Biology Ch. 3 Sec 4 Notes
Key Ideas
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Where do living things get energy?
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How do chemical reactions occur?
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Why are enzymes important to living things?
Changing Matter
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Living things are made of ______________, which consists of a substance with a form.
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_____________________ constantly occur in living things.
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A ___________________ ________________ occurs when only the form or shape of the matter
changes.
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A ______________ ______________ occurs when a substance changes into a different
substance.
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Matter is neither ____________ nor _____________________ in any change.
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This observation is called the _______________________________________________.
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The ability to move or change matter is called ___________________.
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Energy exists in many forms and can be ______________ from ________ form to another.
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Every ___________ in matter requires a change in _____________.
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_______________ may change from one form to another, but the total amount of ___________
does not change.
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This observation is called the law of __________________________________________.
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The total amount of usable energy __________________ because some energy is given off to
the surroundings as ____________.
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Living things use different _________________ ________________________ to get the energy
needed for life processes.
Chemical Reactions
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Changing a substance requires a _______________ reaction.
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During this process, _________ between atoms are broken, and new ones are formed.
A _______________________ is a substance that is changed in a _________________ reaction
Biology Ch. 3 Sec 4 Notes
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A ______________________ is a new substance that is formed.
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Sometimes products can reform reactants.
Activation Energy
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__________________ reaction can only occur under the right conditions.
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To form __________ bonds, the particles must collide ___________ enough to overcome the
repulsion between their ________________ charged electron clouds.
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The ________________ _________________ of a reaction is the minimum kinetic energy
required to start a chemical reaction.
Alignment
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Even if enough energy is available, the _______________ still may not form.
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With the ________________ particles, the _______________ atoms must be brought close
together in the proper orientation.
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______________ ________________ can only occur when the activation energy is available and
the correct atoms are aligned.
Biological Reactions
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In living things, chemical reactions occur between ___________, complex _________________.
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Many of these reactions require large ____________________ ______________________.
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Many of these reactions would not occur quickly enough to sustain life without the help of
_______________________.
Enzymes
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An _____________________ is a molecule that increases the speed of biochemical reactions.
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Enzymes hold molecules ______________ together and in the _____________ orientation.
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An enzyme _____________ the activation energy of a reaction.
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By assisting in necessary biochemical reactions, enzymes help organisms maintain homeostasis.
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Each enzyme has an ________ __________, the region where the reaction takes place.
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The shape of the active site determines which _______________, or ________________, will
bind to it.
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Each __________________ enzyme acts only on specific substrates.
Biology Ch. 3 Sec 4 Notes
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__________ of the substrates causes the enzyme’s _____________ to change.
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This change causes some bonds in the substrates to ________ and new bonds to ______
Many enzymes are _______________.
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Changes in _______________________ and _________ can change a protein’s shape.
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If an enzyme changes __________, it won’t ____________ well.
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Most enzymes need a certain ____________ of ______________ and _____.
Metabolism
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Cells get most of the __________ needed for _______________________ by breaking down
food molecules.
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The ____________ of energy from food molecules occurs in a series of reactions using many
______________________ to capture energy in the form of ______ molecules.
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The ____________ reduce the activation energy so much that only a ______________ energy is
needed to start the reactions.
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In this process, very little _____________ is lost as _______.
Summary
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Living things use different chemical reactions to get the energy needed for life processes.
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An activation energy is needed to start a chemical reaction. The reactants must also be aligned
to form the product.
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By assisting in necessary biochemical reactions, enzymes help organisms maintain homeostasis.