Name _____________________________ Date _______________Essay Test: Cellular Energy

Chapters 8 – 10Complete the answers to the best of your ability. You may discuss these questions with your classmates and with me, but not with any other science teachers. You may research the answers in the textbook and on the Internet. However, in the end, your answer must be wholly your own. It must be written in your own words. You cannot copy or paraphrase from any source. EVERY STUDENT MUST CRAFT HIS OR HER OWN ANSWER AND MUST HAVE A COMPLETELY UNIQUELY WORDED ANSWER FOR EACH QUESTION. I will hold you to a very strict standard on this — any suspicion of plagiarism will cause each student involved to LOSE FULL CREDIT. This exam MUST be TYPED at 1.5 SPACING. It is due Tuesday, November 30, 2010 at 5:00pm. You may hand in the document in hard copy during the school day on Tuesday or e-mail it to me in either Microsoft Word or Adobe Acrobat PDF format on Tuesday. No other software is acceptable; Microsoft Works is not acceptable. Concise answers — short and to the point — are appreciated. More words do not make your answer more right.

1. Amylase is the enzyme that breaks down starch to sugars (glucose and maltose) in humans (and in many other organisms). Students studied this reaction in a lab activity by mixing amylase and starch in a test tube.a.) The students found that the reaction rate increased as the test tube was heated from 0°C to 37°C. Explain why this occurs. (2)b.) But the students then found that the reaction rate decreased as the test tube was heated from 40°C to 90°C, Explain why this occurs. (2)c.) And finally students found that the reaction ceased when the test tube was heated to 100°C, Explain why this occurs. (1)d.) Give an example of specific data that students could measure in this experiment to determine the rate of amylase activity. Suggest a way that this variable could be measured. (1)

2. The oxidation of wood (fire) and the oxidation of glucose (respiration) are basically the same exergonic reaction. However the amount of heat released by fire would destroy a cell. Explain how a cell manages to harvest the energy stored in glucose and still maintain internal temperatures conducive to life. (5)

3. To efficiently manage metabolism, cells need to precisely coordinate and regulate a complex web of chemical reactions.a.) Explain why cells need to efficiently manage metabolic pathways and why it is an evolutionary advantage to do so. (3)b.) Feedback inhibition is a common regulatory mechanism. Describe what feedback inhibition is and explain why it is an efficient system for regulating biochemical pathways. (2)

4. ATP is the “energy currency” of the cell.a.) Explain why ATP functions well in this role. (2)b.) Explain why ATP is only good for short-term energy storage. (2)c.) Explain what a cell uses for longer term energy storage and explain why. (2)

5. Acetyl-CoA is a key molecule in both oxidative cellular respiration and the synthesis of fat (and other large molecules). Explain how the cell can regulate its metabolism if the same molecule is used in both energy production and biosynthesis? (5)6. Scientists consider glycolysis to be one of the earliest biochemical processes to evolve in the first living cells. Describe the evidence that supports this. (5)

7. It is often said that the enzyme ATP synthase works like a water wheel turbine. Explain the details of this analogy — what flows, what turns, and what work is done? (5)

Name _____________________________ Date _______________8. Why do we breathe in oxygen and why do we die when we can’t? (5)

9. In 2005, 29 children died in the Philippines from cyanide poisoning by eating improperly prepared cassava desserts sold at a local fair. In 1945, Adolph Hitler committed suicide by ingesting cyanide salts. Explain how cyanide functions as a metabolic poison. Be specific! (5)

10. In biological systems, structure and function are related and membranes are important structural features of cells. a). Describe the specific role of membrane structure in the synthesis of ATP in either cellular respiration or photosynthesis. (3)b.) Describe the structure of a mitochondria and a chloroplast. Explain in detail how the structure of these organelles is important to their functions.(3)

11. Compare the overall process of cellular respiration and photosynthesis with regard to their redox reactions. Be specific.(6)

12. Sunlight can be called “the ultimate fuel source for all communities on Earth”. a.) What type of energy is sunlight? (1) b.) What is wavelength, λ, a measure of? What are the units? (1)c.) What colors of light does the chlorophyll a pigment absorb? What colors of light does chlorophyll b absorb and reflect? What colors of light do the carotenoids absorb and reflect? (2)d.) Why do plants look green? (1) e.) Describe the significance of the graph at the right.

13.What happens when a chlorophyll molecule absorbs a photon of light? Compare isolated chlorophyll with chlorophyll in a chloroplast. What is fluorescence? (4)

14.Compare/contrast PSI and PSII. How are they similar? different? (4)

15.What is the limitation of C3 plants in hot, dry areas? What is photorespiration? For both a C3 and a C4 plant, trace the path of a carbon dioxide molecule from the point at which it enters a plant to its incorporation into a glucose molecule. Include leaf anatomy and biochemical pathways in your discussion of each type of plant. (6)

16.The rate of photosynthesis may very with changes that occur in environmental temperature, wavelength of light, and light intensity. Using a photosynthetic organism of your choice, choose only ONE of the three variables (temperature, wavelength of light, or light intensity) and for this variablea. Design a scientific experiment to determine the effect of the variable on the rate of photosynthesis for the organism; (2)b. Explain how you would measure the rate of photosynthesis in your experiment;

Name _____________________________ Date _______________c. Describe the results you would expect. Explain why you would expect those results. (2)