Download Name: ____________ Pd.: ______ Date: Read Section 2.1 – Atoms

Name: _____________________________________________________ Pd.: ________ Date: ______________________
Study Guide – Biochemistry, Part I
Read Section 2.1 – Atoms, Ions, and Molecules, and answer the following questions:
1. __atoms________: The smallest basic unit of matter
2. Atoms consist of three types of smaller particles, called subatomic particles. They are:
_____protons_______________ - positive charge
_________neutrons__________ - neutral charge
__________electrons__________ - negative charge
3. The nucleus of an atom is made up of the ____protons__________ and _______neutrons_______.
4. Because an atom has equal numbers of positively charged ___protons__________ and negatively charged
_______electrons________, it is electrically neutral.
5. ______element________: One particular type of atom which cannot be broken down into a simpler
substance by ordinary chemical means. It also refers to a group of atoms of the same type.
6. Atoms of different elements differ in the number of _______protons_______ they have.
7. The chemical properties of an element are determined by the _______electrons___________.
8. Electrons move around the nucleus of an atom in regions called energy levels. Different energy levels can
hold different numbers of electrons. The first energy level can hold __2__ electrons, and the second energy
level can hold ___8__ electrons. Atoms are most stable when they have a full outermost energy level.
9. The four elements that make up 96 percent of the human body’s mass are
_________carbon_____________
___________hydrogen_______
________oxygen______________
_______nitrogen_______________
10. Elements found in very small amounts in the body but which are needed to survive are called
______trace________ elements. For example, iron (Fe) is needed to transport oxygen in your blood.
Chromium (Cr) is needed for your cells to break down sugars for usable energy.
11. __compound_________________: A substance made of atoms of different elements bonded together in a
certain ratio.
12. ___isotope________________: An atom that has gained or lost one or more electrons.
13. __ionic_________________: A bond formed through the electrical force between oppositely charged ions.
14. _____covalent______________: A bond formed when atoms share a pair of electrons. These bonds are
generally very strong.
15. _molecule__________________: Two or more atoms held together by covalent bonds
Read Section 2.2 – Properties of Water, and answer the following questions:
16. Unlike most substances, water __expands______________ as it freezes. Water is therefore [less] [more]
dense as a solid (ice) than as a liquid.
17. Water molecules have a region with a slight positive charge and a region with a slight negative charge. This
water a _____polar___________ molecule.
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18. Opposite charges of polar molecules can interact to form ___hydrogen___________ bonds. These bonds are
an attraction between a slightly positive hydrogen atom and a slightly negative atom, often oxygen or
nitrogen.
19. Hydrogen bonds are responsible for three important properties of water: high specific heat, cohesion,
adhesion
STUDY GUIDE – BIOCHEMISTRY, PART II
Section 2.3
1. All organic compounds contain the element ____compound_______________.
2. Circle the item below which is NOT an organic macromolecule:
Carbohydrate
ice
lipid
nucleic acid
3. Identify each of the following as primarily a carbohydrate, lipid, protein, or nucleic acid.
___carbohydrate_____ Sugars
_______nucleic acid______ DNA
____lipid_____ waxes
_________protein_________ meat
__ carbohydrate ___ bread
__________nucleic acid________ RNA
____lipid_________ cholesterol
______lipid____ fats
4. The two types of nucleic acids are ______DNA_________ and _______RNA_______.
5. Which type of organic biological macromolecule do each of the following food products primarily contain:
____carbohydrate_______
_____lipid______
___nucleic acid_______
______protein________
6. Circle the item below which is NOT a lipid:
Saturated fats
starch
cholesterol
earwax
7. A typical can of soda contains a large amount of sugar. Therefore, sodas are high in _______carbohydrates_______.
8. An athlete who wants to build muscle mass would most likely choose a diet high in ______protein____________.
9. An athlete preparing to run a long-distance marathon would most likely choose a meal before the event that was high
in ____lipids_________.
10. Name the macromolecule that is composed of each of the following subunits:
Amino acids ______protein_____________
Sugar molecules ____carbohydrate___________
Fatty acids _______lipid______________
Nucleotides______nucleic_acid__
The molecule shown here is a
monomer of one of the four
biological macromolecules. It
is a(n)
________protein______
Starches __carbohydrate_______________
11. The diagram to the left is a monomer of ____nucleic acid________.
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Section 2.4
12. Substances are changed into different substances by _____chemical reaction__________.
13. Which organic biological macromolecule is the main source of energy for living things? _____carbohydrates____.
14. Which biological macromolecule is responsible for the genetic inheritance of physical traits? ___nucleic acids_______
15. Identify the reactants in the following chemical reaction: 6H 2O + 6CO2
C6H12O6 + 6O2
__________6H2O + 6CO2 ___________
Identify the products of the above chemical reaction: _____________ C6H12O6 + 6O2________________
16. What is the term for the amount of energy that needs to be added for a chemical reaction to start?
________activation energy____________
17. Match the following terms:
a. exothermic reaction
__G_ the subunit of a polymer
b. endothermic reaction
__H_ large compound formed by the joining of small compounds (monomers)
c. catalyst
__C_ substance that decreases activation energy and increases reaction rate
d. activation energy
__D_ energy input necessary to start a chemical reaction
e. enzyme
__E_ a protein that catalyzes (speeds up) chemical reactions for organisms
f. chemical reaction
__F_ process that produces a new set of chemicals
g. monomer
__B_ a chemical reaction that absorbs energy
h. polymer
__A_ a chemical reaction that releases energy
Section 2.5
18. Which statement best describes the graph shown here?
a. more energy is released by the original reaction
b. less energy is needed to start reaction B
c. the original reaction is catalyzed
d. reaction B occurs at a slower rate
A ____exothermic_____
B __endothermic________
19. Label each of the diagrams above as an exothermic or endothermic reaction.
20. What does the letter “B” represent in each of the diagrams? ______activation energy_________
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21. In each of the diagrams above, the letter “A” represents the ___reactants______ of the chemical reaction and the
letter “B” represents the _activation energy_______ of the chemical reaction.
22. In the diagram of a chemical reaction to the left, which reaction pathway
requires the least activation energy? ___C____
23. Most enzymes are
a. carbohydrates
b. lipids
c. nucleic acids
d. proteins
24. Enzymes affect chemical reactions in living organisms by
a. changing the direction of a reaction
b. breaking down molecules into starch
c. increasing the temperature range
d. weakening bonds in all reactants
25. The specific reactants that an enzyme acts on are called
a. catalysts
b. proteins
c. substrates
d. amino acids
26. Changes in temperature and pH can decrease an enzyme’s activity by breaking
a. hydrogen bonds
b. peptide bonds
c. amino acids
d. sulfur-sulfur bonds
27. An animal’s stomach contains enzymes that break down food into smaller molecules that the animal’s cells can use.
Enzymes perform this function by
a. participating in chemical reactions
b. increasing the temperatuire
c. changing the ionic concentration
d. lowering the pH
28. Match the following terms:
a. amino acid
_D__ dissolved compound that prevents sharp swings in pH
b. monosaccharide
_C__ atoms of the same element that differ in the number of neutrons
c. isotopes
_A__ monomer of a protein
d. buffer
_G__ the reactant in a chemical reaction upon which an enzyme acts
e. nucleic acid
_B__ single sugar molecule
f. bond energy
_F__ the amount of energy needed to break a bond
g. substrate
_E__ stores and transmits genetic information
h. equilibrium
_H__ a condition in which reactants and products in a chemical reaction are formed at
the same rate
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