Thur, Nov 21st : 2.4-2.5 notes/ 2.4-2.5 SG (attached)
Biology – Sec. 2.4 & 2.5 Outline
Name: ______________________ Date: ________________ Pd: ___
Sec. 2.4 KEY CONCEPT
Life depends on chemical reactions.
 Bonds break and form during chemical reactions.
•
Chemical reactions ____________ substances into
different ones by _____________ and ____________
chemical bonds.
–
•
•
–
____________ are changed during a chemical
reaction.
___________ are made by a chemical reaction.
Bond energy is the amount of _________ that
________ a bond.
–
–
Energy is added to __________ bonds.
Energy is released when bonds ________.
A reaction is at ______________ when reactants and
products form at the _________ rate.
 Chemical reactions release or absorb energy.
•
•
Activation energy is the amount of __________ that
needs to be absorbed to _________ a chemical
reaction.
Exothermic reactions _________ more energy than
they absorb.
–
Reactants have ___________ bond energies than
products.
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
1
Chemistry of Life
Section 4: Chemical Reactions
•
–
Excess energy is ___________ by the reaction.
Endothermic reactions absorb _________ energy
than they ______________.
–
–
Reactants have lower ______ energies than
products.
Energy is ____________ by the reaction to make
up the difference.
Sec. 2.5 KEY CONCEPT
Enzymes are catalysts for chemical reactions in living things.
 A catalyst _________ activation energy.
•
Catalysts are substances that ________ ___
chemical reactions.
–
–
___________ activation energy
__________ reaction rate
 Enzymes allow chemical reactions to occur under
tightly controlled conditions.
•
•
Enzymes are ___________ in living things.
–
–
Enzymes are __________ for almost all
____________.
Most enzymes are __________.
Disruptions in homeostasis can ___________
enzymes from ________________.
–
–
–
Enzymes function best in a _______ range of
conditions.
Changes in ____________ and ____ can break
hydrogen bonds.
An enzyme’s function depends on its
_____________.
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
2
Chemistry of Life
Section 4: Chemical Reactions
•
•
An enzyme’s structure allows only ___________
reactants to ________ to the enzyme.
–
–
_______________
__________ site
The ___________________ model helps illustrate
how enzymes function.
–
–
substrates ___________ together
bonds in substrates _____________
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
3
Chemistry of Life
Section 4: Chemical Reactions
Section 2.4: Chemical Reactions
Study Guide
KEY CONCEPT
Life depends on chemical reactions.
VOCABULARY
chemical reaction
bond energy
exothermic
reactant
equilibrium
endothermic
product
activation energy
MAIN IDEA: Bonds break and form during chemical reactions.
1. Label the reactants and products in the chemical reactions shown below.
______________________________
CH4 + 2O2
CO2 + 2H2O
________________________________
______________________________
6CO2 + 6H2O
6O2 + C6H12O6
________________________________
Circle the word or phrase that best completes the sentence.
2. During a chemical reaction, chemical bonds / solutes break and reform.
3. Reactants / products are the substances changed during a chemical reaction.
4. Bond energy is the amount of energy it takes to break a bond between two
atoms / ions.
5. Equilibrium occurs when reactants and products are made at the same rate /
different rates.
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
4
Chemistry of Life
Section 4: Chemical Reactions
Study Guide A continued
MAIN IDEA: Chemical reactions release or absorb energy.
Choose whether the statement is true or false.
6. true / false Not all chemical reactions involve changes in energy.
7. true / false Activation energy is required for a chemical reaction to start.
8. true / false Some chemical reactions release more energy than they absorb,
while others absorb more energy than they release.
9. true / false Chemical reactions can occur whether or not energy is added to the
reactants.
10. true / false An exothermic chemical reaction absorbs more energy than it
releases.
Vocabulary Check
Draw lines to connect the words or phrases that mean the same thing.
11. endothermic reaction
substances changed during a
chemical reaction
12. exothermic reaction
substances made by a chemical reaction
13. activation energy
chemical reaction that releases more
energy than it absorbs
14. reactants
chemical reaction that absorbs more
energy than it releases
15. products
amount of energy that needs to be
absorbed for a chemical reaction to start
16. equilibrium
amount of energy that will break a bond
between two atoms
17. bond energy
state reached when reactants and
products are made at the same rate
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
5
Chemistry of Life
Section 4: Chemical Reactions
Section 2.5: Enzymes
Study Guide
KEY CONCEPT
Enzymes are catalysts for chemical reactions in living things.
VOCABULARY
catalyst
substrate
enzyme
MAIN IDEA: A catalyst lowers activation energy.
Choose the best answer to the question.
1. Activation energy is the energy required to
a. complete a chemical reaction.
b. start a chemical reaction.
c. produce a catalyst.
d. produce the reactants.
2. Which of the following can reduce the amount of energy needed for a
chemical reaction to take place?
a. reactant
b. product
c. catalyst
d. hydrogen bond
3. What happens to the speed of a chemical reaction when a catalyst is present?
a. It speeds up.
b. It slows down.
c. It stays the same.
d. It becomes erratic.
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
6
Chemistry of Life
Section 3: Carbon-Based Molecules
Study Guide A continued
MAIN IDEA: Enzymes allow chemical reactions to occur under tightly controlled
conditions.
4. Take notes about enzymes by filling in the Main Idea Web below.
What physical factors affect the
action of enzymes?
Where do enzymes act as catalysts?
Enzymes
How do enzymes affect the
speed of chemical reactions in
the body?
How does a substrate affect an
enzyme?
Vocabulary Check
Circle the word or phrase that best completes the sentence.
5. A catalyst can increase / decrease the amount of energy needed to start a
chemical reaction.
6. Substrates are to catalysts / enzymes as keys are to locks.
7. Enzymes / substrates are catalysts for chemical reactions in living things.
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
7
Chemistry of Life
Section 3: Carbon-Based Molecules
Section 2.3: Carbon-Based Molecules
Study Guide
KEY CONCEPT
Carbon-based molecules are the foundation of life.
VOCABULARY
monomer
lipid
amino acid
polymer
fatty acid
nucleic acid
carbohydrate
protein
MAIN IDEA: Carbon atoms have unique bonding properties.
Choose whether the statement is true or false.
1. true / false Carbon atoms form the building blocks of most living things.
2. true / false Carbon’s outer energy level is full.
3. true / false Carbon atoms can form covalent bonds with up to four other atoms.
4. true / false The three basic structures of carbon-based molecules are straight
chain, bent chain, and ring.
5. Choose one of the three basic structures of carbon-based molecules to sketch
in the space below. Label your sketch with the name of the basic structure.
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
8
Chemistry of Life
Section 3: Carbon-Based Molecules
Study Guide A continued
MAIN IDEA: Four main types of carbon-based molecules are found in living
things.
Complete the table with the functions and examples provided for each type of
carbon-based molecule.
Functions
Examples
Provide energy
meat
fat
oils
Source of Amino Acids
sugar
beans
DNA
Map for making proteins
RNA
starches
nuts
Store energy
Molecule Type
Functions
Examples
Carbohydrate
6.
7.
Lipid
8.
9.
Protein
10.
11.
Nucleic acid
12.
13.
Vocabulary Check
14. The prefix mono- means “one,” and the prefix poly- means “many.”
Which contains more molecules, a monomer or a polymer?
____________________
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
9
Chemistry of Life
Section 3: Carbon-Based Molecules
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
10
Chemistry of Life
Section 3: Carbon-Based Molecules