Set aside. 3.2. Immerse strips in 1% solution of ascorbic acid in an open petri plate. Set aside. 3.3. Boil water in a 250-ml beaker. Place strips of apple/potato and cucumber/tu rnip in boiling water for 3 minutes and then with the use of forceps, transfer the strips in an open petri plate. Set aside. 3.4. Get 2 test tubes and add 6 ml of 3% guaiacol. Place strips of fruit in one test tube and strips of vegetable in another test tube. Set aside. 3.5. Place strips in boiling water for 3 minutes. Use boiled water in # 3.3. Then, put in a test tube with 6 ml of 3% guaiacol. Set aside 4. After the treatments, allow the set- ups to stand for 20 minutes. Record the results in Table 5 of your worksheet. 5. Additional tests . Certain fruits and vegetables do not have the enzyme systems which are necessary for oxidations that cause the browning observed above. 6. Cut 6 strips more of cucumber. Expose 3 strips under condition 3.1 and 3 strips under condition 3.4. However, this time, add 10 drops of 3% hydrogen peroxide to the strips under both conditions. 7. Record your results. The peroxide acts as a source of oxygen for enzyme systems in these tissues. E2. Catalase 1. Get 2 test tubes and label A and B. Place 5 ml of 3% hydrogen peroxide in each tube. 2. Cut 6 strips (2 cm long, 0.5 cm wide and 0.5 cm thick) of freshly peeled potato tuber. 3. Place 3 freshly prepared strips in tube A. Boil the 3 remaining strips for 3 minutes and place these in tube B. 4. Observe the reaction after 10 minutes. References 1. Balbach, M. and L. C. Bliss. 1991. A Laboratory Manual for Botany. 7th edition. Saunders College Publishing. Orlando, Florida. pp. 181-189 2. Barbour, M. G., B. A. Bonner and G. J. Breckon. 1975. Botany. A Laboratory Manual. 5th edition. John Wiley and Sons, Inc. New York. pp. 89-93. 3. Department of Botany Faculty Staff. 1971. General Botany Laboratory Manual. Department of Botany, University of the Philippines. Diliman, Quezon City. pp. 42-44. 4. Moore, R., W. D. Clark, K. R. Stern and D. Vodopich. 1995. Botany. Wm. C. Brown 4
Publishers. Dubuque, Indiana. pp. 110-129. 5
Student’s Name ___________________________ Date Performed __________ LBYBIO______ Section ________ Date Submitted __________ Professor’s Name__________________________ WORKSHEET # 7 CELLULAR RESPIRATION A. Oxygen consumption by germinating seeds Table 1. Effect of pyrogallol solution on germinating corn seeds. Set-up: Observations (Number and condition of seeds that germinated) 1. Seeds + water 2. Seeds + water + pyrogallol solution Questions: 1. Did both batches of seed germinate? 2. Which bottle shows more evidence of seed germination? 3. What accounts for the difference in the germination of the seeds?
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