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25 Cards in this Set
- Front
- Back
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The laws of thermodynamics define the properties and behavior of energy. The first law states that energy __________.
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cannot be created or destroyed but can be changed from one form into another
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When electrical energy is used to turn on a lightbulb, the conversion from electrical energy to light energy is not 100% efficient. This loss of usable energy can be explained by __________.
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the second law of thermodynamics
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The second law of thermodynamics relates the organization of matter to energy. It states that unless additional energy is acquired, the orderliness of a system tends to __________, whereas entropy __________.
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decreases, increases
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In a chemical reaction, the __________ are the atoms or molecules that enter into the reaction, and the __________ are the chemicals or atoms produced by the reaction.
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reactants, products
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In endergonic reactions, __________.
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Endergonic reactions require an input of energy
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The speed of a reaction is determined by its
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activation energy-The activation energy (the energy input required to start a reaction) determines the reaction rate.
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Enzymes are a class of proteins that catalyze chemical reactions in cells. Like all other catalysts, they speed up chemical reactions by __________.
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lowering the activation energy of the reaction
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The most important reason a particular enzyme can function only within certain limits of temperature, salt conditions, and pH is that __________
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changes in temperature, salt, and pH change the shape of an enzyme
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ATP is well suited to its role as an energy-carrier molecule in cells because __________.
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the covalent bond between the last two phosphates can be broken to release substantial amounts of energy
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A substance that is acted upon by an enzyme to produce a product is called a(n) __________.
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substrate
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ATP is well suited to its role as an energy-carrier molecule in cells because __________.
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the covalent bond between the last two phosphates can be broken to release substantial amounts of energy
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If all matter tends toward increasing randomness and disorder, how can life exist?
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There is a constant input of energy from the sun.
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The amino acid threonine is converted to isoleucine by a sequence of five enzymatic reactions. When isoleucine levels are high, the first reaction in this sequence is “turned off.” This is an example of __________.
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feedback inhibition
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The laws of thermodynamics __________.
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define the basic properties and behavior of energy
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Biological catalysts __________.
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are organic substances that lower the activation energy required to initiate a reaction that would normally take place at a slower rate
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Lysosomes have an acidic interior (pH = 5), unlike the rest of the cell (pH = 7). Lysosomal enzymes are most active at __________.
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pH = 5
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The energy of movement is called
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kinetic energy
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Without energy, processes that proceed spontaneously result in an increase in ____________________.
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entropy
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A ____________________ is a process that breaks and forms chemical bonds.
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chemical reaction
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____________________ is the most common energy-carrier molecule in cells
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ATP
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The ____________________ of a cell is the sum of all of its chemical reactions
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metabolism
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____________________ are biological catalysts synthesized by living organisms.
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Enzymes
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How does an enzyme increase the speed of a reaction?
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by lowering activation energy requirements
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ATP is important in cells because
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it transfers energy from exergonic reactions to endergonic reactions
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What is predicted by the second law of thermodynamics?
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Systems always tend toward greater states of disorder.
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