1.9 Practice Problems

Transcription

1 1.9 Practice Problems 1. Solution: B It s not only chlorophyll a but a combination of pigments. 2. Solution: D See at what wavelength rate of photosynthesis is the highest. 3. Solution: D It s a fact. Know it!!! 4. Solution: D Remember, chlorophyll absorbs red and blue light while transmitting and reflecting green light. 5. Solution: D The pigment actually reflects photons of long wavelength light, if you look at the visible spectrum figure in this chapter, this should be clear. All the other answers are false. 6. Solution: B This follows from the text but you can also eliminate the other statements as being untrue. 7. Solution: D Statements 1, 2 and 4 are correct. Remember that chlorophyll reflects green light, it does not absorb it (statement 5) and not all forms of electromagnetic radiation can excite electrons in pigment molecules, only the visible light part of the spectrum (statement 3). 8. Solution: C The zygote is 2n and is the only diploid cell. Consult the diagram in this chapter. 9. Solution: D You should memorize this. Sexual reproduction in Chlamydomonas can only be achieved when a positive strain mates with a minus strain. 10. Solution: A Pigments are bound to protein in pigment-protein complexes. 11. Solution: D A, B and C are all ways that the ground state can be reestablished. D is not one of the ways. 12. Solution: A This is evident from the table. See mouse and humans. 1

2 2.3 Practice Problems 13. Solution: D Know it!!! 14. Solution: D Bacteria (prokaryote) 15. Solution: B Know it!!! 16. Solution: C Methane-producing bacteria (prokaryote) 17. Solution: A Know it!!! 18. Solution: D Know it!!! 19. Solution: D Know it!!! 20. Solution: B This is important information. Single-stranded RNA is common. 2

3 3.6 Practice Problems 21. Solution: A Alpha helix and beta sheets are examples of secondary structure of proteins. 22. Solution: B Can t be easier than this!!! 23. Solution: C Hydrolysis is breaking down complexes by the addition of water. It is the opposite of condensation/dehydration reaction. 24. Solution: D They can be both hydrophobic and hydrophobic. 25. Solution: C Primary structure alteration means a change in the amino acid sequence. 26. Solution: D Alpha helix is an example of a secondary structure. 27. Solution: D 1, 2 and 3 are correct. 28. Solution: A It is the side chain which determines this. 29. Solution: C It is a condensation/dehydration reaction. 30. Solution: 3 It is always an N-C bond. 5 end of mrna corresponds to the N- terminal and 3 end to C-terminal. 31. Solution: C The most likely scenario is that a nonsense mutation took place, leading to a stop codon and a truncated protein. 32. Solution: E A Northern blot is going to tell you if the mrna is present; however it cannot tell you if there is functional protein. 33. Solution: C Both the tertiary structure and the function of the protein may change if you change a protein s primary structure. 34. Solution: B The breakdown of proteins in the body often releases nitrogen. 35. Solution: C Denatured proteins have a higher energy state than the native conformation. Denatured proteins can regain their native conformation and still have primary structure. Answer D is irrelevant. 36. Solution: C You can make a lot of mrna but if it is being degraded then you will not have the same corresponding amount of protein. 3

4 4.4 Practice Problems 37. Solution: D It is correct that substances that are stable have low free energy (are not in an excited state). Living things are certainly not always at equilibrium (answer C), closed systems can certainly reach equilibrium (answer A) and B is irrelevant. 38. Solution: A Yes, memorize this! Enzymes always lower the activation energy of a reaction. The other three answers are untrue. 39. Solution: D If energy is released, the reaction is exergonic, i.e., free energy is negative which also means the reaction is spontaneous. 40. Solution: D All of the above are true and good items to memorize for your test. 41. Solution: D An enzyme will not change the free energy but it will lower the activation energy. 42. Solution: B This is more memorization than anything. 43. Solution: A Temperature and/or ph can change the 3-D shape of an enzyme. 44. Solution: C Decreasing the concentration of substrate will not change the rate of an enzyme-catalyzed reaction. 45. Solution: C Increasing the temperature may cause the proteins to change and we may not want that. 46. Solution: C Energy can always be converted, it cannot be destroyed or produced according to the first law. 47. Solution: D Again, memorize this! 48. Solution: D All of the above are true. 49. Solution: D You should think of ATP as a source of energy for all cells. 50. Solution: B B is correct, this is the opposite of an exergonic reaction. 51. Solution: C Proteins denature at high temperatures and this is not good for a cell! 4

5 5.8 Practice Problems Solution: A CFTR pumps chloride into the lining making statement 1 untrue, not all molecules move by simple diffusion making statement 2 untrue and statement 4 is just a distraction that is entirely untrue. Statements 3 and 5 are correct. 53. Solution: E Small, hydrophobic molecules can easily pass through the membrane (B and C). 54. Solution: A This is the definition of passive diffusion. Passive diffusion does not involve transport proteins. 55. Solution: B To be amphipathic is to have two different affinities, which is true for biological membranes. 56. Solution: B The rate of movement does depend on the hydrophobicity of the molecule and the concentration gradient. The other statements (2, 3 and 4) are incorrect. 57. Solution: C Transportation of water and transportation of molecules to areas of lower concentration happen without the need for energy. However, moving molecules to an area of higher concentration requires energy (ATP) to be utilized. 58. Solution: C The only option which is true always is C; transporters change conformation when transporting molecules. 59. Solution: D This is a relatively easy question but good review; all of these factors increase the fluidity of the bilayer. 60. Solution: E These are good properties to memorize! 61. Solution: D Membrane proteins do not themselves store amino acids. The other answers are all true. 62. Solution: A Higher temperatures increase fluidity, making B incorrect. Lower protein content and lower amounts of large glycolipids both increase fluidity, making C and D incorrect. The greater the proportion of unsaturated phospholipids, the more fluid the membrane, making A correct. 5

6 6.6 Practice Problems 63. Solution: d) This should be fairly clear from this chapter, light energy is the driving force at work in the removal of electrons form chlorophyll molecules. 64. Solution: a) Photosystem II undergoes photolysis, not photosystem I. Also, harvesting of light energy by chlorophyll occurs in PSII and not in PSI. 65. Solution: d) If the thylakoid is punctured, it will most likely affect ATP synthesis primarily since the photosystems are in the thylakoid. 66. Solution: e) Mostly a memorization question. You should know that a photosystem means both an antenna and a reaction center. 67. Solution: d) This occurs in the thylakoids (PSI and PSII) and produces these three products. 68. Solution: b) In order for photosynthesis to take place, energy must be available, an electron donor must also be available and there must be carbon to act on. 69. Solution: d) Chlorophyll is the target. 70. Solution: a) The stroma where the Dark reaction (Calvin cycle takes place). 71. Solution: b) This should be a pretty simple question. The photosystems are in the Thylakoids. 6

7 7.2 Practice Problems 72. Solution: B B is correct. The other statements are all false. Glucose is more stable than glucose-6-phosphate, ATP is the energy required not the enzyme, the Pi group does not get transferred to Glucose. 73. Solution: C This is fairly straight memorization however a good reminder to review your diagrams and understand each step. 74. Solution: E This is the most correct answer and the important end products of glycolysis. 75. Solution: c) We want the reactions to move forward through the stages of cellular respiration, this is better achieved when chemical reactivity is high. 7

8 8.7 Practice Problems 76. Solution: A Overall, the pathway released energy, therefore the pathways was catabolic. Conversion of A into B is actually exothermic (released energy), we have no reason to believe that intermediate B is necessarily encoded by a gene and energy is not required, but released in the conversion of C to D. 77. Solution: B This is a good example of a question that looks difficult but can be reasoned out quite quickly. They simply want to know where the most ATP is generated, the answer is Krebs (Citric Acid Cycle) and Oxidative Phosphorylation. 78. Solution: A This is fairly straight memorization. You should know that Acetyl CoA is a part of the Citric Acid Cycle. 79. Solution: C Instead of finding an alternative, the cells would not know what to do and would simply build up acetyl-coa and not know how to move forward without oxygen. Fermentation would happen if HIF was active; inhibition of pyruvate should not be a consequence and the cells will not even get to the point of oxidative phosphorylation and so this will definitely decrease in rate. 80. Solution: B We love and need our ATP! We require a lot more energy than a yeast cell. 81. Solution: B Cytochrome c is the donor. 82. Solution: B This isn t ideal, but it keeps things going. NAD + gets regenerated and the cycle can continue. 8