Bihar Board - Class 11 biology - Chapter 14: Respiration in Plants Handwritten Notes

Respiration in plants is the biochemical process by which plants break down glucose to release energy for cellular activities. This chapter define  the various types of their path and the significance of energy production for plant growth and metabolism.

Key Points

1. Basics of Plant Respiration

   • Plants break down carbohydrates (produced during photosynthesis) into simpler molecules to release energy in the form of ATP.
   • Occurs in all living cells, primarily in mitochondria.

2. Types of Respiration

   • Aerobic Respiration:
     • Requires oxygen.
     • Glucose is completely oxidized into carbon dioxide and water.
     • Produces a high amount of energy (38 ATP molecules per glucose molecule).
   • Anaerobic Respiration:
     • Occurs in the absence of oxygen.
     • Glucose is partially broken down into ethanol or lactic acid, releasing less energy.
     • Common in waterlogged conditions or during oxygen deficiency.

3. Stages of Aerobic Respiration

   • Glycolysis:
     • Occurs in the cytoplasm.
     • Glucose is converted into pyruvate, producing a small amount of ATP and NADH.
   • Krebs Cycle (Citric Acid Cycle):
     • Occurs in the mitochondrial matrix.
     • Pyruvate is completely oxidized, releasing CO₂, ATP, NADH, and FADH₂.
   • Electron Transport Chain (ETC):
     • Occurs in the inner mitochondrial membrane.
     • NADH and FADH₂ donate electrons to generate a proton gradient, driving the synthesis of ATP.

4. Fermentation (Anaerobic Pathway)

   • Involves the incomplete oxidation of glucose.
   • Produces ethanol and CO₂ in plants, with only 2 ATP molecules generated.

5. Respiratory Quotient (RQ)

   • Ratio of CO₂ evolved to O₂ consumed during respiration.
     • Carbohydrates: RQ = 1.
     • Fats: RQ < 1.
     • Proteins: RQ slightly greater than or less than 1, depending on conditions.

6. Factors Affecting Respiration

   • Temperature: Enzyme activity is temperature-dependent, with optimal activity at a specific range.
   • Oxygen Concentration: Influences aerobic respiration.
   • Water Availability: Essential for enzymatic activity.
   • Type of Substrate: Carbohydrates, fats, and proteins vary in energy release.

7. Significance of Respiration

   • Provides ATP, which powers various cellular activities like growth, reproduction, and repair.
   • Plays a role in the maintenance of plant metabolism and physiological processes.

Conclusion

Respiration in plants is an essential process that generates energy required for their growth and survival. By understanding the pathways and factors influencing respiration, we can appreciate the balance plants maintain between energy production and consumption, ensuring their role in sustaining life on Earth.

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