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Bio 12
Chapter 2 Test Review
1.Know the difference between ionic and covalent bonds
In order to complete outer shells in electrons bonds can be
Ionic; one atom donates or receives electrons
Covalent; atoms share electrons
2. Know what a polar covalent bond is:
bond that has UNEQUAL sharing of electrons
3. Be able to explain why water is a polar molecule
*Polar bonds have charges on either end and often attract to each other
*Atoms ‘hogging’ the electrons have an electronegative charge, and atoms
‘lacking’ electrons have an electropositive charge
4. Explain what a hydrogen bond is and why it is important
Electronegative atoms on one molecule are attracted to electropositive atoms
on a different molecule. Form Hydrogen bonds.
5. Explain the unique characteristics of water and explain how they are useful
to organisms (poster you made)
*Water molecules are attracted to other polar molecules
cohesion – when one water molecule is attracted to another water molecule
adhesion – when polar molecules other than water stick to a water molecule (Steady
column of water)
*Water warms up and cools down slowly (high heat capacity)
*Water has a high heat of vaporization because so many hydrogen bonds must be
broken for water to evaporate
*A solution consists of a solute dissolved into a solvent
*Water’s hydrogen bonds help it dissolve other polar molecules
*Frozen Water is Less Dense than Liquid Water and floats on liquid water
6. Explain the difference between an acid and a base and what pH is.
pH is the Measurement of Acidity (acid) or Alkalinity (base) of a Solution.
The pH scale goes from 0 to 14
- pH 0 is acidic
- pH 7 is neutral
- pH 14 is basic
The greater the H+ concentration,
the lower the pH
The lower the hydrogen ion concentration, the higher the pH
7. Define buffer and explain its role in biological systems
Buffers Help Keep the pH of Body Fluids Relatively Constant
Buffer System: the combination of a weak acid and the base that forms when the
acid dissolves in water
By binding or releasing H+’s, it maintains a constant concentration of free H+’s in the
solution
8. Explain how differences in carbon skeleton and attached functional groups
cause organic molecules to have different chemical properties
A hydrocarbon chain can turn back on itself to form a ring compound, or a spiral or
a series of folds due to the interaction between the atoms and the functional groups.
Functional groups are specific combinations of bonded atoms that always react in
the same way.
9. Explain the difference between hydrophobic and hydrophilic
 Hydrophilic (water-loving) molecules form hydrogen bonds with water
 Hydrophobic (water-fearing) molecules do not form hydrogen bonds with
water
10. Differentiate between the four classes of macromolecules and be able to
identify them from a picture of their structure
1) Carbohydrates
monomer
polymer (Chitin)
2) Proteins
3) Lipids
Which Is a Source of Unsaturated Fatty Acids?
Linseed Oil
Beef Fat
Est
4) Nucleic Acids
P
P
P
11. Explain the relationship between monomers and polymers of the
macromolecules (glucose vs starch, amino acids and proteins…)
Monomer or building blocks
polymer
glucose
Starch, cellulose or glycogen, chitin
Amino acid
proteins
Glycerol and fatty acids
Lipids (also Steroids, Waxes)
Nucleotides (sugar, phosphate group and DNA, RNA, ATP
nitrogenous base)
12. Differentiate between dehydration synthesis and hydrolysis and make
sure to understand whether water is added or removed and whether energy is
released or required in the reaction
By taking out a water molecule (hydroxyl-OH from one and Hydrogen-H from
another monomer) between building blocks, you can link monomers or building
blocks to make a larger molecule (polymer). This is called dehydration
synthesis.Energy is required (endergonic)
By adding a water molecule, you can cut the larger polymer into its individual
monomers or building block components. This is called hydrolysis (water cutting).
Energy is given off (exergonic)
13. Know the difference between glycogen and cellulose
Glucose converts to a long-chain carbohydrate, Glycogen, to store in the liver, in
animals.
Glucose converts into a long-chain carbohydrate, cellulose, to store in the cell walls
of plants that give it structural support.
14. Explain why fats and oils are insoluble in water
Both fats and oils are hydrophobic. That is, they do not attract water since there is
no – or + end. They are non-polar.
15. What is the difference between saturated and unsaturated fatty acids?
Saturated fats contain no double bonds between the carbons in the chain of the fatty
acid.
Unsaturated fats contain double bonds between the carbons. KINKY!! Fluid as a
result of the space created between the chains as a result of the kinks.
16. Distinguish between phospholipids and triglycerides
Triglycerides have a glycerol backbone and three fatty acid chains attached (FAT)
Phospholipids have a glycerol backbone and TWO fatty acid chains and a phosphate
group
17. What are waxes? What are steroids?
Waxes: lipids that protect from water (plants, ears)and energy storage in plankton;
long chain fatty acid attached to an alcohol, solid at room temperature
Steroids: lipids that are fused carbon rings that can be hormones (chemical
messengers in the body) or structural units (cholesterol is a part of the cell
membrane)
18. Be able to draw and label the parts of the phospholipid bilayer
Lipids: Structure
•Phospholipid—component of cell membranes
Polar
Head
Glycerol
Hydrophilic
Fatty Acid Tails
Hydrophobic
19. Know the different tests one can use to determine if there is a presence of
proteins, simple sugars or complex sugars (LAB)
+ for Simple sugars (like glucose): benedict’s solution (turns from peacock blue to
orange or brick red)
+ for Complex sugars (like starch): Lugol’s IODINE (orange) turns the substance
black
+ for Proteins (like meat): Biuret’s solution turns violet
Do these questions:
Multiple choice questions #1-39 just the number and letter answer (do
corrections afterwards in a different colour and explain the correction)
Short Answer questions: #43, 44, 46, 47, 49, 51-54, 55-57, 59, 60, 62, 63, 68,
72, 77, 79, 81 (do corrections afterwards in a different colour and explain the
correction)
Short Answer questions
43) The strong acid hydrogen chloride can be dissolved in water. The pH will decrease and cause
the solution to be more acidic due to the release of hydrogen ions.
44) Bond X is a hydrogen bond.
46) Functions: acts as a solvent by dissolving substances, acts as a lubricant by lubricating joints,
acts as a temperature regulator for body heat.
47) The electronegativity of the covalent bond causes the shared electron pair to spend more
time around the nucleus of the oxygen atom than that of the hydrogen atom in a water molecule.
This creates a slightly negative charge on the oxygen atom and slightly positive charges on the
hydrogen atoms resulting in an unequal sharing of electrons and a polar covalent bond.
49) Runners eat meals with large quantities of carbohydrates a few days before a marathon
because it provides quick fuel and short-term energy storage. The body will store the
carbohydrates needed for the race and on the day of the race, glycogen will be converted into
glucose so that glucose can be used to produce ATP during cellular respiration.
51) Dehydration synthesis is illustrated in the diagram. It shows the removal of a hydroxyl group
of one amino acid and the hydrogen atom of the second amino acid, the equivalent of water, to
allow the combining of the two into a dipeptide.
52) Bond X is a peptide bond.
53) A dipeptide and a water molecule will form as a result of this reaction.
54) 9 molecules of water will be produced if 10 amino acids are linked
55) Lactose is classified as a disaccharide that belongs to the carbohydrate family.
56) Water is required.
57) Hydrolysis is illustrated in the diagram.
59) a. The base sequences of specific sections of DNA contain a code that specifies the
sequence of amino acids in the proteins of the cell.
b. Nucleic acids are polymers of nucleotide monomers.
c. A monosaccharide only has one sugar molecule whereas a polysaccharide contains many
sugar molecules.
d. A polypeptide is made up of amino acids joined together by peptide bonds.
e. In the secondary structure of a protein, hydrogen bonding between the amino acids causes the
polypeptide to form an alpha helix or a beta pleated sheet.
f. The polarity in water molecules allows it stick together or cohesion to occur. Unequal sharing of
electrons in water.
60) a. A glycerol has three carbon atoms, each of which has a hydroxyl (-OH) group bound to it.
b. A triglyceride has three fatty acids attached to glycerol whereas a phospholipid has a
phosphate group that replaces one of the fatty acids.
c. A peptide bond forms between carboxyl group and the nitrogen of the amino group in a
dipeptide. A hydrogen bond forms between different amino acids in the polypeptide chain.
d. An unsaturated fatty acid has a double bond meaning it has one less hydrogen atom than a
saturated fatty acid.
62) The positive result of both the disaccharide maltose and the monosaccharide glucose means
there is a presence of sugar. It must have been positive because the monosaccharide glucose
makes up maltose when two combine.
63) When a mixture of phospholipids and water is shaken, the phospholipids spontaneously
assemble in vesicles surrounded by a lipid bilayer because the their polar heads are hydrophilic
and their non polar tails are hydrophobic.
68) This is a change in the primary structure of the polypeptide chain as this is where a certain
orientation is taken on. The hydrogen bonding between the altered sequence of amino acids will
change the shape causing the tertiary and quaternary to also be affected as these are later
stages in the protein organization where more bonding occurs.
72) Proteins are more structurally and functionally diverse than carbohydrates because the
variety in its R group allows for a uniqueness in each amino acid.
77)
CELLULOSE
STARCH
GLYCOGEN
Monomer
Glucose
Glucose
Glucose
Description of Structure
No side chains
Less side chains
More side branches
(chains of glucose) that
branch off from the main
chain than starch
Plant or Animal Cell
plant
plant
animal
Function
Structural support in plants Long term storage in
plants
Long term storage in
animals
Characteristic
DNA
RNA
PROTEIN
Polymer?
Yes
Yes
Yes
3-D Structure?
Yes
Yes
Yes
Contain nitrogen atoms?
Yes
Yes
Yes
Phosphorus atoms?
Yes
Yes
No
Hydrogen bonding?
Yes
No - YES
Yes
79)
81) Protein organization bonding:
a. primary – peptide bonds
b. secondary – hydrogen bonding
c. tertiary – covalent bonding
d. quaternary – bond between 2 or more polypeptides