Review Sheet
AP Biology
Exam 4 will cover:
Chapter 7: Material from the test
Chapter 8: ALL
Chapter 8:
ENERGY and the laws that govern its transfer
1. What is energy?
2. Describe the two major types of energy and give examples.
3. Identify and describe the two forms of potential energy (PE) discussed in class. You
should be able to explain the connection between the four forces of the universe and
energy.
4. What gives a substance like glucose energy?
5. Describe the first law of thermodynamics. Why can’t I create energy (why can’t I give
something the ability to accelerate without losing some of my own energy)?
7. Describe all the energy transfers that occur starting with you standing next to a tennis
ball on the floor, you pick up the ball, you drop it, it bounces a few times and eventually
stops. Make sure you describe where the energy started and where it went throughout
(follow the ability to accelerate).
8. What does the 1st law of thermodynamics tell us about the total energy in the universe?
9. Describe the second law of thermodynamics and the implications of this law in terms
of entropy.
10. Explain why if I throw a ball to you, 100% of the energy that I put into the ball is not
transferred to you. Where does the energy go since it can’t be destroyed?
11. Explain why your shoes, clothes, ipod, cell phone, computer, dishwasher, oven,
refridgerator, car, wii, xbox and everything else will eventually break, in terms of the 2nd
law. Do not just say that things get more disordered with every energy transfer. Why does
this happen? Define order.
12. What is order? Disorder? Why does matter tend to “disorder” with energy transfers in
terms of probability?
13. What does the 2nd law tell us about our own life? What will happen to the DNA in our
cells over time regardless of how well our enzymes are at repairing it?
14. The 2nd law also dictates that energy goes from concentrated to dispersed. Likewise, it
goes from useful to less useful. Give an example of this in your life. Be very specific.
15. How are we able to generate the desired or ordered state if the universe is always
getting more disordered? What has to happen whenever order (a particular arrangement
of matter) is generated or forced like keeping our atoms in the arrangement that they are
to live?
16. In order for your proteins to keep yourself ordered, you have to take in food. Some of
this food will be burned in cell respiration and the energy transferred into ATP as
discussed in class. Why do we need to keep eating in order to maintain order in our
bodies? For all the order your body maintains, you must be generating more disorder
around you. Explain how this is happening. Where is the disorder? How is your body
generating disorder around you as you sit here and read this?
17. Why can’t we win? Why can’t we continue to maintain the ordered state and live
forever?
18. If you wanted to preserve something that you love like an old doll, how would you do
this and why? Hint: How do we store the declaration of independence?
19. What is the energy source for 99.9% of life on this planet? Basically, if I track back
my body’s ability to accelerate, where did this ability come from? Explain in general
terms how you got this ability form that source. Go back to the forces.
20. We concluded in class that we are constantly fighting the 2nd law of thermodynamics
whether it is fixing items that break, buying new items to replace broken ones, or trying
to prevent items from breaking like putting those rubber cases around ipods and iphones
so that the rubber cases take the energy transfers and get disordered instead of your
phone, or painting your house every so many years, etc... Our bodies are doing the same
thing: our proteins are constantly repairing their homes (cells), and certain cells that have
too much damage and are thrown out (apoptosis), you have enzymes that eliminate toxic
chemicals to prevent damage, and your cells will divide to replace those that have been
lost. All of this repair and maintenance requires matter to be accelerated in a specific
manner and therefore requires energy (ATP). The point of saying this is that it appears
that the 2nd law is terrible, but there is a silver lining. Explain the upside.
21. Why is reproduction so important in light of the 2nd law of thermodynamics?
22. Compare and contrast endergonic to exergonic reactions. Under which would you put
the overall reaction of photosynthesis? Cell respiration? Explain both.
23. Compare the PE of the reactants to the products for the two reactions (endergonic and
exergonic). For example, ATP  ADP + Pi ; This reaction is exergonic as the phosphate
on ATP has the ability to accelerate (you should know why). Therefore, energy is lost to
somewhere. Where does the energy (ability to accelerate) go?
24. Define Gibbs Free Energy (G).
25. Define G.
25. What sign does G have when describing an exergonic process? What about an
endergonic process? Explain.
26. What two variables must be measured to determine free energy changes in systems?
Explain how these relate to G.
27. If H is negative and S is positive, what does this tell you? Explain why.
28. If H is positive and S is negative, what does this tell you? Explain why.
29. You should memorize the G for cell resp, ATP synthesis, ATP hydrolysis and
photosynthesis.
30. Describe what is meant by energy coupling and give an example in terms of G.
31. What happens when you reverse an endergonic reaction like putting a phosphate onto
ADP? What type of reaction do you get? What happens to G when you reverse a
reaction? Why?
32. Explain the following energy coupling examples (identify the exergonic process and
the endergonic process): 1. lifting a book off the ground, 2. Dropping the book, 3. Water
moving through a dam spinning turbines, 4. A gas powered engine, 5. Active transport
using a transporter protein like in figure 5.18, 6. Electrons moving from glucose to
oxygen allowing a phosphate to be placed on ADP to make ATP.
33. Explain fire (burning wood). Follow the energy flow. How does this compare to cell
resp?
34. Be able to draw the structure of ATP.
35. In class we said that one glucose can be used to make 36 or 38 ATP molecules.
Compare the amount of energy in the glucose to that in the 36 ATP in terms of G. You
should be able to calculate this on the test. Explain the discrepancy.
36. Why use ATP? Why not just use glucose or amino acids or triglycerides or sucrose or
fatty acids directly as a source of energy?
37. How efficient is the production of ATP from glucose? What law of thermodynamics
does this observation support? Explain.
38. Which yields more ATP, glucose or triglycerides? Explain why.
39. After the third phosphate of ATP has been transferred to a protein, causing a
conformational change, what is the fate of the resulting ADP?
40. How many ATP are used per second per cell? 10,000,000 per cell per second on
average. That means this many are made and used per second!
41. Identify at least five endergonic reactions in the cell that must be powered using the
exergonic reaction of ATP hydrolysis.
42. Why do we breathe in air for molecular oxygen (O2)?
43. Describe the three major fates of the food that you eat. Which are exergonic and
which are endergonic? Which are catabolic and which are anabolic?
44. Are glucose and triglycerides the only molecules you can use as an energy source?
Explain.
45. In class we determined two major problems with chemical reactions in terms of life.
First is that exergonic reactions typically happen way too __________________. The
second is that the desired reaction may not be the reaction that occurs. We said that
glucose + glucose + glucose… typically results in the formation of glycogen in animal
muscle and liver cells, but it could also become cellulose in plants. It of course depends
on the glycosidic linkage that is formed between carbon 1 and carbon 4 of the glucose
molecules. Therefore, to make sure the desired reaction occurs faster than the undesired
ones, a cells needs…
HOW ENZYMES WORK
46. What is an enzyme?
47. Explain why enzymes CANNOT, by themselves, catalyze endergonic reactions like
putting a phosphate onto ADP. What would this enzyme need to allow this reaction to be
catalyzed?
48. What reaction does carbonic anhydrase catalyze? What is the rate per enzyme? What
cofactor does this enzyme require? How is this cofactor held in place? What is the
significance of this cofactor? Know the reaction mechanism.
49. What is activation energy? If you push a boulder off a cliff and it falls 300 feet
smashing a car below, what was the activation energy? Explain activation energy.
50. Explain how enzymes lower the activation energy of a reaction. Be specific. There
are four key points. Identify the three that are always present in all enzymes.
51. Be able to graph a reactions progress over time from products to reactants in terms of
energy for both exergonic and endergonic reactions. You should be able to label
everything like Ea, G, etc…
52. Describe how an enzyme works starting with the binding of substrate(s) to the release
of product(s). Use the detail general overview of enzyme catalysis review slide. Be sure
to explain how they lower activation energy. This is extremely important!
53. Compare the lock and key to the induced fit model of enzyme catalysis. Which is the
current model? Why does this one make more sense? (You should know the hexokinase
example).
54. Construction workers use hammers in order to catalyze the specific reaction of
hammering nails into wood. This is analogous to what in proteins?
55. Describe the two general types of cofactors and give examples of each. Are cofactors
only used by enzymes? Explain.
56. Discuss the structure and function of hemoglobin. Where is it located? How many per
cell? Etc… What cofactor does hemoglobin require to function? Explain why if you do
not get enough iron in your diet, you will become anemic (have a reduced ability to carry
oxygen in your blood) on the molecular level.
57. When you eat, you are basically eating for monomers to build with (biosynthesis) and
to burn for energy. However, you also need the so-called vitamins and minerals. What are
these? How do they relate to protein cofactors?
58. Aside from heme and Zinc, we discussed two other cofactors, NAD+ and FAD. What
vitamins are required to synthesize these cofactors? Describe the structure of NAD+ and
FAD. You should know the full name of each. Describe how their names are related to
their structures. Describe the function of these two cofactors.
59. What is an enzymatic reaction rate? What factors affect reaction rates? You should
know all five factors discussed. I could ask you to graph for example the rate of a
reaction as I increase/decrease substrate concentration, enzyme concentration,
temperature, pH, salt, etc…Make sure you can explain why this is happening logically.
60. Sometimes we revert back to illogical reasoning and think that all enzymes function
best at body temperature and pH 7. Explain why this is far from the truth.
61. What would you hypothesize the optimal salt (NaCl) concentration to be for a human
protein? Why? What happens if salt gets too high? Too low? Answer the same questions
for temperature and pH.
61. Explain why, logically, enzymes or enzyme pathways need to be regulated (need to
be turned on and off), and why this only needs to occur at certain steps and not all of
them. Give examples.
62. Build a tree diagram showing the relationship between competitive inhibitors, noncompetitive inhibitors, allosteric inhibition, and non-allosteric inhibition.
63. Describe how allosteric regulation works and discuss the PFK example.
64. Describe the other methods of enzyme inhibition/activation discussed in class.
65. Explain how enzyme inhibition is taken advantage of by humans to treat disease.
Give a few examples.
66. If you wanted to design an inhibitor of an enzyme of a bacterium that causes a certain
disease and you wanted it to be a competitive inhibitor, what might you try first (what
might you base it on)?
66.5. Describe the various ways that protein can be activated.
67. Explain how enzymes are typically activated during signal transduction and signal
amplification. What is signal amplification and how does it work?
68. Explain how phosphorylation can be used to both inhibit and activate different
enzymes.
69. What is the name given to the type of enzyme that catalyzes phosphorylation.
70. What is meant by an enzyme pathway? How are enzyme pathways typically
regulated?
71. What type of reaction do dehyrogenases typically catalyze and what cofactors are
typically involved?
72. Compare negative feedback to positive feedback and give examples of both. Which is
more stable (which would you use to maintain homeostasis of some substance?). Explain
why.
73. Describe how negative feedback and allosteric regulation come together at PFK in
glycolysis.
74. How many different reactions does a single enzyme typically catalyze? What about
XDH?
STUDY WELL