Deck 2: The Molecules of Life

Question 1

Which is true of carbohydrates?

A)They may be part of the structure of bacteria.
B)They may serve as a source of food.
C)They contain carbon,hydrogen,and oxygen in a 1:2:1 ratio.
D)They may be bonded to proteins to form glycoproteins.
E)All of the choices are correct.

Answer 1

All of the choices are correct.

Question 2

Carbohydrates

A)form only ring structures.
B)form only linear structures.
C)may interconvert between ring and linear structures.
D)contain both ring and linear portions within the same molecule.

Answer 2

may interconvert between ring and linear structures.

Question 3

Sharing of electrons between 2 atoms forms a(n)

A)hydrogen bond.
B)ionic bond.
C)covalent bond.
D)strong bond.
E)covalent bond AND strong bond.

Answer 3

covalent bond AND strong bond.

Question 4

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

A)contribute a positive charge to the amino acid at pH 10.
B)contribute a negative charge to the amino acid at pH 10.
C)have no effect on the charge of the amino acid at pH 10.
D)are considered acidic amino acids.
E)contribute a negative charge to the amino acid at pH 10 AND are considered acidic amino acids.

Question 5

The N terminal in a protein

A)is the end characterized by a free carboxyl group.
B)is the end characterized by a free amino group.
C)is typically found in the middle of a protein.
D)refers to that area of a protein that is bound to another protein.

Question 6

Electrons

A)are found in areas outside the nucleus known as orbitals.
B)may gain or lose energy.
C)may move from one orbital to another.
D)are located farthest from the nucleus and have the least energy.
E)are found in areas outside the nucleus known as orbitals,may gain or lose energy,and may move from one orbital to another.

Question 7

Water

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

Question 8

The part of the atom that is most involved in chemical reactivity is the

A)proton.
B)neutron.
C)electron.
D)nucleus.

Question 9

The most important feature of a protein is its

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

Question 10

The subunits (building blocks)of proteins are

A)nucleotides.
B)phospholipids.
C)amino acids.
D)carbohydrates.

Question 11

If electrons are gained or lost in the formation of a bond,the bond is termed

A)covalent.
B)hydrogen.
C)ionic.
D)nonpolar.

Question 12

The negatively charged component of the atom is the

A)proton.
B)nucleus.
C)neutron.
D)electron.

Question 13

Acidic or basic amino acids are

A)readily soluble in water.
B)readily soluble in lipids.
C)able to form ions.
D)considered hydrophilic.
E)readily soluble in water,able to form ions,AND considered hydrophilic.

Question 14

D-amino acids are associated with

A)radioactive isotopes.
B)human proteins.
C)plant proteins.
D)bacterial cell walls.

Question 15

pH

A)is a measure of the hydrogen ion concentration.
B)utilizes a scale from 5 to 8.
C)is a linear (not logarithmic)scale.
D)is an abbreviation for "power of helium."
E)is a measure of the hydrogen ion concentration,utilizes a scale from 5 to 8,AND is a linear (not logarithmic)scale.

Question 16

Amino acids that contain many methyl (-CH3)groups

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

Question 17

The helices and sheets of amino acids form a protein's

A)primary structure.
B)secondary structure.
C)tertiary structure.
D)quaternary structure.

Question 18

In addition to investigations with bacteria that led to him being considered the Father of Microbiology,Pasteur also

A)found that some molecules can exist as stereoisomers.
B)created aspartame.
C)separated organic acids using a microscope.
D)discovered polarized light.
E)found that some molecules can exist as stereoisomers AND separated organic acids using a microscope.

Question 19

Protein denaturation can

A)occur due to certain chemicals.
B)occur due to pH changes.
C)occur due to high temperature.
D)cause the protein to no longer function.
E)All of the choices are correct.

Question 20

Charged atoms are termed

A)ions.
B)neutrons.
C)molecules.
D)polymers.

Question 21

If electrons are shared unequally,this forms a(n)

A)weak bond.
B)non-polar bond.
C)polar bond.
D)ionic bond.

Question 22

Structural isomers

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

Question 23

Which shows the incorrect complementary base pairing?

A)A:T
B)G:C
C)G:T
D)A:U
E)A:T,G:C,AND A:U

Question 24

If you placed the molecule in a vertical orientation,then from top to bottom,the two parallel strands of DNA are both oriented in the same,5' to 3',direction.

Question 25

The uncharged component of the atom is the

A)electron.
B)proton.
C)neutron.
D)muon.

Question 26

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

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)No generalizations can be made since melting temperature is strongly influenced by other factors.

Question 27

The components of fats are fatty acids and

A)amino acids.
B)nucleotides.
C)phosphate.
D)glycerol.
E)All of the choices are correct.

Question 28

Which of these bonds are weak individually but are much stronger as a group?

A)Covalent
B)Ionic
C)Neutron
D)Hydrogen
E)Ionic AND Hydrogen

Question 29

Which of the following is found in RNA but not in DNA?

A)Adenine
B)Ribose
C)Thymine
D)Uracil
E)Ribose AND Uracil

Question 30

Lipids,like nucleic acids and proteins,are made of strings of similar subunits.

Question 31

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

Question 32

The atomic weight is equal to

A)the number of electrons.
B)the number of electrons plus neutrons.
C)the number of protons.
D)the number of neutrons and protons.

Question 33

What type of bonding holds one strand of DNA to the complementary strand of DNA?

A)Covalent
B)Hydrogen
C)Disulfide
D)Ionic

Question 34

The atom,as a whole,is uncharged because

A)the number of protons equals the number of neutrons.
B)the number of electrons equals the number of neutrons.
C)neutrons neutralize the charges.
D)the number of protons equals the number of electrons.

Question 35

Which determines the chemical and physical properties of an atom of an element?

A)Electron
B)Neutron
C)Atomic weight
D)Atomic number

Question 36

Atoms that gain electrons are now

A)positively charged.
B)negatively charged.
C)neutral.
D)lighter.

Question 37

Steroids are simple lipids.

Question 38

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

Question 39

The positively charged component of the atom is the

A)electron.
B)neutron.
C)proton.
D)quark.

Question 40

The sugars found in nucleic acids consist of

A)3 carbon atoms.
B)5 carbon atoms.
C)7 carbon atoms.
D)9 carbon atoms.

Question 41

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

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.

Question 42

Proteins

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

Question 43

A protein

A)assumes any number of equally functional shapes.
B)may need help,in the form of chaperones,to assume the correct shape.
C)consists of a string of hydroxyl acids.
D)is always polar.
E)assumes any number of equally functional shapes AND may need help,in the form of chaperones,to assume the correct shape.

Question 44

The most important molecule(s)in the world is(are)

A)water.
B)protein.
C)carbohydrates.
D)nucleic acids.

Question 45

Side chains are important to proteins because they

A)help determine protein shape.
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 46

The characteristic common to all lipids is their

A)solubility in organic solvents.
B)hydrophilic nature.
C)large size.
D)hydrophobic nature.
E)solubility in organic solvents AND hydrophobic nature.

Question 47

The purines of DNA are

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

Question 48

Which is true of nucleotides?

A)They are the building blocks of DNA.
B)They carry chemical energy in their bonds.
C)They are part of certain enzymes.
D)They serve as specific signaling molecules.
E)All of the choices are true.

Question 49

Which is (are)true of lipids?

A)They are a major structural element of all cell membranes.
B)They act as gatekeepers of the cell.
C)They demark the inside vs.the outside of the cell.
D)They are a heterogeneous group of molecules.
E)All of the choices are correct.

Question 50

L-amino acids occur in proteins and are designated

A)unnatural.
B)natural.
C)rare.
D)left handed.
E)natural AND left handed.

Question 51

Dehydration reactions are involved in

A)the formation of polypeptides.
B)the formation of polysaccharides.
C)the formation of monosaccharides.
D)the formation of nucleotides.
E)the formation of polypeptides AND the formation of polysaccharides.

Question 52

The end of the nucleic acid chain that grows by adding more nucleotides is always the

A)5 prime end.
B)C terminal.
C)N terminal.
D)3 prime end.

Question 53

The -OH group in a carbohydrate

A)may be found above or below the plane of the ring.
B)is involved in the formation of stereoisomers.
C)is involved when linking monosaccharides together.
D)All of the choices are true.

Question 54

The carbohydrate(s)found in nucleic acids is/are

A)ribose.
B)glucose.
C)galactose.
D)deoxyribose.
E)ribose AND deoxyribose.

Question 55

The primary structure in a protein

A)refers to the helical folding of a protein.
B)refers to two or more polypeptides linked to one another.
C)refers to the sequence of amino acids.
D)refers to the initial folding of a protein.

Question 56

The energy storage form of ATP

A)contains deoxyribose.
B)contains ribose.
C)contains a pyrimidine base.
D)readily releases energy by breaking the bond between the base and the sugar.
E)contains deoxyribose,contains a pyrimidine base,AND readily releases energy by breaking the bond between the base and the sugar.

Question 57

As DNA is always double-stranded,RNA is always single-stranded.

Question 58

If the side chains of amino acids contain the ammonium ion,they readily form ions that

A)are described as acidic amino acids.
B)give positive electric charges to the amino acid.
C)are described as basic amino acids.
D)react with lipids to form lipoproteins.
E)give positive electric charges to the amino acid AND are described as basic amino acids.

Question 59

Weak bonds are important for the ______________ structure of proteins.

A)primary
B)secondary
C)tertiary
D)quarternary
E)secondary,tertiary,AND quarternary

Question 60

How many different amino acids are there to choose from when assembling a protein?

A)5
B)10
C)20
D)25

Question 61

Phospholipids are non-polar molecules.

Question 62

Microorganisms use hydrogen bonds to attach themselves to the surfaces that they live upon.Many of them lose hold of the surface because of the weak nature of these bonds and end up dying or being washed away.Why don't microbes just use covalent bonds instead?

A)Covalent bonds are always permanent bonds; the microbes could never get OFF their surface if they used them.
B)Covalent bonds depend on completely giving up or completely accepting an electron to form the bond.This isn't possible for many microbes without dramatically altering their basic molecular composition.
C)Covalent bonds typically require enzymes to form/break,whereas hydrogen bonds don't.If covalent bonds were used,it would require much more energy and molecules to be contributed from the cell.Hydrogen bonds don't have these requirements.
D)Covalent bonds may have more specific and stringent requirements for what atoms can bond with.This makes for stronger bonds,but also decreases the overall potential for bonds that could readily be created between the microbe and its desired surface.
E)C and D

Question 63

Unsaturated fats have lower melting points than saturated fats.

Question 64

Lipids are polar,hydrophilic molecules.

Question 65

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

Question 66

A biologist determined the amounts of several amino acids in two separate samples of pure protein.His data stated that Protein A possessed: 7% leucine,12% alanine,4% histidine,2% cysteine,and 5% glycine.Interestingly,Protein B had the same percentages of each 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:

A)He is correct; they have the same percentages of each amino acid,so they are identical protein molecules.
B)He is incorrect; while they may possess the same percentages of each amino acid,his findings say nothing about the order in which the amino acids are put together.The order will dictate the overall structure of the protein,so the two could be very different in shape,even though the amino acid totals are the same.
C)He is correct; 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.