AP Biology Practice Exam #3
Subunit #3: Cellular Energetics
_____1. Which form of energy is Not correctly associated with an example?
a) kinetic energy : fat molecules
b) kinetic energy : movement of muscles
c) chemical energy : glucose
d) potential energy : water held behind a dam
e) potential energy : ATP
_____2. Which Best describes the first law of thermodynamics?
a) Energy is not created nor destroyed, but it can change into matter.
b) Energy is not created nor destroyed, but it can change from one energy form to another.
c) Energy can be created from matter or used to produce matter.
d) Some useful energy is lost as heat whenever an energy transfer occurs.
e) Energy transfers are always 100% efficient in changing energy from one useful form to another.
_____3. Which Best describes the second law of thermodynamics?
a) Energy is not created nor destroyed, but it can change into matter.
b) Energy is not created nor destroyed, but it can change from one energy form to another.
c) Energy can be created from matter or used to produce matter.
d) Some useful energy is lost as heat whenever an energy transfer occurs.
e) Energy transfers are always 100% efficient in changing energy from one useful form to another.
_____4. Endergonic reactions
a) are always coupling reactions
b) have a negative change in free energy and occur spontaneously
c) can only occur if there is an input of energy
d) have products with less free energy than the reactants.
e) All of the above are correct.
_____5. The subunits from which ATP is made are
a) ADP and phosphate
b) FAD and NAD+
c) FAD and NADPH
d) ADP and FAD
e) ADP and NAD+
_____6. An enzyme is generally named by adding ____ to the end of the name of the _____.
a) "-ose". cell in which it is found
b) "-ase". cell in which it is found
c) "-ose". substrate
d) "-ase". substrate
e) "-ase". coenzyme
_____7. A coenzyme is
a) an ionic cofactor that interacts with an enzyme to allow it to work.
b) a protein cofactor that interacts with an enzyme to allow it to work.
c) a nonprotein organic cofactor that interacts with an enzyme to allow it to work.
d) an ionic cofactor that interacts with an enzyme to inhibit it.
e) a protein cofactor that interacts with an enzyme to inhibit it.
_____8. Consider this reaction. A + B à C + D + energy.
a) This reaction is exergonic.
b) An enzyme could still speed the reaction.
c) ATP is not needed to make the reaction go.
d) A and B are reactants; C and D are products.
e) All of these are correct.
Question 9 refers to the diagram below:
_____9. Which of the following is true about what is taking place in this reaction?
a) It is exergonic.
b) It is an anabolic reaction.
c) It requires the removal of a molecule of water.
d) It requires a net input of energy.
e) It forms two insoluble molecules.
_____10. An inhibitor that changes the overall shape and chemistry of an enzyme is known as a(n)
a) allosteric inhibitor b) competitive inhibitor c) steric inhibitor d) noncompetitive inhibitor e) None of the above.
_____11. The difference between NAD+ and NADP+ is that
a) only NAD production requires niacin in the diet.
b) one is an organic molecule and the other is inorganic because it contains phosphate.
c) one carries electrons to the electron transport system and the other carries them to synthetic reactions.
d) one is involved in cellular respiration and the other is involved in photosynthesis.
e) Both C and D are correct.
_____12. A student conducts an experiment to test the efficiency of a certain enzyme. Which of the
following protocols would probably Not result in a change in the enzyme's efficiency?
a) Bringing the temperature of the experimental setup from 20 degrees C to 50 degrees C.
b) Adding an acidic solution to the setup.
c) Adding more substrate but not enzyme.
d) Placing the substrate and enzyme in a container with double the capacity.
e) Adding enzyme but not substrate.
_____13. Sunlight arrives at a plant in units of light energy called
a) protons b) photons c) electrons d) wavelengths
_____14. Why are plants green?
a) They absorb only green wavelengths of light.
b) They absorb only yellow and blue wavelengths of light.
c) They reflect nearly all wavelengths of light.
d) They reflect green wavelengths of light.
e) They reflect yellow and blue wavelengths of light.
_____15. To what does the term stroma refer?
a) the double membrane of the chloroplasts
b) a flattened disk or sac in the chloroplast
c) a central fluid filled space in the chloroplast
d) the cytochrome system in the membranes of the thylakoids
e) a stack of thylakoid membrane structures
_____16. To what does the term grana refer?
a) the cytochrome system in the membranes of the thylakoids
b) a central fluid filled space in the chloroplast
c) a flattened disk or sac in the chloroplast
d) the double membrane of the chloroplasts
e) a stack of thylakoid membrane structures
Question 17 refers to the absorption spectrum for a newly discovered plant illustrated below:
_____17. According to the diagram, which wavelength of light is most effective for photosynthesis for this pigment?
a) red b) orange c) green d) blue e) violet
_____18. All of the following could reduce the yield of photosynthetic products EXCEPT
a) increased photorespiration
b) reduced carbon dioxide concentrations in the air spaces of the leaf
c) increased frequency of stomatal openings
d) fewer Calvin cycle enzymes
e) lower concentrations of carbon dioxide in the atmosphere
Questions 19-22 refer to molecules of the following substances:
a) Oxygen (02) b) NADP c) NAD d) FADH2 e) Cytochrome
_____19. The final electron acceptor for cellular respiration
_____20. A membrane-bound electron carrier found in the electron transport systems of both aerobic respiration and photosynthesis
_____21. An intermediate electron acceptor for oxidations that occur in both glycolysis and in Krebs cycle reactions
_____22. Coenzyme that transfers electrons from the Krebs cycle to the mitochondrial electron-transport chain at a lower energy level than that of electrons entering at the beginning of the chain
_____21. Which of these is most closely associated with the process of electron transport?
a) a stack of thylakoid membrane structures
b) a flattened disk or sac in the chloroplast
c) the double membrane of the chloroplasts
d) the cytochrome system in the membranes of the thylakoids
e) a central fluid filled space in the chloroplast
_____22. Which statement is Not true about the cyclic electron pathway?
a) It produces ATP.
b) It involves Photosystem I.
c) It produces NADPH.
d) It is believed to be the first of the two electron transport pathways to have developed.
_____23. Which statement is Not true about the noncyclic electron pathway?
a) It absorbs photons into Photosystem I.
b) It absorbs photons into Photosystem II.
c) It produces ATP.
d) It produces NADPH.
e) It produces carbohydrates through carbon dioxide fixation.
_____24. When the stomates in a leaf close, then
a) carbon dioxide in the air spaces in the leaf decreases.
b) oxygen in the air spaces in the leaf increases.
c) C3 plants carry on photorespiration. using oxygen and producing PGA and carbon dioxide.
d) all photosystems as well as photorespiration come to a halt.
e) A, B, and C are correct.
_____25. Which would be a CAM plant?
a) cactus b) corn c) rice d) wheat e) oak tree
Question 26 refers to the diagram below:
_____26. Which types of plants display this biochemical pathway?
a) CAM b) C4 c) C3 d) None of these e) All of these
_____27. Which of the following processes is carried out more efficiently by a C4 plant than by a C3 plant?
a) Transport of sugars b) Fixation of CO2 c) Photolysis d) Light absorption e) Chemiosmotic coupling
_____28. This process has as its products NADP+ and ADP, and sugar.
a) glycolysis b) chemiosmosis c) fermentation d) Calvin cycle e) photolysis
_____29. Which of the following photosynthetic reactions is known to occur in the thylakoid membrane?
a) carbon fixation b) light reactions c) dark reactions d) Calvin cycle e) transpiration
_____30. On a sunny day, the closing of stomata in plant leaves result in
a) a decrease in CO2 intake
b) a shift from C3 photosynthesis to C4 photosynthesis
c) an increase in transpiration
d) an increase in the concentration of CO2 in mesophyll cells
e) an increase in the rate of production of starch
_____31. The products of the light reactions in photosynthesis are
a) oxygen and NADP+ b) water and NADPH c) oxygen and NADPH d) water and oxygen e) oxygen and NAD+
_____32. If 6 molecules of oxygen are released during photosynthesis, how many molecules of
carbon dioxide would be fixed?
a) 1 b) 3 c) 6 d) 12 e) 24
_____33. The O2 released during photosynthesis comes from
a) C6H12O6 b) RuBP (RuDP) c) NADPH d) H2O e) CO2
_____34. The cyclic pathway of photosynthesis occurs because
a) The chloroplasts need to regenerate NAD+.
b) The Calvin cycle uses more ATP than NADPH.
c) It can occur in regions lacking light.
d) It is more efficient way to produce oxygen.
e) It is a more efficient way to produce the NADPH needed for the Calvin cycle.
_____35. Carbohydrate-synthesizing reactions of photosynthesis directly require
a) Chlorophyll and CO2 b) O2 and H2O c) darkness d) light e) products of the light reactions
_____36. Which of the following is an important difference between light-dependent and light-independent reactions of photosynthesis?
a) The light-dependent reactions produce ATP and NADPH; the light-independent reactions use energy stored
in ATP and NADPH.
b) The light-dependent reactions occur in the cytoplasm, the light-independent reactions occur in the
chloroplasts.
c) The light-dependent reactions depend on the presence of both photosystems I and II; the light-independent
reactions require only photosystem I.
d) The light-dependent reactions utilize CO2 and H2O; the light-independent reactions produce CO2 and H2O.
e) The light-dependent reactions occur only during the day, the light-independent reactions occur only during
the night.
_____37. The carbon that makes up organic molecules in plants is derived directly from
a) combustion of fuels
b) carbon fixed in photosynthesis
c) carbon dioxide produced in photosynthesis
d) carbon in the lithosphere
e) coal mines
_____38. The light independent cycle of photosynthesis receives energy rich molecules from which of the following?
a) ATP from respiration
b) O2 and H2O from the light reaction
c) Pyruvate from glycolysis
d) NADPH from photosystem II
e) ATP and NADPH from the light dependent reactions
_____39. The oxygen produced in the experiment was a direct result of
a) splitting of water in photosystem II
b) oxygen released in photosystem I
c) atmospheric oxygen used as an electron acceptor in the electron transport system
d) oxygen released by the aerobic bacteria
e) oxygen released when the carbon dioxide was used in the Calvin Benson Cycle
Questions 40-44:
a) Glycolysis
b) Chemiosmosis
c) Krebs cycle (citric acid cycle)
d) Light-dependent reactions of photosynthesis
e) Calvin cycle (light-independent reactions of photosynthesis)
_____40. Process in which 02 is released as a by-product of oxidation-reduction reactions
_____41. Process in which CO2 is released as a by-product of oxidation-reduction reactions
_____42. Process in which carbon from CO2 is incorporated into organic molecules
_____43. Process found in both photosynthesis and cellular respiration
_____44. Process in which sugar is oxidized to pyruvic acid
____45. Which of the following pathways for the transformation of cellular energy most likely evolved first?
a) Glycolysis b) C4 photosynthesis (c) Calvin cycle d) Citric acid (Krebs) cycle e) Cyclic photophosphorylation
_____46. Complete oxidative breakdown of glucose results in ____ ATP molecules.
a) 2 b) 4 c) 32 d) 36 e) 39
_____47. The first reaction in the Krebs cycle is binding
a) carbon dioxide to a four carbon molecule
b) carbon dioxide to a five carbon molecule
c) acetyl-CoA to a four carbon molecule
d) acetyl-CoA to a five carbon molecule
_____48. The first process in breaking down glucose is
a) glycolysis
b) the electron transport system
c) the Krebs cycle
d) fermentation
e) the transition reaction
_____49. Which process produces both NADH and FADH2?
a) glycolysis
b) the electron transport system
c) the Krebs cycle
d) fermentation
e) the transition reaction
_____50. The generation of hydrogen ion concentration gradients across membranes of the mitochondria is known as which theory of ATP production?
a) glycolytic b) phosphate pump c) chemiosmotic d) negative ion generator e) none of these
_____51. The greatest number of ATP molecules is produced in
a) alcoholic fermentation b) glycolysis c) the Kreb’s cycle d) lactic acid fermentation e) aerobic electron transport
_____52. If fermentation follows glycolysis,
a) NO2 will be one of the products as pyruvate is converted to lactate.
b) The two NADH molecules produced during glycolysis will (depending on the organism) be used to reduce
pyruvate to either lactate (lactic acid) or ethanol and CO2
c) ATP will be required to convert pyruvate to either lactic acid or ethanol and CO2
d) Oxidative phosphorylation occurs either on the plasma membrane or on derivatives of the plasma
membrane
_____53. The enzymes of the electron transport chain are bound to the surface of the cristae. The cristae
are folded inward in order to
a) decrease the intermembrane space
b) increase diffusion surface for glycolysis
c) separate the products from the substrate in the Krebs cycle
d) form a battery like "cells" for the electron transport chain
e) reduce the distance the FADH2 and NADH has to travel, and place the products of one reaction
near the enzymes for the next reaction
_____54. One turn of the Krebs cycle produces
a) 2 NADH, 2 FADH2, 2 ATP
b) 3 NADH, 1 FADH2, 1 ATP
c) 1 NADH, 3 FADH2, 2 ATP
d) 3 NADH, 2 FADH2, 1 ATP