Respiration Notes: Aerobic, Anaerobic and Respiratory Quotient | PDF

PLB 203 Note Dr. Sherif B. Adeyemi (Not for sale) RESPIRATION Respiration is a vital process which occurs in all living cells of the plant but the most actively respiring regions are growing regions like flo...

PLB 203 Note Dr. Sherif B. Adeyemi (Not for sale) RESPIRATION Respiration is a vital process which occurs in all living cells of the plant but the most actively respiring regions are growing regions like floral and vegetative buds, germinating seedlings, stems and root apices. Respiration may be called a process which includes intake of O2 and chemically brings about the oxidation and decomposition of organic compounds with the release of energy. During normal conditions, the process involves the liberation of CO2, absorption of O2 and conversion of potential energy into kinetic energy. The overall respiration process may be presented as; C6H12O6 + 6O2 6CO2 + 6H2O + ENERGY In respiration, plants convert the sugars (photosynthates) back into energy for growth and other life processes (metabolic processes). Respiration is a complex process which includes; a. Absorption of O2 --- conversion of CHO (complex) to CO2 and H2O (simpler substance) i.e. oxidation of food b. Release of energy--- a part of which is utilized in various vital processes and the rest may be lost in the form of heat c. Formation of intermediate products playing different roles in metabolism d. Liberation of CO2 and water----loss in weight of plants as a result of oxidation IMPORTANCE OF RESPIRATION 1. It releases energy which is consumed in various metabolic processes essential for plants life and activates cell division 2. It brings about the formation of other necessary compounds participating as important cell constituents 3. It converts insoluble food into soluble forms 4. It liberates CO2 and plays a part actively in maintaining the balance of carbon cycle in nature 5. it converts stored energy (PE) into usable form (KE). 1 PLB 203 Note Dr. Sherif B. Adeyemi (Not for sale) RESPIRATORY QUOTIENT (RQ) This is defined as the rate between the volume of CO2 given out and the oxygen taken in simultaneously by a given weight of the tissue in a given period of time at standard temperature and pressure. 𝑉𝑂𝐿𝑈𝑀𝐸 𝑂𝐹 𝐶𝑂2 𝐸𝑉𝑂𝐿𝑉𝐸𝐷 RQ = 𝑉𝑂𝐿𝑈𝑀𝐸 𝑂𝐹 𝐶𝑂2 𝐴𝐵𝑆𝑂𝑅𝐵𝐸𝐷 The respiratory quotient depends upon the type of respiratory substrate used during respiration. For instance, when CHO are used as substrates and are completely oxidized, the RQ will be 1 because equal amounts of CO2 and O2 are evolved and consumed respectively C6H12O6 + 6O2 6CO2 + 6H2O + ENERGY 6CO2 RQ = = 1.0 6O2 When fats are used in respiration as substrate, the RQ is less than 1 2 (C51H98O6) + 145O2 102CO2 + 98H2O + ENERGY 102CO2 RQ = = 0.7 (