Part I: Short answer (25 points)

Transcription

1 Part I: Short answer (25 points) Part I: / 25 Part II: / AURI-SLIM is a pair of Dieter s Earrings. The ad says, Why starve yourself when an attractive piece of fashion jewelry can do the weight loss work for you? TOTAL: / 100 It also says that ETHM ZURICH Research Center conducted clinical trials. If you worked for ETHM, how would you design an experiment to test the claim that wearing these earrings will boost weight loss? Describe your overall approach, and identify your independent variable, control, dependent variable, and two or more standardized variables (6 points). 2. a. (1 point) The covalent bonds in water are [circle one] polar nonpolar b. Explain your answer to part a, using the hogginess chart on the next page. (2 points) c. In the space at right, draw two water molecules joined by a hydrogen bond. Label at least one covalent bond, the hydrogen bond, and the regions of partial positive and partial negative charges (4 points). 3. An insect called a cicada periodically sheds its shell as it develops into an adult. Some cicadas, however, produce defective shells that trap the insects inside. They therefore starve to death before they are old enough to reproduce. How would natural selection keep this abnormal trait rare? (3 points) 4. a. Where does a potato plant get the C atoms in its starch molecules? (1 point) b. Trace the steps required for a C atom to get from the starch into one of your muscle cells (4 points). c. Trace the path of energy from sunlight to the bonds in ATP in one of your muscle cells (4 points). 1

2 Part II: 75 points (38 questions; each question is worth 2 points, except the last) True-false (mark A for true, B for false): 1. Starch and cellulose are similar because they are both polysaccharides made by plants, but they are different because animals can digest starch but not cellulose. 2. CO 2 and H 2 O are considered organic molecules because plants require them for survival. 3. Photosynthesis is important because it directly produces all of a plant cell s ATP. 4. A neon atom has two vacancies in its outermost shell and therefore likes to make two bonds. [Hint: Draw the atom; its atomic number is 10.] Multiple choice / matching: 5. Evolution is the best scientific explanation for: a. the improving function of the iphone over the years. b. today s diversity of life. c. the cellulose cell walls in animal cells. d. the origin of life on Earth. e. the observation that all species that have ever lived are still here today. 6. How many of the following seven statements are FALSE? o A 13 C isotope has the same number of electrons as a 14 C isotope. o An atom s nucleus contains electrons. o Hydrogen bonds are polar covalent bonds. o A neutron s charge is opposite that of a proton. o Two negatively charged ions can form an ionic bond with each other. o Ionic bonds form between atoms with partial charges. o A water molecule forms when an O atom forms hydrogen bonds with two H atoms. a. two b. three c. four d. five e. six 7. What would happen to animal life if the sun went dark tomorrow and never gave off light again? a. All of the carbon atoms would disappear because atoms require light energy to exist. b. All of the energy in chemical bonds would disappear because covalent bonds require light energy. c. Eventually the plants would die without light, and the animals would die of starvation and/or lack of O 2. d. A lot of animals would die at first, but eventually they would evolve a way to survive, and their populations would recover to today s numbers. e. All of the plants would die, but animals don t rely on photosynthesis so they would be all right. 8. A recent visitor to our department talked about how he measured temperature, soil moisture, and the effects fire on the plants and fungi in a pine forest. He conducts his research at the level of the organizational hierarchy. a. ecosystem b. population c. organism d. cell 2

3 9. Suppose you want to know if lotion, spray, or stick sunscreen works best. You plan to recruit 20 volunteers. On each one, you plan to divide a patch of skin into four areas: one with no sunscreen and one each for the lotion, spray, and stick. What s something else you should definitely NOT do? a. Make sure each sunscreen has the same SPF rating (e.g., SPF 50). b. Find a way to measure which sunscreen works best. c. Make sure all the volunteers have similar skin tones (pigmentation). d. Expose each patch of skin to a different amount of UV radiation. e. Find a way to make sure you use the same amount of each sunscreen on each patch. 10. You find it hard to find enough volunteers for the experiment SPF"75"0"2" described in the previous question, so SPF"75"0"1" you try a different approach. Your hypothesis is that the higher a SPF"25"0"2" sunscreen s SPF, the better the protection. You recruit six SPF"25"0"1" volunteers; two get SPF 25 sunscreen, two get SPF 75 sunscreen, None"0"2" and two get no sunscreen. You expose them all to sunlight and None"0"1" measure the skin redness 3 hours later. The results are graphed at right. Redness&(scale&of&1.10)& Should you support or reject your hypothesis, and why? a. Support; all four subjects with sunscreen had at least twice the sun protection compared to those without sunscreen. b. Reject; two subjects per treatment is not enough to draw any conclusions, especially since people vary so much in their response to sun exposure. c. Support; SPF 75 s results were always better than SPF 25 s results. d. Reject; sunscreen effectiveness can t be measured on skin. 11. How many independent variables are in the experiment in the previous question? a. zero b. one c. two d. three e. six 12. Are the data in the graph at right continuous or discrete, and does the graph show the correct way to graph them? a. They are continuous, so the line graph shown is the correct choice. b. They are discrete, so the line graph shown is the correct choice. c. They are continuous, so a bar graph would have been a better choice. d. They are discrete, so a bar graph would have been a better choice. 13. Like all other objects in the universe, a glucose molecule contains: a. atoms only. c. neither a nor b. b. energy only. d. both a and b. Subject& 0" 1" 2" 3" 4" 5" 6" 7" 8" 9" 10" 3

4 The following can be compared in a quantitative sense. Use the choices below to describe the paired statements. a. The first is greater than the second b. The second is greater than the first c. The two are essentially equal 14. Number of CO 2 molecules produced in the respiration of 10 glucose (C 6 H 12 O 6 ) molecules number of O 2 molecules produced in the respiration of 10 glucose molecules 15. Number of domains represented in this list: plants, fungi, bacteria, protists number of eukaryotic kingdoms represented in the same list 16. Number of mitochondria in an average archaea cell number of mitochondria in an average plant cell Suppose you eat some protein-rich nuts. If your digestive system broke down the nut proteins into their monomers and your cells absorbed them, could the monomers join to each other to form DNA in your cells? a. Yes, because DNA is a type of protein. b. Yes, because any monomer can substitute for any other type of monomer in living cells. c. No, because plant monomers are not useful to animal cells. d. No, because DNA is made of a different type of monomer from protein. e. It depends on the species of nuts. 18. What type of molecule is shown at right? a. Polysaccharide b. DNA c. RNA d. Protein e. Fat 19. I found a website that encourages students to look at cells from the following organisms, some of which you saw in the microscopy lab: Daphnia (a small animal); mashed banana; Elodea (an aquatic plant); human cheek cells; protists in pond water; yeast (a type of fungus); and bacteria from yogurt. Which of the following cell features is correctly matched with a list of organisms with that feature? a. Cell wall Daphnia, banana, Elodea, human cheek cells b. Ribosomes all of the cells, except the bacteria c. Cell membrane all of the cells d. Chloroplasts Elodea, protists in pond water, yeasts e. Nucleus all of the cells 4

5 20. The first question on this exam mentioned AURI-SLIM Dieter s Earrings. According to the ad, a metabolism-boosting energy current runs from the earlobe to the stomach, making it easy to shed 30, 40, even 50 pounds. I hope you already know that wearing earrings will not boost your internal metabolic rate. What would be a more effective and healthy way to lose weight over the course of a month? a. Eat all the calories you want, but eliminate an entire category of organic molecules (e.g., protein) from your diet. b. Eat all the calories you want, but quit drinking water, since your body consists mostly of water. c. Tip the calorie balance so that you spend more in exercise and other activities than you take in with your food. d. Switch to an all-celery diet, since celery requires more energy to digest than it delivers. e. Switch to an all-meat diet, since that s what our ancestors used to eat. 21. Chloroplasts: a. are the organelles in plant cells that turn food energy into ATP. b. use sunlight to convert CO 2 and H 2 O into glucose. c. are structures inside animal cells that break down sugars so our bodies can digest them. d. help break up sugars so humans can digest them. e. are layers around cells that help break down food into ATP, which can then enter the cell. 22. In the image at right, W is a: a. cell. d. sugar molecule. b. phospholipid. e. nucleus. c. protein. 23. In the image at right, Z can pass freely through layer Y. Based only on this observation, Z is most likely to be: a. an O 2 molecule. d. a polar amino acid. b. a Cl - ion. e. an H + ion. c. a glucose molecule. 24. In the image at right, layer Y is made up mostly of: a. DNA. d. H + ions. b. cytoplasm. e. monosaccharides. c. phospholipids. 25. You can t add fresh pineapple to Jell-o because it has enzymes that break down the gelatin protein; the Jell-o won t form a gel. It is fine to add canned pineapple though; canned fruit is heated before being sealed in a can. Why doesn t canned pineapple ruin the Jell-o? a. The heat destroys the bacteria that spoil the Jell-o. b. The heat denatures the enzymes that break down the gelatin. c. Sealing the pineapple in a can eliminates the oxygen required for the enzyme to function. d. Sealing the pineapple in a can destroys the organic molecules that make up the pineapple. 5

6 26. In the evolutionary tree at right, which node represents the most recent common ancestor shared by peccaries and whales? a. A b. B c. C d. D e. E 27. A protein consists of 190 amino acids. How many P atoms are in the protein? a. 0 d. 190 x 5 = 950 b. 190 e. 190 x 100 = 19,000 c. 190 x 3 = What is the relationship between ATP and O 2? a. In animals, O 2 participates in the ATP hydrolysis reaction. b. In plants, ATP hydrolysis releases O 2 as waste. c. Plant and animal cells use O 2 in respiration, which produces ATP. d. Plant cells use O 2 in photosynthesis, which produces ATP. e. All of the above are correct. D 29. My cat, Sidecar, loves eating Fancy Feast. Which of the following is/are possible fate(s) for the atoms in his cat food? a. They could be released from his body in the form of heat energy. b. They could be released from his body in the form of CO 2. c. They could be incorporated into the organic molecules that make up his cells. d. They could be released from his body as light energy. e. Two of the above are correct. 30. What do the digestive enzymes in Sidecar s small intestine do to his Fancy Feast meal? a. Speed up hydrolysis reactions b. Speed up respiration reactions c. Speed up dehydration synthesis reactions d. a, b, and c are all possible; it depends on what his body needs 31. In the starch digestion activity of last week s lab, iodine turned blue in the presence of starch. You added hydrochloric acid to one of your test tubes, predicting that the acid would denature the starchdigesting enzymes in the test tube. The control tube had the same volume of fluid but did not contain acid. A reasonable prediction would be that: a. the ph in the control tube would go down before the reaction even started. b. the ph in the acid-treated tube would go up before the reaction even started. c. the acid-treated tube would start blue but turn colorless by the end of the experiment. d. the control tube would start blue but turn colorless by the end of the experiment. A" B" E" C" 6

7 32. In the diagram at right, which molecule represents a polysaccharide? a. X b. Y c. Z X" 33. In the diagram at right, which molecule is most hydrophobic? a. X b. Y c. Z 34. Your friend knows that freezing preserves raw meat, so she concludes that she can extend her life by sleeping in a freezer. What do you say? a. Sure, that should work. You ll live one hour longer for every hour you spend in the freezer. b. Sure, that should work. Your cell s chemical reactions will slow down to a crawl, but chemical reactions aren t necessary for life anyway. c. Umm, I wouldn t do that. It ll be too dark for your cells to carry out photosynthesis, so you ll starve after one night. d. Umm, I wouldn t do that. As soon as ice crystals form in your cells, they will cause your cell membranes to rupture and you will die. Y" 35. I recently went to a seminar about fruit flies. The speaker mentioned something about long-chain fatty acids on the fly s exterior. When he said that, he was talking about a. proteins d. ATP b. carbohydrates e. lipids c. DNA 36. That speaker also mentioned fly proteins. Which molecule shown at right might be part of a protein? (Bubble in the corresponding letter.) 37. Which structure shown at right is most like the structure of ATP? (Bubble in the corresponding letter.) 38. Which test form do you have? (1 point) a. Form 1 (green) b. Form 2 (pink) 7 Z"