Respiration in Plants

Respiration in Plants Respiration is a series of chemical reactions, in each reaction stage very sensitive to temperature. Temperature affects the rate of chemical reactions, both organic chemistry and inorganic chemistry. This situation also applies to reactions catalyzed by enzymes, but is limited only to a certain temperature, because at high temperatures the enzyme becomes inactive. Most enzymes begin to become inactive at a temperature of approximately 50OC. An increase in temperature has two consequences opposite to the enzymatic reaction rate, namely: 1) the reaction is accelerated and 2) the reaction is inhibited (enzyme inactivity is accelerated). So under certain circumstances there is an optimal temperature for a reaction. The optimal temperature is not certain, because it is influenced by the length of observation time. If the observation time is very short, then the enzyme does not need to work long and the high temperature will cause the reaction to be accelerated. However, if the observation time is long, the high temperature will cause some of the enzymes to be damaged, thereby reducing the concentration of active enzymes. Thus the overall reaction rate decreases. In this experiment several temperatures below the enzyme inactivation point will be tried, and the respiration rate is determined by measuring the amount of CO2resulting from. Tissue respiration rate is directly influenced by two environmental factors, namely oxygen concentration and temperature. Oxygen gas is absorbed from the atmosphere, reduced to water by hydrogen released from the respiratory substrate. If the rate of oxygen diffusion into the cell is disturbed, the respiration rate will decrease because the release of hydrogen from the substrate does not occur. Plants will suffocate if they lack oxygen. Roots die if the soil is flooded or without aeration, and as a result plant development is hampered. Respiration is one of the most important processes in living cells. In this process free energy (ATP and NADH) is formed which is needed in the process of cell synthesis and intermediate compounds which are substrates for the synthesis of other compounds (amino acids, proteins, fats, etc.). Therefore the rate of tissue respiration can provide an idea of the level of metabolic activity in that tissue. Respiration rate is determined by measuring the amount of CO2formed and O gas2absorbed per unit fresh (dry) weight of tissue per unit time. Experiment a. Effect of Temperature on the Speed of Aerobic Respiration Objective: To determine the effect of temperature on the aerobic respiration rate of sprouts. Materials and tools: Plant Materials : 4 day old plant sprouts Tools : Bottles, aluminum foil, gauze, thread, labels, rubber bands, and CO2meters Ways of working: 1. Weigh 10 g of sprouts, wrap them in gauze and tie the ends with the thread left long. 2. Insert it into the bottle in a hanging position, by tying the end of the thread to the lip of the bottle. 3. Cover with aluminum foil and tie with a rubber band. 4. Make a control with bottles without sprouts, placed at room temperature. 5. Label each bottle, and place it in the refrigerator (5oC), room (27oC), and incubator (40oC). 6. After one hour measure the CO level2produced using a CO device2meters. 7. Respiration rate can be calculated Experiment b. Determination of Respiration Speed of Germinating Seeds Objective: Determine the respiration rate of germinating seeds using the titration method. Materials and tools: Plant material : Green bean seeds are germinated for 1-5 days (each different age groups of sprouts) Chemical material : NaOH 0.2 N, HCl 0.1 N, pnolphthalein indicator, Tools : Bottle or Erlenmeyer with rubber cover, Erlenmeyer 125/250 mL, gauze, thread, scissors, burette and pipettel Ways of working: 1. Place 50 mL of 0.2 N NaOH in each of 5 bottles or flasks, and immediately close tightly using a rubber stopper. 2. Weigh 10 g of green bean sprouts according to the treatment for each group in gauze tied tightly with thread. Hang it inside the bottle with thread. 3. One of the NaOH bottles without seeds is used as a control 4. Label the bottles and place 25oC (room temperature) for 3-6 hours 5. After 3-6 hours, the seeds are removed from the bottle and the bottle is immediately closed again 6. Determine the amount of CO2released during respiration using the titration method: a. Pipette 10 mL of the solution in the bottle into the Erlenmeyer flask b. Add 3 drops of phenolphthalein indicator, then titrate with 0.1 N HCl until the color disappears c. Do the same thing with the control (bottle containing 0.2 N NaOH), subtract the value obtained from the first bottle from the value from the control bottle d. Perform a duplo titration on each flask. The value obtained shows the total amount of acid equivalent to CO2produced during respiration