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25 Cards in this Set

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The laws of thermodynamics define the properties and behavior of energy. The first law states that energy __________.
cannot be created or destroyed but can be changed from one form into another
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 __________.
the second law of thermodynamics
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 __________.
decreases, increases
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.
reactants, products
In endergonic reactions, __________.
Endergonic reactions require an input of energy
The speed of a reaction is determined by its
activation energy-The activation energy (the energy input required to start a reaction) determines the reaction rate.
Enzymes are a class of proteins that catalyze chemical reactions in cells. Like all other catalysts, they speed up chemical reactions by __________.
lowering the activation energy of the reaction
The most important reason a particular enzyme can function only within certain limits of temperature, salt conditions, and pH is that __________
changes in temperature, salt, and pH change the shape of an enzyme
ATP is well suited to its role as an energy-carrier molecule in cells because __________.
the covalent bond between the last two phosphates can be broken to release substantial amounts of energy
A substance that is acted upon by an enzyme to produce a product is called a(n) __________.
substrate
ATP is well suited to its role as an energy-carrier molecule in cells because __________.
the covalent bond between the last two phosphates can be broken to release substantial amounts of energy
If all matter tends toward increasing randomness and disorder, how can life exist?
There is a constant input of energy from the sun.
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 __________.
feedback inhibition
The laws of thermodynamics __________.
define the basic properties and behavior of energy
Biological catalysts __________.
are organic substances that lower the activation energy required to initiate a reaction that would normally take place at a slower rate
Lysosomes have an acidic interior (pH = 5), unlike the rest of the cell (pH = 7). Lysosomal enzymes are most active at __________.
pH = 5
The energy of movement is called
kinetic energy
Without energy, processes that proceed spontaneously result in an increase in ____________________.
entropy
A ____________________ is a process that breaks and forms chemical bonds.
chemical reaction
____________________ is the most common energy-carrier molecule in cells
ATP
The ____________________ of a cell is the sum of all of its chemical reactions
metabolism
____________________ are biological catalysts synthesized by living organisms.
Enzymes
How does an enzyme increase the speed of a reaction?
by lowering activation energy requirements
ATP is important in cells because
it transfers energy from exergonic reactions to endergonic reactions
What is predicted by the second law of thermodynamics?
Systems always tend toward greater states of disorder.