow step-wise reactions controlled by enzymes. This controlled release allows the energy to be trapped as chemical energy in the form of ATP. The energy released by oxidation in respiration cannot be used directly.
The step-wise release enables the synthesis of ATP, which acts as the energy currency of the cell. ATP is broken down whenever and wherever energy needs to be utilised by the cell.
This energy trapped in ATP is utilised in various energy-requiring processes of the organisms. Additionally, the carbon skeleton produced during respiration is used as precursors for biosynthesis of other molecules in the cell.
This demonstrates the beauty and efficiency of the living system in extraction and storing energy.
Explanation
The textbook emphasizes that energy release in respiration is controlled and gradual, not sudden. Key points include: (1) Energy is NOT released freely or in a single step - it's released in slow, enzyme-controlled reactions; (2) This allows energy to be trapped as ATP rather than being lost; (3) ATP serves as energy currency that can be used whenever/wherever needed; (4) The carbon skeleton produced serves as precursor for biosynthesis. The step-wise nature demonstrates the 'beauty and efficiency' of living systems.