Assignment #3

1. What happens to radiant energy that reaches earth from the sun?
Radiant energy that reaches earth is called the greenhouse effect. The warmth from the sun heats the Earth’s surface, which then radiates the head energy absorbed outward. Most of this heat is radiated back into space, but some of the heat is retained in the atmosphere.

2. Name four greenhouse gasses in addition to water vapor
Methane, nitrous oxide, water vapor, and carbon dioxide.

3. How do water vapor and greenhouse gasses contribute to earth’s climate?
It works together to keep the Earth’s temperatures hospitable for life.

4. What are four sources of carbon dioxide?
Fossil fuels, coal, oil, natural gas.

5. Name three reservoirs for carbon dioxide in addition to the atmosphere
Living organisms, bodies of water, and soil.

6. What are fossil fuels? How are they made?
Fossil fuels are the buried remains of ancient plants and microorganisms that have been transformed by heat and pressure into coal, oil, and natural gases. These fuels are rich in carbon because plants remove carbon from the atmosphere during photosynthesis.

7. Where do plants get the carbon they need to build sugars?
Plants remove carbon from the atmosphere during photosynthesis. Consequently, plant structures are rich in organic carbon. Dead plant materials that are buried before they decompose, and thus before their carbon is released in the form of carbon dioxide, can produce fossil fuels.

8. Where do animals get the carbon they need to synthesize ATP?
Energy from the sunlight.

9. How has the amount of carbon dioxide in the atmosphere changed over the
past 100 years? What effect has this had on the planet’s overall climate?
The concentration of carbon dioxide in the atmosphere is much higher now then anytime in the past 400,000 years and that increased levels of carbon dioxide are correlated with increased temperatures. It is clear that when carbon dioxide levels increase, so do temperatures.

10. What is the difference in the chemical structure between ADP and ATP?
ADP is a nucleotide composed of adenine, a sugar, and two phosphate groups. Produced by the hydrolysis of the terminal phosphate bond of ATP. ATP is a nucleotide composed of adenine, the sugar ribose, and three phosphate groups that can be hydrolyzed to release energy.

11. How does ATP transfer energy to parts of a cell?
ATP acts like a coiled spring. ATP can be transferred to another molecule. Thus, ATP can energize other compounds through phosphorylation, which means that it transfers a phosphate to another molecule.
12. What is the difference between aerobic respiration and anaerobicrespiration?
Aerobic respiration is a cellular respiration that uses oxygen as the electron acceptor. Anaerobic respiration is a process of energy generation that uses molecules other than oxygen as electron acceptors.

13. Where do glycolysis, the citric acid cycle, chemiosmosis, and the light and
dark reactions of photosynthesis occur in cells?
It occurs in the Mitochondrion.

14. What are the final products of glycolysis? (don’t forget the energy carriers)
The final step is when an inner and outer membrane surrounds the mitochondria. The space between the two membranes is called the intermembrane space. The semifluid medium inside the mitochondrion is called the matrix.

15. What molecule enters the citric acid cycle? (hint: it’s not pyruvic acid)
ATP?

16. What are the final products of the citric acid cycle?
Removes electrons for use in producing ATP during the final step of cellular respiration. These electrons do not simply float around in a cell; this would damage the cell. Instead, they are carried by molecules called electron carriers.

17. Where does the electron transport chain get energy from to move H+ions
across the membrane into the inner membrane space?
Diffusion.

18. Why is oxygen needed for aerobic respiration?
When muscle cells run low on oxygen, they must get most of their ATP from glycolysis, the only step in the cellular respiration process that does not require oxygen. When glycolysis happens without aerobic respiration cells can run low on NAD+ because it is converted to NADH during glycolysis.

19. How is ATP generated via chemiosmosis? (be sure to explain the role of
ATP synthasein your answer)
During Chemiosis:ATP synthase (a transmembrane protein complex) caples movement of H+ ions down the protein

20. How many ATP are produced per NADH? Per FADH 2?
3 is produced per NADH. 2 is produced per FADH.

21. How many total ATP are produced from a single glucose molecule during
glycolysis followed by aerobic respiration?
2 ATP are interested early in the pathway and 2NADH and 4 ATP are generated for a net gain of 2NADH and 2ATP.

22. What part of proteins can be metabolized for energy?
Protein is broken down into component amino acids which are then used to synthesize new proteins. Most organisms can also break down proteins to supply energy. However this process only takes place when fats or carbohydrates are unavailable.

23. What part of lipids can be metabolized for energy?
The subunits of fats (glycerol and fatty acids) also go through the citric acid cycle and produce carbon dioxide, water and ATP. Most cells will break down fat only when carbohydrates supplies are depleted.

24. What is the purpose of fermentation? What would happen to cells if they
were somehow prevented from doing it?
Fermentation is to regenerate NAD+. No usable energy is produced by fermentation simply recyles NAD+. Fermentation cannot be used for very long because of its by products of this reaction leads to the build up of a compond called latic acid. Latic Acid is transported to the liver where calls use oxygen ro convert it back to pyruvic acid.

25. What are stomata? What type of cells make them up?
Stomata are adjustable microscopic pores found on the surface of leaves that allow for gas exchanges.

26. Where does the energy come from for the light-dependent reactions of
photosynthesis? Where in chloroplasts do these reactions occur?
Light dependant reactions of photosynthesis occur in the gamma via proteins embedded in the thylakoid membrane. During the light reactions of photosynthesis sunlight strikes chlorphyll molecules located in the thylakoid membrance exciting electrons that then move to a more higher energy level.

27. How do the energy carrier molecules synthesized during the light-dependent
reactions of photosynthesis compare to those synthesized during cellular
respiration?

The main function of cellular respiration is to convert the energy stored in chemical bonds od food into energy cells can use. Photosynthesis removes carbon dioxide from the atmposphere and use it to make sugars and other macromolecules by the process of photosynthesis. Through this process they release oxygen into the atmosphere.

28. Where in chloroplasts are glucose molecules synthesized? What process is
responsible for their synthesis?
Chloroplasts synthesize glucose molecules in the thylakoids, the large amount of membrane provides more surface area upon which some of the reactions of photosynthesis can occur. Light reactions and the Calvin Cycle are responsible for the synthesis.

29. Why is water necessary for photosynthesis? Why is carbon dioxide
necessary? Why is sunlight necessary?
With out the presence of sunlight we would not be able to perfomr the Calivin cycle. Light is transfered to the chloryphyll and becomes chemical energy. When sunlight strike the chloryphyll it becomes more excited and moves to a higher energy level. During the light reactions oxygen is produced when water is present.


30. How are rubisco and oxaloacetate similar?
Rubisco the enzyme that catalyzes the first step in the Calvin cycle of photosynthesis. A four-carbon molecule found in mitochondria that condenses with acetyl conenzyme A to form citrate in the first reaction of the citric acid cydle. Oxaloacetate must be constantly regenerated in order for the citric acid cycle and the electron transport chain to continue.

31. What is transpiration?
Water that can move out of the plant through the stomatal opening.

32. Which types of plants are most vulnerable to photorespiration? Why?
Photorespiration is the closing of the stomal openings to prevent water loss, thus C3 is the most vulnerable.

33. Why are C 3plants better adapted to cool, shady environments while C4
plants are better adapted to hot, sunny environments?
Enzymes used in C4 photosynthesis are also more sensitive to cold temperatures then the enzymes of the calvin cycle.
Rising temperatures can reduce the rate of photosynthesis because on hot days plants close their stoma to reduce the loss of water. C4 photosynthesis carries a cost-C3 plants require 3ATP molecules to convert 1 molecule of carbon dioxide into sugar but C4 plants require 5 molecules of ATP. Thus C3 plants have an advantage in certain enviromental situations (cool and shady) and C4 plants in (hot and sunny)
34. Why is growth limited in CAM plants?
Growth is limited in CAM plants because the amount of carbon dioxide stored in acid during the night is limited.

35. How does deforestation contribute to global warming? Deforestration is the process that clears forests for farmers, loggingand expanding human settlements. Cutting down trees directly links to the increase of carbon dioxide within the atmosphere.
36. What role does the United States play in global warming? The United States produces close to 1/4 of the carbon dioxide emitted by fossil fuel burning, The per capita emissions rate of carbon dioxide for americans is TWICE that of the Japenese or Germans , three times that of the global average, four times that of Sweeden, and 20 times that of the average Indian.