Question 1

Proteins

Accepted Answer

A)  are involved in almost every important function performed by a cell AND are characterized by a 1:3:1 ratio of carbon to hydrogen to oxygen. 
B)  comprise more than 50% of the dry weight of a cell AND are composed of a chain of nucleotides. 
C)  are involved in almost every important function performed by a cell AND comprise more than 50% of the dry weight of a cell. 
D)  are composed of a chain of amino acids AND are characterized by a 1:3:1 ratio of carbon to hydrogen and oxygen. 
E)  are characterized by a 1:2:1 ratio of carbon to hydrogen to oxygen AND are composed of a chain of nucleotides. 
A)  are involved in almost every important function performed by a cell AND are characterized by a 1:3:1 ratio of carbon to hydrogen to oxygen. 
B)  comprise more than 50% of the dry weight of a cell AND are composed of a chain of nucleotides. 
C)  are involved in almost every important function performed by a cell AND comprise more than 50% of the dry weight of a cell. 
D)  are composed of a chain of amino acids AND are characterized by a 1:3:1 ratio of carbon to hydrogen and oxygen. 
E)  are characterized by a 1:2:1 ratio of carbon to hydrogen to oxygen AND are composed of a chain of nucleotides.

Question 2

RNA is a long double-stranded helix containing ribose and uracil.

Accepted Answer

A) True 
 B)False

Question 3

Which of the following statements about enzymes is False?

Accepted Answer

A)  Enzymes are composed of amino acids. 
B)  Enzymes help break covalent bonds. 
C)  Enzymes position reactants so covalent bonds form more easily. 
D)  Enzymes are essential for maintaining life. 
E)  Enzymes increase the temperature of a reaction. 
A)  Enzymes are composed of amino acids. 
B)  Enzymes help break covalent bonds. 
C)  Enzymes position reactants so covalent bonds form more easily. 
D)  Enzymes are essential for maintaining life. 
E)  Enzymes increase the temperature of a reaction.

Question 4

The positively charged component of the atom is the

Accepted Answer

A)  electron. 
B)  neutron. 
C)  proton. 
D)  cation. 
E)  anion. 
A)  electron. 
B)  neutron. 
C)  proton. 
D)  cation. 
E)  anion.

Question 5

If the side chains of amino acids contain carboxyl (-COOH) groups, they

Accepted Answer

A)  contribute a positive charge to the amino acid at pH 10 AND are considered acidic amino acids. 
B)  contribute a negative charge to the amino acid at pH 10 AND are considered nucleic acids. 
C)  contribute a positive charge to the amino acid at pH 10 AND are considered nucleic acids. 
D)  contribute a negative charge to the amino acid at pH 10 AND are considered acidic amino acids. 
E)  contribute a negative charge to the amino acid at pH 10 AND are considered acidic monosaccharides. 
A)  contribute a positive charge to the amino acid at pH 10 AND are considered acidic amino acids. 
B)  contribute a negative charge to the amino acid at pH 10 AND are considered nucleic acids. 
C)  contribute a positive charge to the amino acid at pH 10 AND are considered nucleic acids. 
D)  contribute a negative charge to the amino acid at pH 10 AND are considered acidic amino acids. 
E)  contribute a negative charge to the amino acid at pH 10 AND are considered acidic monosaccharides.

Question 6

The purines of DNA are

Accepted Answer

A)  adenine and guanine. 
B)  thymine and adenine. 
C)  serine and threonine. 
D)  thymine and uracil. 
E)  thymine, adenine AND uracil. 
A)  adenine and guanine. 
B)  thymine and adenine. 
C)  serine and threonine. 
D)  thymine and uracil. 
E)  thymine, adenine AND uracil.

Question 7

Dan is a body builder. He decides that he is going to change his diet in an effort to increase his muscle mass. Dan tells you that he plans to eat vegetables and proteins but no fats or carbohydrates, because cells do not naturally contain these molecules and do not need them. You advise Dan that his new diet is not a good choice, and that he would do better to follow a well balanced diet that incorporates healthy amounts of proteins, fats AND carbohydrates.
-Dan asks you how his cells are able to use complex molecules such as proteins. You explain to him that proteins are macromolecules composed of ________ and that proteins can be broken down by ________, a type of reaction in which the addition of ________ breaks covalent bonds between subunits.

Accepted Answer

A)  water; hydrolysis; amino acids 
B)  amino acid; hydrolysis; water 
C)  monosaccharides; hydrolysis; water 
D)  amino acids; dehydration synthesis; water 
E)  monosaccharides; dehydration synthesis; water 
A)  water; hydrolysis; amino acids 
B)  amino acid; hydrolysis; water 
C)  monosaccharides; hydrolysis; water 
D)  amino acids; dehydration synthesis; water 
E)  monosaccharides; dehydration synthesis; water

Question 8

You are a biochemist working on a molecule found in a recently discovered bacterium. You determine that the molecule is composed of a chain of similar subunits and can thus conclude that the molecule is unlikely to be a

Accepted Answer

A)  lipid. 
B)  nucleic acid. 
C)  protein. 
D)  carbohydrate. 
E)  lipid or protein. 
A)  lipid. 
B)  nucleic acid. 
C)  protein. 
D)  carbohydrate. 
E)  lipid or protein.

Question 9

Water-soluble substances easily pass through the phospholipid bilayer of a cell membrane.

Accepted Answer

A) True 
 B)False

Question 10

Side chains are important to proteins because they

Accepted Answer

A)  help determine protein shape AND are a source of energy for hydration reactions in the cell. 
B)  help determine the degree of solubility of the protein in water. 
C)  are a source of energy for hydration reactions in the cell. 
D)  form the peptide bonds that link amino acids to one another. 
E)  help determine protein shape AND help determine the degree of solubility of the protein in water. 
A)  help determine protein shape AND are a source of energy for hydration reactions in the cell. 
B)  help determine the degree of solubility of the protein in water. 
C)  are a source of energy for hydration reactions in the cell. 
D)  form the peptide bonds that link amino acids to one another. 
E)  help determine protein shape AND help determine the degree of solubility of the protein in water.

Question 11

In general, when saturated fats are compared to unsaturated fats (assuming the same number of carbon atoms in the molecule),

Accepted Answer

A)  they have about the same melting temperature. 
B)  saturated fats have a lower melting temperature. 
C)  unsaturated fats have a lower melting temperature. 
D)  unsaturated fats have a higher melting temperature. 
E)  saturated fats are more liquid at room temperature. 
A)  they have about the same melting temperature. 
B)  saturated fats have a lower melting temperature. 
C)  unsaturated fats have a lower melting temperature. 
D)  unsaturated fats have a higher melting temperature. 
E)  saturated fats are more liquid at room temperature.

Question 12

Structural isomers

Accepted Answer

A)  contain the same number of atoms/elements, but in different arrangements AND may be referred to as the -D and -P forms. 
B)  are exemplified by glucose and galactose AND are formed by different arrangements of the -COOH groups 
C)  contain the same number of atoms/elements, but in different arrangements AND are exemplified by glucose and galactose. 
D)  are formed by different arrangements of the -COOH groups AND may be referred to as the -D and -L forms. 
E)  may be referred to as the -D and -P forms AND are exemplified by glucose and fructose. 
A)  contain the same number of atoms/elements, but in different arrangements AND may be referred to as the -D and -P forms. 
B)  are exemplified by glucose and galactose AND are formed by different arrangements of the -COOH groups 
C)  contain the same number of atoms/elements, but in different arrangements AND are exemplified by glucose and galactose. 
D)  are formed by different arrangements of the -COOH groups AND may be referred to as the -D and -L forms. 
E)  may be referred to as the -D and -P forms AND are exemplified by glucose and fructose.

Question 13

Amino acids that contain many methyl (-CH₃) groups

Accepted Answer

A)  are considered hydrophilic. 
B)  are nonpolar. 
C)  carry a positive charge. 
D)  carry a negative charge. 
E)  are considered hydrophilic AND carry a positive charge. 
A)  are considered hydrophilic. 
B)  are nonpolar. 
C)  carry a positive charge. 
D)  carry a negative charge. 
E)  are considered hydrophilic AND carry a positive charge.

Question 14

Amino acids in proteins are linked to one another by peptide bonds between the

Accepted Answer

A)  methyl group of one amino acid and a side group of another amino acid. 
B)  carbon atoms of two adjacent amino acids. 
C)  carboxyl group of one amino acid and the amino group of another. 
D)  nitrogen atom and carboxyl ion. 
E)  phosphate group and nitrogenous base. 
A)  methyl group of one amino acid and a side group of another amino acid. 
B)  carbon atoms of two adjacent amino acids. 
C)  carboxyl group of one amino acid and the amino group of another. 
D)  nitrogen atom and carboxyl ion. 
E)  phosphate group and nitrogenous base.

Question 15

You are working in a laboratory, making media for growing bacteria. The recipe you are following calls for the addition of TRIS buffer. You can't find any TRIS in the lab, so you decide to leave it out of the medium. Select the False statement regarding your decision.

Accepted Answer

A)  The medium will likely not be useable, because bacteria live within a narrow pH range, near pH 14. 
B)  Maintaining the correct pH is essential for cells, because crucial molecules such as enzymes may lose function in the incorrect pH. 
C)  Buffers are added to solutions to stabilize the hydrogen ion concentration of that solution. 
D)  The acidity of the medium without buffer may change dramatically as the bacteria grow. 
E)  The medium will likely not be useable, because bacteria live within a narrow pH range, near neutral. 
A)  The medium will likely not be useable, because bacteria live within a narrow pH range, near pH 14. 
B)  Maintaining the correct pH is essential for cells, because crucial molecules such as enzymes may lose function in the incorrect pH. 
C)  Buffers are added to solutions to stabilize the hydrogen ion concentration of that solution. 
D)  The acidity of the medium without buffer may change dramatically as the bacteria grow. 
E)  The medium will likely not be useable, because bacteria live within a narrow pH range, near neutral.

Question 16

A biologist determined the amounts of several amino acids in two separate samples of pure protein. His data showed that Protein A contained 7% leucine, 12% alanine, 4% histidine, 2% cysteine, and 5% glycine. Interestingly, Protein B had the same percentages of the same amino acids. He concluded from this data that Proteins A and B are the same protein. Based on this information and his conclusion, determine which of the following is the correct statement regarding his findings:

Accepted Answer

A)  He is correct; the proteins have the same percentages of each amino acid, so they are identical protein molecules. 
B)  He is incorrect;  there is no information about the amino acids sequence (which dictates the overall structure of a protein), so the two proteins could be very different in shape. 
C)  He is correct; although there is no information on the amino acid sequence in each protein, the order of the amino acids is irrelevant. It's only the total number of each molecule that is important to structure. 
D)  He is incorrect; he hasn't accounted at all for the effects of pH on the composition of the protein and its effects on the individual amino acids. 
E)  He is partly correct; the percentage of the listed amino acids is the same in each protein, but Protein A is hydrophobic and Protein B is hydrophilic. 
A)  He is correct; the proteins have the same percentages of each amino acid, so they are identical protein molecules. 
B)  He is incorrect;  there is no information about the amino acids sequence (which dictates the overall structure of a protein), so the two proteins could be very different in shape. 
C)  He is correct; although there is no information on the amino acid sequence in each protein, the order of the amino acids is irrelevant. It's only the total number of each molecule that is important to structure. 
D)  He is incorrect; he hasn't accounted at all for the effects of pH on the composition of the protein and its effects on the individual amino acids. 
E)  He is partly correct; the percentage of the listed amino acids is the same in each protein, but Protein A is hydrophobic and Protein B is hydrophilic.

Question 17

Simple lipids contain carbon, hydrogen, and oxygen in a 1:2:1 ratio.

Accepted Answer

A) True 
 B)False

Question 18

Water

Accepted Answer

A)  is a polar molecule. 
B)  is referred to as a universal solvent. 
C)  makes up over 70% of an organism. 
D)  is often a product or reactant in chemical reactions. 
E)  All of the answer choices are correct. 
A)  is a polar molecule. 
B)  is referred to as a universal solvent. 
C)  makes up over 70% of an organism. 
D)  is often a product or reactant in chemical reactions. 
E)  All of the answer choices are correct.

Question 19

Steroids are simple lipids.

Accepted Answer

A) True 
 B)False

Question 20

The most important feature of a protein is its

Accepted Answer

A)  secondary structure. 
B)  side group. 
C)  shape. 
D)  electric charge. 
E)  size. 
A)  secondary structure. 
B)  side group. 
C)  shape. 
D)  electric charge. 
E)  size.

Exam 2: The Molecules of Life

Proteins

RNA is a long double-stranded helix containing ribose and uracil.

Which of the following statements about enzymes is False?

The positively charged component of the atom is the

If the side chains of amino acids contain carboxyl (-COOH) groups, they

The purines of DNA are

You are a biochemist working on a molecule found in a recently discovered bacterium. You determine that the molecule is composed of a chain of similar subunits and can thus conclude that the molecule is unlikely to be a

Water-soluble substances easily pass through the phospholipid bilayer of a cell membrane.

Side chains are important to proteins because they

In general, when saturated fats are compared to unsaturated fats (assuming the same number of carbon atoms in the molecule),

Structural isomers

Amino acids that contain many methyl (-CH₃) groups

Amino acids in proteins are linked to one another by peptide bonds between the

You are working in a laboratory, making media for growing bacteria. The recipe you are following calls for the addition of TRIS buffer. You can't find any TRIS in the lab, so you decide to leave it out of the medium. Select the False statement regarding your decision.

Simple lipids contain carbon, hydrogen, and oxygen in a 1:2:1 ratio.

Water

Steroids are simple lipids.

The most important feature of a protein is its

Humans and the Microbial World

Microscopy and Cell Structure

Dynamics of Microbial Growth

Control of Microbial Growth

Microbial Metabolism: Fueling Cell Growth

The Blueprint of Life, from DNA to Protein

Bacterial Genetics

Biotechnology

Identifying and Classifying Microorganisms

The Diversity of Bacteria and Archaea

The Eukaryotic Members of the Microbial World

Viruses, Viroids, and Prions

The Innate Immune Response

The Adaptive Immune Response

Host-Microbe Interactions

Immunological Disorders

Applications of Immune Responses

Epidemiology

Antimicrobial Medications

Respiratory System Infections

Skin Infections

Wound Infections

Digestive System Infections

Blood and Lymphatic Infections

Nervous System Infections

Genitourinary Tract Infections

Microbial Ecology

Environmental Microbiology: Treatment of Water, Wastes, and Polluted Habitats

Food Microbiology

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