In Respiration -

Options

A. Dry wt decrease
B. C-C bonds of complex compounds break through oxidation in cells
C. Energy contained in the respiratory materials is released in a series of slow stepwise reactions controlled by enzymes
D. All

Answer

**Step-by-Step Text Solution:**

1. **Definition of Respiration**: Respiration is defined as a physio-chemical process that involves both physical and chemical changes. It is essential for the survival of living organisms as it provides energy.

2. **Nature of Respiration**: Respiration is primarily a catabolic process. This means that it involves the breakdown of larger molecules into smaller ones, leading to a decrease in dry weight.

3. **Breakdown of Complex Molecules**: During respiration, complex compounds undergo oxidation, which breaks the carbon-carbon bonds. This breakdown is crucial for releasing energy.

4. **Energy Release**: The energy contained in the respiratory material (most commonly carbohydrates like glucose) is released in a series of slow, stepwise reactions. These reactions are controlled by enzymes, ensuring that the energy is released efficiently and not all at once.

5. **Gas Exchange**: The physical aspect of respiration involves the exchange of gases, primarily oxygen and carbon dioxide. This gas exchange is vital for the process to occur.

6. **Chemical Energy Production**: The chemical aspect of respiration results in the production of ATP (adenosine triphosphate), which serves as the energy currency of the cell. ATP is essential for various cellular processes.

7. **Substrate Utilization**: The most common substrate for respiration is glucose, a six-carbon compound. Through a series of reactions, glucose is broken down into pyruvate, a three-carbon organic acid.

8. **Formation of Acetyl Coenzyme A**: Pyruvate is further converted into acetyl coenzyme A, a two-carbon compound. This conversion marks the beginning of the TCA (Krebs) cycle.

9. **Continuation of the Process**: The TCA cycle continues the breakdown process, followed by the electron transport chain (ETC) and oxidative phosphorylation, which are the final stages of cellular respiration.

10. **Conclusion**: All the statements regarding respiration are true, highlighting its importance as a catabolic process that involves both physical and chemical changes, leading to energy production.

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