Download HW #23 KEY 1. Adenosine triphosphate is the energy currency of

HW #23
KEY
1. Adenosine triphosphate is the energy currency of the cell.
2. The study of the flow and transformation of energy is called thermodynamics.
3. Energy can exist in many forms.
4. Chemical reactions that convert energy within a cell are referred to as metabolism.
5. Light energy is converted into chemical energy during the process of photosynthesis.
6. Which is not a characteristic of energy? D – changes spontaneously from disorder to order
7. Which organism depends on an external source of organic compounds? B – Heterotroph
8. Which part of this food chain provides energy to just one other part? D – the photoautotroph
9. What do cells store and release as the main source of chemical energy? A – ATP
10. How do autotrophs and heterotrophs differ in the way in which they obtain energy? Autotrophs get energy
by absorbing light energy from the sun, whereas heterotrophs get energy from the chemical energy stored in
food.
12. Describe how energy is released from ATP. Energy is released from ATP when it is broken down
(hydrolyzed) into ADP and a phosphate group.
13. Relate anabolic and catabolic reactions. Create an analogy for the relationship between photosynthesis and
cellular respiration. Anabolic pathways store energy by building molecules. Catabolic pathways release energy
by breaking down molecules.
14. The location of the light reactions – thylakoid
15. A stack of thylakoids – granum
16. A colored molecule that absorbs light – pigment
17. A process in which energy is stored in organic molecules – Calvin cycle
18. What waste product of photosynthesis is released to the environment? C – oxygen
19. Which is the internal membrane of the chloroplast that is organized into flattened membranous sacs? A –
thylakoids
20. Of which wavelength of light do carotenoids absorb the greatest percentage? B – 500
21. Which supplies energy used to synthesize carbohydrates during the Calvin cycle? B – ATP and NADPH
22. Summarize the phases of photosynthesis. Describe where each phase occurs in the chloroplast. Lightdependent reactions – sunlight is absorbed by chlorophyll, producing ATP and NADPH. Light-independent
reactions (or Calvin cycle) – ATP and NADPH are used to fuel the conversion of carbon dioxide into glucose.
23. Why is hydrogen ion generation essential for ATP production during photosynthesis? Hydrogen ion
generation is essential for ATP production because it provides energy for conversion of ADP to ATP by ATP
synthase.
24. Explain why the Calvin cycle depends on light reactions. The Calvin cycle depends on light-dependent
reactions to provide the energy (ATP and NADPH) needed for glucose production.
27. Describe two alternative photosynthesis pathways found in plants. Suggest how these adaptations might
help plants. C4 pathway – fixes carbon dioxide into four-carbon molecules instead of three-carbon molecules in
the Calvin cycle; plants have modifications in arrangements of leaf cells; helps plants maintain photosynthesis
while minimizing water loss. CAM photosynthesis: carbon dioxide enters only at night when carbon dioxide is
fixed into organic compounds; during the day, CO2 is released from these compounds and enters the Calvin
cycle; allows for sufficient CO2 uptake while minimizing water loss. Both pathways help plants survive extreme
climates.
28. Krebs cycle – Pyruvate is broken down into carbon dioxide during the Krebs cycle.
29. Anaerobic process - Anaerobic processes occur in the absence of oxygen.
30. Fermentation – The two types of fermentation are lactic-acid fermentation and alcohol fermentation.
31. Aerobic – Oxygen is required for aerobic processes.
32. Glycolysis – Glucose is broken down during the process of glycolysis.
33. Which organelle is illustrated in the figure? B – mitochondrion
34. Which process does not occur in the organelle illustrated above? A – glycolysis
35. Which is not a stage of cellular respiration? D – lactic acid fermentation
36. What is produced when the electrons leave the electron transport chain in cellular respiration and bind to the
final electron acceptor for the chain? A – H2O
37. In which molecule is most of the energy of glucose stored at the end of glycolysis? C – ATP
40. Why do your muscles hurt for some time after a large amount of strenuous exercise? Muscles are sore after
exercise because lactic acid is produced by the fermentation of pyruvate, which occurs when oxygen levels are
low.
41. The end products of cellular respiration are CO2 and H2O. Where do the oxygen atoms in the CO2 originate?
Where does the oxygen atom in H2O originate? The oxygen atoms in carbon dioxide come from glucose, and
the oxygen in water comes from the atmosphere.
42. What is the advantage of aerobic metabolism over anaerobic metabolism in energy production in living
organisms? Aerobic metabolism is more efficient in forming ATP because the Krebs cycle and the electron
transport chain (both of which require oxygen) produce 32 molecules of ATP. Only 2 molecules of ATP are
produced by glycolysis.
44. What are the chemical equations for photosynthesis and cellular respiration? Analyze the relationship
between photosynthesis and cellular respiration using the equations for both processes. Photosynthesis converts
CO2 and H2O to sugars; cellular respiration converts those sugars into CO2 and H2O.
46. What was the effect of cadmium on leaf size, chlorophyll content, and photosynthesis rate? Increasing
concentrations of cadmium decreased leaf size, chlorophyll content, and the rate of photosynthesis.
47. At what concentration of cadmium was the largest effect on leaf size observed? On chlorophyll content? On
photosynthesis rate? The highest concentration had the greatest effect on all three variables tested.
48. Predict the effects on cellular respiration if an animal eats contaminated tomatoes. Since the light-dependent
reaction and the electron transport chain are very similar, cellular respiration may decrease.