Microbiology with Diseases by Body System, 5e (Bauman)
Chapter 2 The Chemistry of Microbiology
2.1 Multiple Choice Questions
1) Which of the following is an atomic particle that has no electrical charge?
A) electron
B) neutron
C) element
D) proton
E) isotope
2) Matter composed of a single type of atom is known as a(n)
A) element.
B) mineral.
C) molecule.
D) compound.
E) electron.
3) A stable atom has ________ in its valence shell.
A) 4 electrons
B) 2 neutrons
C) 8 electrons
D) 8 protons
E) 10 electrons
4) Which parts of the atoms interact in a chemical reaction?
A) protons
B) neutrons
C) ions
D) electrons
E) isotopes
5)
The atomic mass of this stable isotope atom (Figure 2.1) is
A) 4.
B) 6.
C) 10.
D) 12.
E) cannot be determined from the available information
6) The number of ________ of an element determines its atomic number.
A) protons
B) neutrons
C) electrons
D) valence electrons
E) isotopes
7) The type(s) of bond(s) produced when atoms share electrons equally is/are
A) a nonpolar covalent bond.
B) a hydrogen bond.
C) an ionic bond.
D) a polar covalent bond.
E) both polar covalent and ionic bonds.
8) The type(s) of bond(s) produced when atoms with somewhat different electronegativities
share electrons is/are
A) a nonpolar covalent bond.
B) a polar covalent bond.
C) an ionic bond.
D) a hydrogen bond.
E) both nonpolar covalent and ionic bonds.
9) The carbon atoms in organic compounds typically form ________ with other atoms.
A) nonpolar covalent bonds
B) polar covalent bonds
C) ionic bonds
D) hydrogen bonds
E) either ionic or hydrogen bonds
10) Unstable isotopes can be useful
A) catalysts.
B) in medical diagnosis.
C) in vitamins.
D) in the formation of hydrogen bonds.
E) as buffers.
11) Which of the following is an INCORRECT pairing?
A) electrolytes; anions
B) synthesis; endothermic
C) hydrolysis; hydrogen bonds
D) catabolism; exothermic
E) dehydration; anabolism
12) The chemical formula of the oxygen we require is O2. It is
A) a compound.
B) an isotope.
C) an element.
D) a molecule.
E) both an element and a molecule.
13) Which of the following is a property of water?
A) It has a high capacity for heat.
B) It is not a common reactant in metabolic reactions.
C) It is not a good solvent.
D) It is liquid in a very narrow temperature range.
E) It is a nonpolar molecule.
14) An acid dissociates in water to release
A) hydrogen ion(s).
B) cation(s).
C) hydroxyl group(s).
D) anion(s).
E) both anions and hydrogen ions.
15) The reverse of a dehydration synthesis reaction is a(n) ________ reaction.
A) anabolic
B) exchange
C) hydrolytic
D) endothermic
E) metabolic
16) A weak acid may function as a
A) transfer group.
B) buffer.
C) hydroxyl donor.
D) cation.
E) salt.
17) Which of the following is NOT a characteristic of saturated fats?
A) They are usually solid at room temperature.
B) They contain at least one double bond.
C) They are found in animals.
D) Their fatty acids pack tightly together.
E) They are a form of stored energy.
18) Which of the following is NOT a characteristic of phospholipids?
A) They are found in cellular membranes.
B) They can form micelles and bilayers.
C) They contain fatty acids that associate with water.
D) They contain a hydrophilic phosphate “head.”
E) They contain two fatty acids and a phosphate functional group.
19) Organisms use carbohydrates in all of the following ways EXCEPT
A) as a component of cell walls.
B) as a long-term energy source.
C) as a short-term energy source.
D) to keep membranes flexible at low temperatures.
E) as a building block of DNA and RNA molecules.
20) Nucleic acids, proteins, and complex carbohydrates are all produced by
A) hydrolytic reactions.
B) dehydration synthesis.
C) exchange reactions.
D) hydrogen bonding.
E) catabolic reactions.
21) Which of the following is an example of a polysaccharide?
A) glycogen
B) glucose
C) fructose
D) deoxyribose
E) sucrose
22) Which of the following statements about proteins is FALSE?
A) They are composed of amino acids.
B) They have multiple levels of structural organization.
C) They can be hydrophobic, hydrophilic, or both.
D) Their primary function is energy storage.
E) They are formed by dehydration synthesis reactions.
23) All of the following are components of an amino acid EXCEPT a(n)
A) carboxyl group.
B) pentose group.
C) amino group.
D) α-carbon.
E) R group.
24) Which of the following is found in nucleic acids?
A) amines
B) carboxylic acid
C) purines
D) glycerol
E) R group
25) Hydrogen bonds are found in all of the following EXCEPT
A) between phosphates in ATP.
B) in α-helices.
C) between water molecules.
D) in the DNA double helix between nucleotides.
E) between the R groups of amino acids in proteins.
26) Tertiary and quaternary structure of proteins involves ________ bonds.
A) hydrogen
B) ionic
C) polar covalent
D) nonpolar covalent
E) ionic, hydrogen, polar, and nonpolar covalent
27) All amino acids contain what functional group(s)?
A) aldehyde
B) amino
C) ester
D) carboxyl
E) both amino and carboxyl
28) All of the following bases are found in RNA molecules EXCEPT
A) adenine.
B) thymine.
C) uracil.
D) cytosine.
E) guanine.
29) The double-strands of DNA result from the formation of ________ between the bases.
A) covalent bonds
B) peptide bonds
C) ionic bonds
D) hydrogen bonds
E) α−1,4 bonds
30) Which of the following would NOT normally be found as a component of a cell’s nucleic
acids?
A) adenine deoxyribonucleotides
B) thymine deoxyribonucleotides
C) uracil deoxyribonucleotides
D) cytosine ribonucleotides
E) adenine ribonucleotides
31) Which of the following is an accurate description of ATP?
A) ATP is a form of long term energy storage.
B) ATP is a compound formed of ionic bonds.
C) ATP does not readily react with other cellular macromolecules.
D) ATP serves as a recyclable energy for cells.
E) ATP is a structural component of DNA.
32) Which of the following is NOT characteristic of RNA?
A) It is a helical polymer.
B) It is usually double-stranded.
C) Its “backbone” is composed of pentoses and phosphates.
D) It contains both purines and pyrimidines.
E) It can function as a catalyst.
33) Which of the following is an INCORRECT pairing?
A) primary structure; amino acid sequence
B) secondary structure; disulfide bridges
C) tertiary structure; covalent bonds
D) quaternary structure; two or more polypeptides
E) secondary structure; β-pleated sheets
34) Proteins contain both acidic and basic R groups and can, therefore, function as
A) energy storage macromolecules.
B) structural macromolecules.
C) buffers.
D) catalysts.
E) genetic material.
35) A(n) ________ is a compound that dissolves into anions and cations in water.
A) acid
B) buffer
C) base
D) salt
E) catalyst
36) Cell walls containing ________ provide the best protection from drying.
A) polysaccharides
B) triglycerides
C) waxes
D) peptidoglycan
E) sterols
37) A(n) ________ is an arrangement of atoms found in a variety of macromolecules.
A) buffer
B) isotope
C) salt
D) stereoisomer
E) functional group
38) Synthesis reactions are commonly ________ reactions.
A) endothermic
B) exchange
C) exothermic
D) anabolic
E) hydrolytic
39) Lipids found in the cytoplasmic membranes of all eukaryotic cells are
A) polyunsaturated fats.
B) phospholipids.
C) steroids.
D) waxes.
E) triglycerides.
40) A protein is a ________ of amino acids.
A) monomer
B) polymer
C) bilayer
D) solution
E) decomposition product
41) DNA is composed of repeating units of sugars, phosphates, and nucleic acids. This is an
example of a
A) polymer.
B) monomer.
C) salt.
D) micelle.
E) lipid.
42) An unbranched polymer composed of simple sugars is a(n)
A) protein.
B) triglyceride.
C) starch.
D) glycoprotein.
E) amino acid.
43) Anna is conducting an experiment using a pH indicator that is red at low pH, green at neutral
pH and purple at high pH. She starts with a green solution. When she adds compound X to her
solution it turns purple. Then she adds compound Z to the solution and it turns green. She adds
more Z, the solution remains green. These observations suggest X is ________ and Z is
________.
A) a base; a buffer
B) an acid; a base
C) a base; a strong acid
D) an acid; a buffer
E) a buffer; a base
44) A reaction requires water as a reactant and produces heat. What type of reaction is likely to
be involved?
A) an endothermic reaction
B) a dehydration reaction
C) an exchange reaction
D) a synthesis reaction
E) The answer cannot be determined from the available information.
45) Which of the following is an organic compound?
A) adenine
B) carbon dioxide
C) molecular oxygen
D) sodium chloride
E) water
46) Which of the following is found in RNA but not DNA?
A) adenine
B) cytosine
C) deoxyribose
D) guanine
E) uracil
1) The smallest chemical units of matter are elements.
2) The side groups of amino acids can interact with each other and with other molecules.
3) A molecule composed of carbon and hydrogen is a compound.
4) The electron shells of atoms hold eight electrons each.
5) Hydrogen bonds are stronger than covalent bonds.
6) A nucleotide with a single cyclic ring structure is a pyrimidine.
7) Denaturation of a protein is always permanent.
8) The valence of an atom is determined by the total number of electrons it contains.
9) Dehydration synthesis is a common feature of polymer production in cells.
10) Salts are produced from exchange reactions in which acids and bases neutralize each other.
1) Radioactive iodine is sometimes used to treat thyroid cancer. This is an example of the use of
(isotopes/elements/ isomers) in medical treatment.
2) A(n) (nonpolar/polar/ionic/hydrogen) bond is one in which electrons are shared equally
between atoms.
3) Cell surface markers composed of both carbohydrate and lipid molecules are known as
(glycoproteins/glycolipids/LPS).
4) An atom or molecule becomes a(n) (anion/ion/cation) when it loses an electron to a more
electronegative molecule.
5) A chemical reaction in which a water molecule is a reactant is known as a
(dehydration/endothermic/hydrolysis) reaction.
6) When a base dissolves in water it releases a(n) (electron/cation/hydrogen ion).
7) The folding of a polypeptide into a three-dimensional shape is its
(secondary/tertiary/quaternary) structure.
8) The DNA double helix is held together by (covalent/ionic/hydrogen) bonds.
9)
Figure 2.2 depicts the (primary/secondary/tertiary) structure of a protein.
10) A(n) (catalyst/enzyme) is any molecule that speeds up a chemical reaction.
11) The monomer of a nucleic acid is called a (nucleoside/nucleotide/base).
12) A nitrogenous base composed of two rings is a (purine/pyrimidine/ribose).
13) Jim adds an acid to a solution, but finds the pH has not changed afterward. This suggests the
solution contains a(n) (anion/buffer/salt).
14) A saturated fatty acid contains (no/one/multiple) double bonds.
15) The isotopes of an element vary in the number of (electrons/neutrons/protons) in the atom.
2.4 Essay Questions
1) Compare and contrast synthesis reactions with decomposition reactions.
2) Discuss the importance of hydrogen bonds in the chemistry of the cell.
3) Max is exploring the properties of various compounds. Some of his explorations involve the
use of a pH indicator that is red at low pH, yellow-green at neutral pH and blue to purple at high
pH. He sets up several tubes containing water and the pH indicator and then begins to add some
of the compounds (L, M, and N) he is characterizing in various combinations. His results are
shown on the following table.
What can Max conclude about his compounds based on these results? Describe the likely events
in terms of hydrogen and hydroxyl ions.
4) Describe the chemical properties of phospholipids that account for their behavior in water.
5)
Consider the structure of thymine, shown on the left in Figure 2.3 above, and compare to the
structure of pyrimidine X on the right. What would be the impact if X is incorporated into the
structure of a DNA strand in place of thymine?