Deck 1: Introduction to Biochemistry

Question 1

A spontaneous chemical reaction always has a ________ change.

A)positive Gibb's free energy
B)negative Gibb's free energy
C)positive enthalpy
D)negative enthalpy
E)positive entropy

Answer 1

negative Gibb's free energy

Question 2

Which statement is true about the Gibb's free energy of a reaction?

A)It is dependent on the concentrations of both products and reactants.
B)It is dependent only on the concentrations of the reactants.
C)It is dependent only on the concentrations of the products.
D)It is not dependent on the concentrations of either the products or reactants.

Answer 2

It is dependent on the concentrations of both products and reactants.

Question 3

If a reaction is at equilibrium,what is the free energy change?

A)It is always positive.
B)It is always negative.
C)It could be either positive or negative depending on the reaction.
D)It equals zero.

Answer 3

It equals zero.

Question 4

Prokaryotes are valuable tools for biochemists because

A)E.coli is well-studied and typical of prokaryotes.
B)they contain as many genes as eukaryotic cells.
C)many of their chromosomes are sequenced.
D)they are not very diverse organisms.
E)All of the above

Question 5

Most of the energy required for life on Earth is supplied by ________.

A)geothermal energy
B)the sun
C)cosmic radiation
D)the conversion of ADP to ATP
E)mechanical energy

Question 6

Which elements account for more than 97% of the weight of most organisms?

A)C,H,N,Mg,O,S
B)C,H,N,O,P,S
C)C,H,N
D)Fe,C,H,O,P
E)Ca²+,K+,Na+,Mg²+,Cl-

Question 7

Which statement about cellulose is false?

A)It is the most abundant polysaccharide in nature.
B)Its monomers are joined by glycosidic bonds.
C)It is present in the stems of flowering plants.
D)The hydroxyl groups of neighboring cellulose molecules interact to form strong,insoluble fibers.
E)It is a branched polymer of glucose.

Question 8

Which statement is true about a reaction with an equilibrium constant,Keq,equal to 1000?

A)The forward rate constant is 1000 times greater than the reverse rate constant.
B)The forward rate constant is 3 times greater than reverse rate constant.
C)The forward rate constant is 1000 times smaller than the reverse rate constant.
D)The forward rate constant is 3 times smaller than the reverse rate constant.
E)There is not enough information given to compare the forward and reverse rate constants.

Question 9

The study of the energy changes during metabolic reactions is called ________.

A)bioinformatics
B)metabodynamics
C)thermometrics
D)bioenergetics
E)biological heat dynamics

Question 10

A dipeptide forms when a functional ________ group of one amino acid reacts with the functional ________ group of another amino acid to form a ________ bond.

A)carboxylate,amino,double
B)carboxylate,amino,enzyme
C)amino,carboxylate,phosphate
D)amino,carboxylate,peptide

Question 11

Which functional group is shown?

A)Primary amine.
B)Acyl.
C)Amide.
D)Anhydride.
E)Nitrile.

Question 12

Proteins in biological membranes may be

A)porous.
B)attached to the membrane surface.
C)span the membrane.
D)all of the above.
E)B and C only.

Question 13

The lock-and-key theory described the action of

A)enzymes as keys that fit different chemicals.
B)substrates as keys that fit different enzymes.
C)enzymes as locks that fit other enzymes.
D)substrates as locks that fit different enzymes.

Question 14

According to Crick's Central Dogma of molecular Biology,there can be NO transfer of information from

A)DNA to RNA.
B)RNA to RNA.
C)RNA to protein.
D)protein to RNA.

Question 15

Which linkage(s)occur extensively in nucleotides?

A)Amide.
B)Phosphoanhydride.
C)Phosphate ester.
D)Ether.
E)Both B and C above.

Question 16

Wohler showed that a chemical found only in living organisms can be made from inorganic substances when he synthesized ________.

A)Ammonium cyanate
B)Amino acids
C)Urea
D)Uric acid

Question 17

When Keq of a reaction = 1,then

A)the forward reaction is faster than the reverse reaction.
B)the reverse reaction is faster than the forward reaction.
C)the forward and reverse reaction rate constants are equal.
D)more products are formed than reactants.
E)fewer products are formed than reactants.

Question 18

Sugars such as glucose are monomers of polysaccharides that are linked together when covalent bonds form between one ________ group of one sugar to the same group on another sugar.

A)ester
B)carboxyl
C)amino
D)hydroxyl

Question 19

What is the correct order in which these key breakthroughs in biochemistry occurred?
I. Watson and Crick DNA structure
II. Crick Central dogma
III. Avery,MacLeod and McCarty DNA work on Streptococcus
IV. Widespread use of computers

A)I,II,III,IV
B)III,I,II,IV
C)II,I,III,IV
D)IV,III,I,II

Question 20

Which statement is true?

A)If DG is negative,then the rate of the reaction will be fast.
B)If DG is positive,then the rate of the reaction will be fast.
C)If DG is negative,then the rate of the reaction will be slow.
D)If DG is positive,then the rate of the reaction will be slow.
E)The reaction rate is independent of DG.

Question 21

Which cellular component carries out oxidation reactions,some of which produce hydrogen peroxide?

A)Peroxisomes.
B)Mitochondria.
C)Chloroplasts.
D)Lysosomes.
E)Vacuoles.

Question 22

The absolute molecular mass of macromolecules is given in daltons,where 1 dalton = 1 atomic mass unit.

Question 23

Fermentation in the absence of cells demonstrated that metabolic processes were chemical in nature.

Question 24

Lysozyme is an enzyme with a cleft or depression at its active site.

Question 25

Biochemists describing the molecular weight of a protein really mean the atomic weight in grams.

Question 26

Why is it important that the enzymes in lysosomes are more active at acidic pH than at neutral pH?

A)Since lysosomes are primarily found in the stomach acid of mammals,their pH dependence allows for maximum efficiency for the digestion of foodstuffs.
B)It prevents their diffusion out of the lysosomes.
C)It maximizes the interaction with their substrates which are always bases.
D)It prevents them from accidentally degrading the macromolecules in the cytosol.
E)It allows for regulation of their uptake by the mitochondria.

Question 27

The modified lock-and-key theory of enzyme action proposed by Emil Fischer has been completely replaced by more modern ideas of catalysis.

Question 28

Bioinformatics has permitted rapid advances in our understanding of structural macromolecules from living cells.

Question 29

The role of DNA as the genetic material was confirmed by transforming Streptococci in experiments performed several years after the famous Watson and Crick description of DNA structure.

Question 30

The conformation of a protein enzyme determines whether it is functional or not.

Question 31

Functional groups describe one or more portions of organic compounds found in living cells.

Question 32

Enzymes are not as efficient as most catalysts used in organic chemistry,since they must function at body temperature.

Question 33

A phosphate ester contains a phosphate functional group.

Question 34

Enzymes are protein catalysts that form an intermediate with a substrate that fits into it.

Question 35

Mr is the mass of a molecule relative to 1/12 the mass of an atom of the most common isotope of carbon.

Question 36

A peptide bond is formed by the condensation of different functional groups from two amino acids.

Question 37

Molecules from living cells cannot be synthesized outside of living cells.

Question 38

Water is often a product when monomers join to form a macromolecule.

Question 39

Under most biological conditions,acid groups and amino groups are fully protonated.

Question 40

Crick referred to the flow of information from nucleic acid to protein as the Central Dogma.

Question 41

Thermodynamics and its laws are obeyed by living cells.

Question 42

Mitochondria are the main sites of energy transduction in aerobic eukaryotic cells.

Question 43

Sugars with six carbons are the only ones capable of forming a ring structure as shown in a Haworth projection.

Question 44

ATP contains both phosphoester and phosphoanhydride linkages.

Question 45

The endoplasmic reticulum is the major site of RNA synthesis and the site of assembly of ribosomes.

Question 46

Lipids aggregate to form bilayers because some lipid molecules are hydrophobic and other lipid molecules are hydrophilic.

Question 47

The tendency of a metabolic reaction to proceed is due to the free energy of both the reactants and products as well as the change in randomness of that reaction.

Question 48

A phosphodiester linkage in DNA contains two phosphorous atoms.

Question 49

Biochemical reactions are more likely to proceed if the reaction has an increase in enthalpy (△H)and a decrease in entropy

Question 50

Ribosomes on the surface of rough endoplasmic reticulum are the site of ATP synthesis.

Question 51

All prokaryotic cells are about 1/10 the size of an average eukaryotic cell or smaller.

Question 52

The Haworth projection of the ring form of a monosaccharide always shows a flat plane with one edge projecting out of the page (using thicker lines).

Question 53

Diffusion is an adequate means of distributing nutrients in prokaryotic cytoplasm because they have more surface area than volume compared to most eukaryotes.

Question 54

All cells have kept the same general patterns of metabolism,a very similar genetic code and the same monomers or residues.

Question 55

The nuclear envelope is a membrane that surrounds the nucleus and is continuous with the endoplasmic reticulum.

Question 56

Eukaryotes include plants,animals and bacteria.

Question 57

The Golgi apparatus consists of flattened,fluid-filled,membranous sacs and is responsible for chemical modification and sorting of some biomolecules.

Question 58

Eukaryotic cells are distinguished from prokaryotes by their usually larger size,a complex cytoskeleton and membrane-bounded organelles.

Question 59

Chloroplasts are organelles found in plants,algae and some protists and are the site of photosynthesis.

Question 60

The only reason phages are not considered to be cells is because they do not contain a plasma membrane.

Question 61

Actin has been shown to be one of the most evolutionarily conserved proteins.It is present in all eukaryotic cells and frequently is the most abundant protein in the cell.

Question 62

The chemical name for ATP is alanine triphosphate.

Question 63

In eukaryotic cells lysosomes are specialized digestive vesicles with a highly acidic interior.

Question 64

Absolute zero is equal to 0°C.

Question 65

The process of cell division that occurs in the tissues is called mitosis.

Question 66

One Angstrom is equal to 1 × 10-10 meters.

Question 67

The mitochondria and Golgi apparatus are two organelles which originated from bacteria and were incorporated into eukaryotic cells via symbiosis.

Question 68

The diffusion of large molecules such as enzymes is significantly slowed by the presence of the cytoskeleton.

Question 69

In an animal cell,DNA can be found only in the nucleus.

Question 70

The filament fibers in the cytoskeleton are composed primarily of carbohydrate molecules.

Question 71

The mitotic spindles are formed from microtubule proteins.

Question 72

Photosynthesis involves capturing energy from light that is then used to drive the formation of carbohydrates from carbon dioxide and water.