Deck 2: The Chemistry and Energy of Life

Question 1

There are _______ natural elements in the universe.

A) 12
B) 24
C) 66
D) 94
E) 116

Answer 1

D

Question 2

Which element requires two additional electrons to fill the outermost electron shell?

A) Phosphorus
B) Carbon
C) Nitrogen
D) Oxygen
E) Hydrogen

Answer 2

D

Question 3

Which element has the same number of outer-shell (valence)electrons as oxygen?

A) Calcium
B) Nitrogen
C) Fluorine
D) Sodium
E) Sulfur

Answer 3

E

Question 4

Because atoms can have the same number of protons but a different number of neutrons,elements have

A) isotopes.
B) an integer atomic mass value.
C) more than one atomic number.
D) various means of forming chemical bonds.
E) isomers.

Question 5

All of the following molecules are examples of the octet rule except

A) CO₂.
B) H₂O.
C) H₂.
D) C₂H_6.
E) CH₃.

Question 6

You are given two identical vials of what you are told are identical molecules.However,one vial weighs more than the other,albeit on a very minute scale.One sample weighs more per molecule because the component elements have

A) different isotopes.
B) an integer atomic mass value.
C) more than one atomic number.
D) various means of forming chemical bonds.
E) different isomers.

Question 7

The part of the atom that determines how the atom behaves chemically is the

A) proton.
B) electron.
C) neutron.
D) innermost shell.
E) nucleus.

Question 8

How many hydrogen atoms would bind with one nitrogen atom to create a neutrally charged molecule?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 9

The mass number of an atom is the total number of _______ in its nucleus.

A) electrons
B) protons
C) protons and electrons
D) protons and neutrons
E) charges

Question 10

The number of protons in a neutral atom equals the number of

A) isotopes.
B) neutrons.
C) electrons plus neutrons.
D) neutrons minus electrons.
E) electrons.

Question 11

Which element is not found in all living systems?

A) Nitrogen
B) Phosphorus
C) Sulfur
D) Carbon
E) Helium

Question 12

Which element does not follow the octet rule?

A) Sodium
B) Chlorine
C) Carbon
D) Hydrogen
E) Nitrogen

Question 13

Phosphorus has an atomic number of 15 and an atomic mass of 31.How many neutrons does it have?

A) 5
B) 16
C) 30
D) 31
E) 47

Question 14

Which components of an atom do not add significantly to its mass?

A) Proton
B) Neutron
C) Electron
D) Nucleus
E) Both a and b

Question 15

You are given a project to devise structural formulas of molecules that will create stable compounds.The most important piece of information about the atoms you will need to consider is

A) their atomic weight.
B) the number and distribution of electrons.
C) their ability to form isomers.
D) the configuration of their nuclei.
E) their pH.

Question 16

An atom with _______ has an atomic mass of 14.

A) 14 neutrons
B) 14 electrons
C) 7 neutrons and 7 protons
D) 7 protons and 7 electrons
E) 6 electrons and 8 neutrons

Question 17

The atomic number of an element is the same as the number of _______ in each atom.

A) neutrons
B) protons plus electrons
C) protons
D) neutrons plus protons
E) neutrons plus electrons

Question 18

The element magnesium (Mg)has an atomic number of 12.Therefore,it has _______ electron shells and _______ electrons in the outermost shell.

A) 2;6
B) 2;10
C) 3;2
D) 3;4
E) 4;6

Question 19

Nitrogen-14 and nitrogen-15 are isotopes,and nitrogen-15 is used to determine protein structure.Based on this information,one can conclude that nitrogen-15 has _______ nitrogen-14.

A) more protons than
B) more neutrons than
C) more electrons than
D) an electronic configuration that is different from that of
E) the same number of protons and neutrons as

Question 20

The element silicon (Si)has an atomic number of 14.Therefore,its properties are similar to those of

A) sulfur.
B) oxygen.
C) phosphorus.
D) carbon.
E) boron.

Question 21

Cholesterol,which is composed primarily of carbon and hydrogen atoms,is therefore

A) insoluble in water.
B) a polar molecule.
C) a base.
D) an acid.
E) a buffer.

Question 22

A covalent bond is the sharing of _______ between atoms,whereas an ionic bond is the _______.

A) neutrons;sharing of electrons
B) electrons;electrical attraction between two atoms
C) protons;electrical attraction between two atoms
D) protons;sharing of electrons
E) electrons;transfer of electrons from one atom to another

Question 23

In addition to covalent bonds,which interactions are important in biological systems?

A) van der Waals interactions
B) Hydrogen bonds
C) Hydrophobic interactions
D) Ionic attractions
E) All of the above

Question 24

Two carbon atoms held together in a double covalent bond share _______ electron(s).

A) one
B) two
C) four
D) six
E) eight

Question 25

Ice is used to cool beverages primarily because

A) it is composed only of water.
B) it floats.
C) it dilutes the taste.
D) people like to chew it.
E) it absorbs a lot of heat when it melts because of hydrogen bonding.

Question 26

Which statement regarding the functional groups of carbon-based molecules is false?

A) They determine how the molecule interacts with other molecules in the environment.
B) They repel each other.
C) They determine the shape of the molecule.
D) They determine the specific properties of the molecule.
E) They may have interactions with specific functional groups on the same molecule.

Question 27

What determines if a molecule is polar,nonpolar,or ionic?

A) The number of protons
B) The bond distances
C) The differences in the electronegativities of the atoms
D) The ionic charges
E) The distance of the electrons from the nucleus

Question 28

The hydrogen bond between two water molecules forms because water is

A) polar.
B) nonpolar.
C) a liquid.
D) a small molecule.
E) hydrophobic.

Question 29

Which statement about the difference between ionic bonds and covalent bonds is true?

A) An ionic bond is stronger than a covalent bond.
B) A covalent bond occurs only in nonpolar molecules.
C) An ionic bond occurs more often in aqueous solutions.
D) An ionic bond occurs only in liquid methane.
E) Electron sharing is more equal in the covalent bond.

Question 30

All of these molecules are considered to be nonpolar except for

A) O₂.
B) N₂.
C) CH₄.
D) NaCl.
E) H₂.

Question 31

If you place a paper towel in a dish of water,the water will move up the towel by capillary action because water

A) molecules ionize.
B) is a good solvent.
C) molecules have hydrophobic interactions.
D) can form hydrogen bonds with the surface of the paper towel.
E) takes up large amounts of heat when it vaporizes.

Question 32

Magnesium (Mg)has an atomic number of 12.When it bonds with another element,it will likely

A) gain two electrons from the other element.
B) share four electrons with the other element.
C) lose two electrons to the other element.
D) form a hydrogen bond.
E) gain six electrons from the other element.

Question 33

Chemical bonds formed by electrical attractions are

A) covalent bonds.
B) ionic bonds.
C) hydrogen bonds.
D) van der Waals forces.
E) Both b and c

Question 34

Which statement about hydrogen bonds is true?

A) They form between two hydrogen atoms.
B) They form only between hydrogen and oxygen atoms within a molecule.
C) They form between a highly electronegative atom and hydrogen.
D) They involve a transfer of electrons.
E) They are the strongest bonds because of their length.

Question 35

Chlorine (Cl)has an atomic number of 17.When it bonds with another element,it will likely

A) gain one electron from the other element.
B) share four electrons with the other element.
C) lose one electron to the other element.
D) form a double bond.
E) gain three electrons from the other element.

Question 36

The two atoms in a hydrogen molecule are held together by

A) hydrogen bonds.
B) ionic attractions.
C) van der Waals forces.
D) a shared pair of electrons.
E) gravity.

Question 37

Sweating is a useful cooling device for humans because water

A) has a high heat of vaporization.
B) has little cohesion strength.
C) has little hydrogen bonding.
D) is an outstanding solvent.
E) ionizes readily.

Question 38

A single covalent chemical bond represents the sharing of how many electrons?

A) One
B) Two
C) Three
D) Four
E) Six

Question 39

A compound with the molecular formula C₂H₄ has _______ double bond(s).

A) one C-H
B) two C-H
C) four C-H
D) one C-C
E) no

Question 40

Phosphorus has an atomic number of 15,and on average phosphorus atoms have a total of 30.974 protons and neutrons.From this information one can conclude that this element

A) has isotopes.
B) forms isomers.
C) dissolves in liquid methane.
D) is an ion.
E) is radioactive.

Question 41

Maltose,which is composed of two glucose units,can be classified as a

A) disaccharide.
B) hexose.
C) pentose.
D) polysaccharide.
E) monosaccharide.

Question 42

A type of molecule very often drawn with a single six-sided ring structure is

A) sucrose.
B) an amino acid.
C) a steroid.
D) a fatty acid.
E) glucose.

Question 43

Starch and glycogen,which are both polysaccharides,differ in their functions in that starch is _______,whereas glycogen _______.

A) the main component for plant structural support;is an energy source for animals
B) a structural material found in plants and animals;forms external skeletons in animals
C) a temporary compound used to store glucose;is a highly stable compound that stores complex lipids
D) the principal energy storage compound of plants;is the main energy storage of animals
E) the main energy storage of animals;is a temporary compound used to store glucose

Question 44

When exposed to extreme heat,the human body relies on _______ to absorb excess heat and maintain normal body temperature.

A) evaporation
B) condensation
C) respiration
D) transpiration
E) convection

Question 45

The general chemical formula for carbohydrates includes the atoms

A) C,H,and N.
B) C and H.
C) C,H,and P.
D) C,H,and O.
E) C,H,O,and N.

Question 46

Aldehydes and ketones are very similar in that they both contain

A) phosphorus atoms.
B) sulfur atoms.
C) a C=O group.
D) nitrogen atoms.
E) two "R" groups.

Question 47

Molecules containing a large number of hydroxyl groups are

A) basic.
B) structurally less stable than those with fewer hydroxyls.
C) complex macromolecules.
D) nonpolar.
E) soluble in water.

Question 48

Seeds contain dense aggregates of starch.What role does water play in how the seeds use the stored starch?

A) Water is needed to break the hydrogen bonds in the starch aggregates,allowing ready access to stored energy.
B) Water is needed to break the peptide bonds in the starch polymers,releasing more water for the plant's use.
C) Water is needed to activate enzymes that will dissolve the starch into its disaccharide monomers that are used for growth.
D) Water is needed to dissolve the starch so that it can mix with fats and create new energy compounds utilized by the growing plant.
E) Water is needed to help transport starch across membranes,allowing communication between the newly growing plant cells.

Question 49

In condensation reactions,the atoms that make up a water molecule are derived from

A) oxygen.
B) only one of the reactants.
C) both of the reactants.
D) carbohydrates.
E) enzymes.

Question 50

A simple sugar with the formula C₅H₁₀O₅ can be classified as a

A) hexose.
B) polysaccharide.
C) disaccharide.
D) pentose.
E) lipid.

Question 51

Which statement about the hydrolysis of the disaccharide maltose to two glucose units is true?

A) The reaction is energy neutral.
B) The potential energy contained within glucose is larger than that of maltose.
C) The hydrolysis reaction involves the breaking of a single covalent bond.
D) The hydrolysis reaction involves the breaking of two covalent bonds.
E) At completion,the concentration of maltose is higher than the concentration of glucose.

Question 52

Starch and glycogen,which are both polysaccharides,differ structurally in that glycogen _______,whereas starch _______.

A) is highly branched;is moderately branched
B) consists of parallel strands;is highly branched
C) consists of a combination of branching and parallel strands;is moderately branched
D) is moderately branched;consists of parallel strands
E) is highly branched;consists of parallel strands

Question 53

The main function of cellulose,the most abundant organic compound on Earth,is

A) as a storage compound for genetic information.
B) as a storage compound for energy in plant cells.
C) as a storage compound for energy in animal cells.
D) as a component of biological membranes.
E) as an excellent structural material that can withstand harsh environmental conditions without substantial change.

Question 54

During the formation of a polymer from monomers,a(n)_______ is formed.

A) molecule of water
B) disulfide bridge
C) hydrophobic bond
D) hydrophilic bond
E) ionic bond

Question 55

Sucrose,known as common table sugar,is a

A) hexose.
B) lipid.
C) simple sugar.
D) glucose.
E) disaccharide.

Question 56

A molecule with the formula C₁₆H₃₀O₁₅ is a

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

Question 57

The amino and carboxyl functional groups tend to form bases and acids by attracting or releasing

A) a neutron.
B) a proton.
C) an electron.
D) a proton and an electron.
E) a neutron and a proton.

Question 58

The monomers that make up polymeric carbohydrates like starch are called

A) nucleotides.
B) trisaccharides.
C) monosaccharides.
D) nucleosides.
E) fatty acids.

Question 59

Which statement about condensation reactions is false?

A) They are used in protein synthesis.
B) They are used in polysaccharide synthesis.
C) They involve covalent bonds.
D) They consume water as a reactant.
E) Different condensation reactions produce different kinds of macromolecules.

Question 60

Starch and glycogen are different in that only one of them

A) is a polymer of glucose.
B) contains ribose.
C) is made in plants.
D) is an energy storage molecule.
E) can be digested by humans.

Question 61

Cholesterol is soluble in ether,an organic solvent,but it is not soluble in water.Based on this information,to which class of biological molecules does cholesterol belong?

A) Nucleic acids
B) Carbohydrates
C) Proteins
D) Lipids
E) Sugars

Question 62

Why does a starchy food,like bread,become hard and stale when it dries out?

A) Cellulose molecules aggregate in the absence of water.
B) In the absence of water,starch forms hydrogen bonds between polysaccharides,which then aggregate.
C) The release of carbon dioxide causes the bread to harden.
D) Water and heat cause the polysaccharide chains to bind together.
E) Mold growth interferes with glycosidic linkages,causing the bread to harden.

Question 63

You are given two fat-like solid substances and upon analysis you determine that Sample A has a higher melting point than sample B.You thus come to the conclusion that sample A

A) has a higher number of carbon-carbon double bonds than sample B.
B) has a lower number of carbon-carbon double bonds than sample B.
C) is a saturated fat and sample B is an unsaturated fat.
D) is an unsaturated fat and sample B is a saturated fat.
E) is a triglyceride and sample B is a simple lipid.

Question 64

Triglycerides are _______;phospholipids are _______.

A) hydrophobic;amphipathic
B) hydrophobic;hydrophilic
C) amphipathic;hydrophobic
D) hydrophilic;amphipathic
E) hydrophilic;hydrophobic

Question 65

The arrangement of glycosidic linkages in _______ makes it a much more stable molecule than _______.

A) guanine;cytosine
B) RNA;DNA
C) sucrose;lactose
D) cellulose;starch
E) testosterone;cortisone

Question 66

The portion of a phospholipid that contains the phosphorous group has one or more electric charges,which make this region of the molecule

A) hydrophobic.
B) hydrophilic.
C) nonpolar.
D) unsaturated.
E) saturated.

Question 67

Lipids form the barriers surrounding various compartments within an organism.Which property of lipids makes them a good barrier?

A) Many biologically important molecules and ions are not soluble in lipids.
B) Lipids are polymers.
C) Lipids store energy.
D) Lipids are triglycerides.
E) Lipids release large amounts of energy when broken down.

Question 68

In a biological membrane,the phospholipids are arranged with the fatty acid chains facing the interior of the membrane.As a result,the interior of the membrane is

A) hydrophobic.
B) hydrophilic.
C) charged.
D) polar.
E) filled with water.

Question 69

Molecules that are both attracted to water and repel water are called

A) hydrophilic.
B) hydrophobic.
C) amphipathic.
D) amphoric.
E) glycosidic.

Question 70

You have isolated an unidentified liquid from a sample of beans.You add the liquid to a beaker of water and shake vigorously.After a few minutes,the water and the other liquid separate into two layers.To which class of biological molecules does the unknown liquid most likely belong?

A) Carbohydrates
B) Lipids
C) Proteins
D) Enzymes
E) Nucleic acids

Question 71

You look at the label on a container of shortening and see the words "hydrogenated vegetable oil." This means that during processing,the number of carbon-carbon double bonds in the oil was decreased.What is the result of decreasing the number of double bonds?

A) The oil now has a lower melting point.
B) The oil is now solid at room temperature.
C) There are more "kinks" in the fatty acid chains.
D) The oil is now a derivative carbohydrate.
E) The fatty acid is now a triglyceride.

Question 72

Which statement about the exergonic hydrolysis of maltose to glucose is true?

A) The reaction requires the input of free energy.
B) The free energy of glucose is larger than the free energy of maltose.
C) The reaction is not spontaneous.
D) The reaction releases free energy.
E) At equilibrium,the concentration of maltose is higher than the concentration of glucose.

Question 73

Fatty acids are molecules that

A) contain fats bonded to a glycerol.
B) are composed of a hydrocarbon chain and a carboxyl group.
C) are carbohydrates linked to a hydrocarbon chain.
D) contain glycerol and a carboxyl group.
E) are always saturated.

Question 74

A fat contains fatty acids and

A) glycerol.
B) a base.
C) an amino acid.
D) a phosphate.
E) None of the above

Question 75

Oil and water do not mix easily because the fat molecules aggregate in water as a result of

A) van der Waals forces.
B) covalent bonds.
C) disulfide bonds.
D) hydrogen bonds.
E) glycosidic linkages.

Question 76

The sum total of all the chemical reactions in a living structure is called

A) energetics.
B) activity.
C) digestive power.
D) entropy.
E) metabolism.

Question 77

Lipids are

A) insoluble in water.
B) important for energy storage.
C) hydrophobic.
D) important constituents of biological membranes.
E) All of the above

Question 78

What can never be created or destroyed?

A) Entropy
B) Energy
C) Free energy only
D) Thermal energy only
E) Potential energy only

Question 79

Water held back by a dam represents what kind of energy?

A) Hydroelectric
B) Irrigation
C) Potential
D) Kinetic
E) Metabolic

Question 80

Phosphorylation of ADP to ATP is endergonic,whereas the hydrolysis of ATP to ADP is exergonic.Therefore,the two reactions can be

A) substrates.
B) endothermic.
C) kinetic.
D) activated.
E) linked.