Deck 1: Biochemistry: An Evolving Science

Question 1

Which of the following is considered a metabolite,a substance that is chemically transformed in a biochemical process?

A) deoxyribonucleic acid
B) glycerol
C) protein
D) ribonucleic acid
E) polysaccharide

Answer 1

B

Question 2

The matter within a defined region of space is referred to as the _____.

A) universe
B) system
C) outer space
D) wormhole
E) None of the answers is correct.

Answer 2

B

Question 3

Which of the following are the strongest bonds in molecules?

A) covalent bonds
B) ionic bonds
C) hydrogen bonds
D) metallic bonds
E) None of the answers is correct.

Answer 3

A

Question 4

If the whole chain is used in a nonoverlapping frame,how many amino acids are defined by this DNA sequence: ATGTTTGGACTA?

A) two
B) three
C) four
D) six
E) twelve

Question 5

The fundamental groups of organisms include Eukarya,Bacteria,and _____.

A) Plantae
B) Animalia
C) Protista
D) Archaea
E) Fungi

Question 6

The term _____ is used to indicate Gibbs free energy.

A) $\Delta$ H
B) $\Delta$ E
C) $\Delta$ S
D) $\Delta$ G
E) $\Delta$ T

Question 7

The number of hydrogen bonds formed between G and C is _____.

A) 1
B) 2
C) 3
D) 4
E) 2 if in RNA, 3 if in DNA

Question 8

DNA is made from the building blocks adenine,guanine,cytosine and _____.

A) uridine
B) thymine
C) inosine
D) ribose
E) None of the answers is correct.

Question 9

What is the [H⁺] concentration in a urine sample that has a pH of 6?

A) 10^-6 M
B) 10^-8 M
C) 10⁶ M
D) 10^-14 M
E) 6 M

Question 10

What gives proteins such a dominant role in biochemistry?

A) the rigidity of the peptide backbone
B) the ability to act as a blueprint
C) the ability to self-replicate
D) the ability to spontaneously fold into complex three-dimensional structures
E) All of the answers are correct.

Question 11

Which is the correct order of decreasing bond strengths?

A) hydrogen bonds, covalent bonds, van der Waals interactions
B) hydrogen bonds, electrostatic interactions, covalent bonds
C) van der Waals interactions, covalent bonds, hydrogen bonds
D) covalent bonds, hydrogen bonds, van der Waals interactions
E) hydrophobic interactions, hydrogen bonds, electrostatic interactions

Question 12

Which of the following is a hydrogen bond donor?

A) the N in N-H D
B) the H in S-H
C) the O in P-O
D) the H in O-H
E) None of the answers is correct.

Question 13

The number of hydrogen bonds formed between A and T is _____.

A) 1
B) 2
C) 3
D) 4
E) 2 if in DNA, 3 if in RNA

Question 14

Which of the following describes the relationship between the strengths of hydrogen and covalent bonds?

A) Hydrogen bonds are always stronger than covalent bonds.
B) Hydrogen bonds and covalent bonds have equivalent strength.
C) Hydrogen bonds are always weaker than covalent bonds.
D) With a few exceptions, most hydrogen bonds are stronger than covalent bonds.
E) With a few exceptions, most covalent bonds are stronger than hydrogen bonds.

Question 15

The DNA backbone is made from repeating _____.

A) monosaccharide units
B) amino acid units
C) sugar-phosphate units
D) fatty acid
E) None of the answers is correct.

Question 16

What did Watson and Crick suggest to be significant about the base pairing found in the helix?

A) It allowed the DNA to twist in a helix.
B) The DNA could be circular.
C) It was a mechanism for copying.
D) All of the answers are correct.
E) None of the answers is correct.

Question 17

The energies for hydrogen bonds are approximately

A) 400 kJ mol^-1.
B) 100-240 kJ mol^-1.
C) 4-20 kJ mol^-1.
D) 200 kJ mol^-1.
E) None of the answers is correct.

Question 18

Approximately what percentage of the human genome encodes proteins?

A) 50%
B) 90%
C) 20%
D) 3%
E) None of the answers is correct.

Question 19

The structure of DNA described by Watson and Crick included

A) a double helix.
B) the sugar phosphate backbone aligned in the center of the helix.
C) the base pairs that are stacked on the inside of the double helix.
D) both a double helix and the sugar phosphate backbone aligned in the center of the helix
E) a double helix and the base pairs that are stacked on the inside of the double helix

Question 20

For a spontaneous reaction,the $\Delta$ G must be _____.

A) positive
B) negative
C) greater than 1
D) between 1 and 0
E) 0

Question 21

What is the significance of hydrogen bonding in biochemical structures such as DNA?

Question 22

Why does DNA denature when the pH is raised above 9?

A) Protons dissociate from guanine bases disrupting the hydrogen bonding to the other strand.
B) Protons bind to guanine residues giving them additional positive charges which disrupt the hydrogen bonding to the other strand.
C) Protons bind to functional groups that serve as hydrogen-bond acceptors, thus disrupting the hydrogen bonding to the other strand.
D) Protons dissociate from the phosphate groups in the backbone, which disrupts the hydrogen-bonding pattern between strands.
E) None of the answers is correct.

Question 23

The Second Law of Thermodynamics states

A) the total entropy of a system and its surroundings always increases for a spontaneous process.
B) temperatures will always decrease in a spontaneous process.
C) the total energy of a system and its surroundings is constant.
D) diversity is the result of gradual evolution.
E) None of the answers is correct.

Question 24

Typical van der Waals energies are about

A) 4-20 kJ mol^-1.
B) 2-4 kJ mol^-1.
C) 200 kJ mol^-1.
D) 500-1000 kJ mol^-1.
E) None of the answers is correct.

Question 25

Entropy is defined as

A) a spontaneous reaction.
B) the enthalpy of the system.
C) the measure of randomness of a system.
D) the amount of heat exchanged.
E) None of the answers is correct.

Question 26

The First Law of Thermodynamics states

A) diversity is the result of gradual evolution.
B) the total entropy of a system and its surroundings always increases for a spontaneous process.
C) the total energy of a system and its surroundings is constant.
D) light is both particle and wave.
E) None of the answers is correct.

Question 27

What is the [A^-]/[HA] ratio when a weak acid is in a solution one pH unit below its pK_a?

A) 1:1
B) 1:10
C) 10:1
D) 2:1
E) None of the answers is correct.

Question 28

Which of the following atoms commonly found in biological molecules are often hydrogen-bond acceptors?

A) carbon
B) oxygen
C) nitrogen
D) All of the answers are correct.
E) oxygen and nitrogen

Question 29

The simplest way to depict stereochemistry is to use

A) ball-and-stick models.
B) ribbon diagrams.
C) space-filling models.
D) Fisher projections.
E) None of the answers is correct.

Question 30

Using the Henderson-Hasselbalch equation,calculate the pH of a buffer solution made from 0.20 M CH₃COOH and 0.050 M CH₃COO^- that has pK_a= 4.7.

A) 5.3
B) 4.1
C) 2.5
D) 0.4
E) None of the answers is correct.

Question 31

How is water able to be a solvent for so many biological molecules?

Question 32

If a particular reaction has a negative $\Delta$ G,is it likely to occur?

A) Not unless energy is added to the system
B) Yes, if it is coupled to another reaction
C) Yes, it is spontaneous.
D) No, it is not spontaneous.
E) Yes, as long as the temperature increases

Question 33

What is the net effect of many van der Waals interactions?

Question 34

Describe resonance structures.

Question 35

What two properties of water are important for biological interactions?

A) the polarity of water
B) the density of water
C) the cohesive properties of water
D) the polarity of water and the cohesive properties of water
E) the density of water and the cohesive properties of water

Question 36

What are the primary chemical components present in a phosphate buffer at pH 7.4?

A) H₃PO₄ and PO₄^3-
B) H₂PO₄^- and PO₄^3-
C) HPO₄^2- and PO₄^3-
D) H₂PO₄^- and HPO₄^2-
E) H₃PO₄ and HPO₄^2-

Question 37

What are some of the medical implications of the human genome project?

Question 38

What is significant about the fact that metabolic processes are common to many organisms?

Question 39

If most proteins are found surrounded by water in the cell,what type of functional groups would you expect to find on the surface of a water-soluble protein?

Question 40

What happens to nonpolar molecules in water?

A) They dissolve independently.
B) They aggregate together.
C) They precipitate.
D) All of the answers are correct.
E) None of the answers is correct.

Question 41

Provide a simple example of a process in which the entropy of a system changes.

Question 42

What are the enthalpy and entropy changes that accompany the formation of DNA double helices from complementary single strands of DNA?

Question 43

How do hydrophobic interactions aid in protein folding?

Question 44

If the First Law of Thermodynamics is true,how can biological processes be carried out?

Question 45

How are electrostatic forces used in protein folding?

Question 46

Describe the shape of methane.

Question 47

When solutions containing complementary single strands of DNA are mixed,a loss of entropy occurs.How is it that the Second Law of Thermodynamics is not violated?

Question 48

What thermodynamic and free-energy changes participate in protein folding?

Question 49

What is the significance of using $\Delta$ G in biochemistry?

Question 50

How can a cell exist if the Second Law of Thermodynamics is true?