ESSENTIAL CELL BIOLOGY FOURTH EDITION CHAPTER 3 ENERGY CATALYSIS AND BIOSYNTHESIS 2014 GARLAND SCIENCE PUBLISHING The Use of Energy by Cells 3 1 Chemical reactions carried out by living systems depend on the ability of some organisms to capture and use atoms from nonliving sources in the environment The specific subset of these reactions that break down nutrients in food can be described as a metabolic b catabolic c anabolic d biosynthetic 3 2 When there is an excess of nutrients available in the human body insulin is released to stimulate the synthesis of glycogen from glucose This is a specific example of a n process a general process in which larger molecules are made from smaller molecules a metabolic b catabolic c anabolic d biosynthetic 3 3 The second law of thermodynamics states that the disorder in any system is always increasing In simple terms you can think about dropping NaCl crystals into a glass of water The solvation and diffusion of ions is favored because there is an increase in a pH b entropy c ions d stored energy 3 4 The energy used by the cell to generate specific biological molecules and highly ordered structures is stored in the form of a Brownian motion b heat c light waves d chemical bonds 3 5 At first glance it may seem that living systems are able to defy the second law of thermodynamics However on closer examination it becomes clear that although cells create organization from raw materials in the environment they also contribute to disorder in the environment by releasing a water b radiation Page 1 of 30 c d heat proteins 3 6 If you weigh yourself on a scale one morning then eat four pounds of food during the day will you weigh four pounds more the next morning Why or why not Hint What happens to the atoms from the food you ingested 3 7 In the cytoplasm materials are organized separated and sorted by membranes Cells exploit the selective permeability of these membranes to partition populations of molecules and generate chemical energy for the cell Use the principles of the first and second laws of thermodynamics to explain how membranes can be used to produce chemical energy 3 8 Indicate whether the following statements are true or false If a statement is false explain why it is false A The second law of thermodynamics states that the total amount of energy in the Universe does not change B The ultimate source of energy for living systems is chlorophyll C CO 2 gas is fixed in a series of reactions that are light dependent D H 2 is the most stable and abundant form of hydrogen in the environment 3 9 Two college roommates do not agree on the best way to handle the clutter piled up in your dorm room Roommate 1 explains that chaos is inevitable so why fight it Roommate 2 counters that maintaining an organized environment makes life easier in many ways and that chaos is not inevitable What law of thermodynamics drives the thinking of Roommate 1 What thermodynamic argument can be used to support Roommate 2 3 10 Assume that the average human adult requires 2000 kilocalories per day to sustain all normal processes and maintain a constant weight If manufactured solar panels could somehow provide power directly to the human body what size solar panel would be required in cm2 Assume there are 10 hours of sunlight per day and that the usable energy output for a typical solar panel is 850 kJ ft2 per hour Note 1 kcal 4 184 kJ 1 ft2 929 03 cm2 3 11 In the first stage of photosynthesis light energy is converted into what other form of energy a electrical b chemical c potential d kinetic 3 12 Fill in the blanks selecting from the choices below Light heat sugars Page 2 of 30 CO CO 2 O 2 H2 H 2 O N 2 NO 3 13 During respiration energy is retrieved from the high energy bonds found in certain organic molecules Which of the following in addition to energy are the ultimate products of respiration a CO 2 H 2 O b CH 3 H 2 O c CH 2 OH O 2 d CO 2 O 2 3 14 Your body extracts energy from the food you ingest by catalyzing reactions that essentially burn the food molecules in a stepwise fashion What is another way to describe this process a reduction b oxidation c dehydration d solvation 3 15 Oxidation is a favorable process in an aerobic environment which is the reason cells are able to derive energy from the oxidation of macromolecules Once carbon has been oxidized to its most stable form it can only cycle back into the organic portion of the carbon cycle through a CO 2 photosynthesis b CH 3 combustion c CO 2 respiration d CO reduction 3 16 For each of the pairs A D in Figure Q3 16 pick the more reduced member of the pair Page 3 of 30 Figure Q3 16 3 17 Oxidation is the process by which oxygen atoms are added to a target molecule Generally the atom that is oxidized will experience which of the following with respect to the electrons in its outer shell a a net gain b a net loss c no change d an equal sharing 3 18 When elemental sodium is added to water the sodium atoms ionize spontaneously Uncharged Na becomes Na This means that the Na atoms have been a protonated b oxidized c hydrogenated d reduced 3 19 Indicate whether the following statements are true or false If a statement is false explain why it is false A Photosynthetic organisms release only O 2 into the atmosphere while nonphotosynthetic organisms release only CO 2 B The cycling of carbon through the biosphere first requires the incorporation of inorganic CO 2 into organic molecules C The oxidation of one molecule is always coupled to the reduction of a second molecule D During cellular respiration carbon containing molecules become successively more oxidized until they reach their most oxidized form as CO 2 Page 4 of 30 3 20 Arrange the following molecules in order with respect to their relative levels of oxidation assign 5 to the most oxidized and 1 to the most reduced CH 2 O formaldehyde CH 4 methane CHOOH formic acid CH 3 OH methanol CO 2 carbon dioxide 3 21 Oxidation and reduction states are relatively easy to determine for metal ions because there is a measurable net charge In the case of carbon compounds oxidation and reduction depend on the nature of polar covalent bonds Which of the following is the best way to describe these types of bond a hydrogen bonds in a nonpolar solution b covalent bonds in an aqueous solution c unequal sharing of electrons across a covalent bond d equal sharing of electrons across a covalent bond 3 22 Seed oils are often dehydrogenated and added back into processed foods as partly