Deck 2: The Molecules of Cells

Question 1

The chemical reactivity of an element is dependent on

A) the number of protons.
B) the arrangement of neutrons.
C) the number of electrons in the outermost shell.
D) the number of protons and neutrons.
E) the number of electrons in the inner shell.

Answer 1

C
Explanation: It is the outermost shell of an atom that can potentially react with electrons in the outermost shells of other atoms. The protons and neutrons remain in the nucleus and do not engage in chemical reactions.

Question 2

Which of the following statements is NOT true of chemical bonds?

A) Both ionic and covalent bonds involve electrons in the outer shell.
B) Covalent bonds share electrons between two atoms.
C) An atom involved in an ionic bond has an unequal number of electrons and protons.
D) Salts are covalently bonded.
E) The atoms in a molecule of water (H₂O) are covalently bound together.

Answer 2

D
Explanation: Salts, such as sodium chloride (NaCl) are ionic compounds. All the other answer choices are accurate statements.

Question 3

A covalent bond is

A) a type of bond that results in ionic compounds.
B) the transfer of electrons from one atom to another.
C) a sharing of electrons between two atoms.
D) an attraction of charged atoms.
E) a sharing of protons between two atoms.

Answer 3

C
Explanation: A covalent bond results when two atoms share electrons in such a way that each atom has eight electrons in its outermost shell. In contrast, ionic compounds result from the complete transfer of electrons between bonded atoms.

Question 4

Which of the following statements about hydrogen bonding is incorrect?

A) Hydrogen bonding occurs only between water molecules.
B) Hydrogen bonds are easily broken.
C) Hydrogen bonding can occur between different molecules or within the same molecule.
D) Most hydrogen bonds involve hydrogen and oxygen or nitrogen.
E) The structure of a large, complex molecule can be influenced by hydrogen bonding.

Question 5

Calcium chloride,CaCl₂,is an ionic compound in which

A) one chlorine atom transferred an electron to the other chlorine atom.
B) each chlorine atom has lost electrons.
C) calcium has two extra electrons in its innermost shell.
D) calcium has gained two electrons.
E) calcium has lost two electrons.

Question 6

Polar covalent bonds result from

A) unequal sharing of electrons in a covalent bond.
B) equal sharing of electrons in a covalent bond.
C) equal sharing of electrons in an ionic bond.
D) unequal sharing of electrons in an ionic bond.
E) hydrogen bonding between molecules.

Question 7

Potassium,a metal with one electron in the outermost shell,will react with how many chlorine atoms? (Chlorine is a nonmetal with seven electrons in the outermost shell.)

A) 5
B) 7
C) 1
D) 2
E) 3

Question 8

If an element has an atomic number of 15,then

A) the atomic mass must also be 15.
B) the atom has 15 electrons.
C) there are 7 electrons in the outermost shell.
D) the atom has 15 neutrons.
E) the atom must have only one orbital.

Question 9

The difference between ¹²₆C and ¹⁴₆C is

A) the number of electrons.
B) the number of protons.
C) the number of neutrons.
D) the number of carbon atoms.
E) the number of ionic bonds.

Question 10

Which of the following is not a property of water that results from hydrogen bonding?

A) The temperature of water changes very slowly.
B) Many polar substances dissolve in water.
C) Water molecules have cohesiveness.
D) Ice melts at -100 ^$\circ$ C.
E) Water has a high surface tension.

Question 11

If neutral atoms become positive ions,they

A) gain electrons.
B) lose electrons.
C) gain protons.
D) lose protons.
E) do not change.

Question 12

If an element has an atomic number of 12,how many electrons are in its outermost shell?

A) 1
B) 10
C) 8
D) 2
E) 12

Question 13

An ion is an atom that

A) exists in a gaseous state.
B) has a net charge.
C) does not have a net charge.
D) shares electrons with other atoms.
E) shares neutrons with other atoms.

Question 14

The nucleus of an atom contains

A) neutrons and electrons.
B) electrons only.
C) protons, neutrons, and electrons.
D) protons and neutrons.
E) neutrons only.

Question 15

The isotope ¹⁴₆C has

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

Question 16

The atomic mass of an element

A) is determined by its protons and neutrons.
B) equals the number of protons plus the number of electrons.
C) equals the number of neutrons.
D) changes after each reaction.
E) depends on the number of electrons in the outermost shell.

Question 17

To measure the activity of the human brain during certain thought processes,a short-lived radioactive sugar is injected in the carotid artery and is utilized by those cells that are most active.This shows up on a PET scan and demonstrates the detection of

A) ionic bonds.
B) high levels of radiation.
C) covalent bonds.
D) neutrons.
E) isotopes.

Question 18

When an ionic bond forms,electrons are

A) lost from both atoms.
B) gained by both atoms.
C) shared equally by both atoms.
D) totally lost from the paired atoms.
E) transferred from one atom to another.

Question 19

Which of the following molecules is NOT a compound?

A) H₂O
B) HCl
C) H₂
D) C₆H₁₂O₆
E) NaOH

Question 20

Isotopes of a given element have

A) the same number of protons but differ in atomic mass.
B) the same atomic mass but different number of protons.
C) different number of electrons.
D) the same number of protons and atomic mass.
E) the same number of neutrons.

Question 21

The lower the pH

A) the lower the hydrogen ion (H⁺) concentration.
B) the more acidic the solution.
C) the higher the pH.
D) the greater the hydroxide ion (OH^-) concentration.
E) the closer the hydroxide ion (OH^-) concentration comes to equaling the hydrogen ion (H⁺) concentration.

Question 22

Which statement regarding acids and bases is correct?

A) Acids increase the pH, and bases decrease the pH.
B) Acids increase the proportion of hydrogen ions (H⁺), and bases reduce the proportion of H⁺.
C) Acids are harmful, but bases are not harmful.
D) Acids combine with bases to form buffers.
E) Acids combine with bases to form sugars.

Question 23

Hydrogen bonding produces which following property of water?

A) Boiling at a lower temperature than expected.
B) Water is less dense as ice than as liquid water.
C) Water absorbs heat with a large change in temperature.
D) Water releases heat with a large change in temperature.
E) Water can be more dense as ice than as liquid water.

Question 24

A genetic mutation can cause a change in the sequence of the 20 amino acids used to build proteins.Such a change is a change to the protein's

A) primary structure only.
B) secondary structure only.
C) tertiary structure only.
D) primary structure, but this will likely alter higher levels of structure as well.
E) quaternary structure only.

Question 25

Rain falling in the northeastern U.S.has a pH between 5.0 and 4.0.Normally,rainwater has a pH of about 5.6.Which of the following statements is not correct?

A) The pH of the rainwater has changed from neutral to acidic.
B) The pH of the rainwater has become more acidic.
C) The hydrogen ion (H⁺) content of the rainwater has increased.
D) The proportion of hydroxide ions (OH^-) in the rainwater has declined.
E) The rainwater with a pH of 4.0 is ten times more acidic than the rainwater with a pH of 5.0.

Question 26

One carbon atom can form covalent bonds with up to ___ other atoms to form an organic molecule.

A) 2
B) 3
C) 4
D) 6
E) 8

Question 27

The moon lacks life and varies dramatically in temperature.If we could keep a layer of water spread on the surface of the moon,what effect would it have?

A) Life would be possible but it would have to withstand these extremes in temperature.
B) Water would absorb and hold heat and moderate the temperature extremes.
C) The temperatures would drop to the lower extremes.
D) Because water has a high heat of vaporization, the temperatures would rise to the upper extremes.
E) Physical conditions would remain the same.

Question 28

Which of the following molecules is inorganic?

A) CH₄
B) CO₂
C) C₆H₁₂O₆
D) C₁₂H₂₂O₁₂
E) C₆H₆

Question 29

Organic molecules

A) always contain carbon.
B) always contain hydrogen.
C) always contain carbon and hydrogen.
D) are found only in organisms, hence their name.
E) are always food molecules.

Question 30

In water,a weak hydrogen bond occurs between hydrogen in one molecule and

A) an oxygen atom in the same molecule.
B) an oxygen atom in a different molecule.
C) a hydrogen atom in the same molecule.
D) a hydrogen atom in a different molecule.
E) either hydrogen and oxygen atoms of different molecules.

Question 31

Since pure water is neutral,it contains

A) no hydrogen ions (H⁺).
B) no hydroxide ions (OH^-).
C) neither hydrogen ions (H⁺) nor hydroxide ions (OH^-).
D) an equal number of hydrogen ions (H⁺) and hydroxide ions (OH^-).
E) seven times more hydrogen ions (H⁺) than hydroxide ions (OH^-).

Question 32

Water is a liquid at room temperature.This is due to

A) ionic bonding of the atoms in the water molecule.
B) covalent bonding in the water molecule.
C) covalent bonding between water molecules.
D) hydrogen bonding within the water molecule.
E) hydrogen bonding between water molecules.

Question 33

The water strider is an insect that skates across the water without sinking.The tips of its feet must be coated with molecules that are

A) ions.
B) hydrophilic.
C) hydrophobic.
D) basic.
E) acidic.

Question 34

Two molecules of glucose combine to form a disaccharide molecule during a(n)________ reaction.

A) dehydration
B) hydrolysis
C) hydrogen bond
D) ionic bond
E) inert

Question 35

DNA codes for the sequence of amino acids in the primary structure of a protein,but not for sugars or lipids.This is because

A) only proteins are involved in living metabolic reactions.
B) sugars and lipids code for their own replication.
C) sugars and lipids are ever present in the living environment and are not used in living structures.
D) other hereditary molecules code for sugars and lipids.
E) proteins are the main structural and functional components of cells.

Question 36

The pH of blood is slightly basic.Which of the following would therefore be an expected pH for blood?

A) 6.4
B) 4.6
C) 4.7
D) 7.4
E) 13.8

Question 37

Aspirin is acetyl salicylic acid and can therefore pose a problem to people who have ulcers.Bufferin uses a buffer to neutralize this effect by

A) substituting another ingredient for the acetyl salicylic acid.
B) adding a drug to stimulate the immune system.
C) adding salts to neutralize the acid.
D) adding an equal amount of hydroxide (OH^-) ions.
E) adding chemicals that take up excess hydrogen (H⁺) ions.

Question 38

You notice that rain water forms "beads" on your car.This is an example of what property of water?

A) cohesion
B) dissociation
C) high heat of vaporization
D) adhesion
E) solvent

Question 39

Potassium hydroxide (KOH)almost completely dissociates in aqueous solution into K⁺ and OH^- and is therefore a

A) strong acid.
B) strong base.
C) weak base.
D) weak acid.
E) nonpolar covalent molecule.

Question 40

Buffers

A) are strong acids or bases.
B) keep the pH within normal limits.
C) release large amounts of hydrogen ions (H⁺).
D) lower the pH.
E) increase the pH.

Question 41

In the search to discover the agents that cause mad cow disease,scrapie in sheep,and CJD and kuru in humans,diseased brain tissues were passed through a fine filter to remove bacteria.The filtrate was still infectious,indicating that something smaller than bacteria,either viruses or organic molecules,must be the causative agent.If a virus were responsible for these brain diseases,then the infectious agent would contain either RNA or DNA.Other possibilities were that the agent was a carbohydrate,fat,or protein.Tissue filtrates were treated with agents that destroyed just one of these chemicals and then injected into a healthy animal,with the results as follows.What is the infectious agent?
$\bullet$ Amylase digests carbohydrates; tissue filtrate still infects healthy test animal.
$\bullet$ Lipase digests fats; tissue filtrate still infects healthy test animal.
$\bullet$ Formaldehyde and/or heat denatures DNA and RNA; tissue filtrate still infects healthy test animal.
$\bullet$ Trypsin digests protein; tissue filtrate does not infect healthy test animal.

A) carbohydrate
B) fat
C) protein
D) DNA or RNA
E) Could be carbohydrate, fat, or DNA or RNA but not protein.

Question 42

Maltose is classified as a

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

Question 43

Hemoglobin is a protein composed of two pairs of polypeptide chains.What is the highest level of protein structure represented in hemoglobin?

A) primary
B) secondary
C) tertiary
D) quaternary
E) molecular

Question 44

The structure shown in Figure 2.24 is

A) a glucose molecule.
B) a fatty acid molecule.
C) a glycerol molecule.
D) a protein molecule.
E) an amino acid.

Question 45

Nucleic acids are polymers of

A) amino acids.
B) nucleotides.
C) glycerol.
D) monosaccharides.
E) fatty acids.

Question 46

A long chain of carbon atoms with hydrogen atoms attached,ending in the acidic group -COOH would be a(n)

A) triglyceride.
B) amino acid.
C) fatty acid.
D) nucleic acid.
E) monosaccharide.

Question 47

Enzymes are organic compounds classified as

A) nucleic acids.
B) carbohydrates.
C) lipids.
D) steroids.
E) proteins.

Question 48

Which of these combinations would be found in a nucleotide?

A) base-acid-salt
B) adenine-thymine-uracil
C) base-sugar-phosphate
D) DNA-RNA-nucleus
E) sugar-protein-fat

Question 49

The _____ structure of a protein consists of the sequence of the amino acids joined together by peptide bonds.

A) primary
B) secondary
C) tertiary
D) quaternary
E) molecular

Question 50

Hydrolysis of a fat results in the formation of

A) glycerol only.
B) fatty acids only.
C) glucose only.
D) two monosaccharides.
E) both glycerol and fatty acids.

Question 51

Which type of lipid molecule is characterized by a backbone of four fused rings?

A) DNA
B) phospholipid
C) triglyceride
D) steroid
E) amino acid

Question 52

The proposed cause of CJD and kuru in humans,mad cow disease,and scrapie in sheep is a change in a brain protein.Disease victims appear to have a protein that should normally contain alpha helices but instead they have changed into a protein made of beta pleated sheets.The disease appears to spread when the abnormal protein comes into contact with the normal protein,causing it to become deformed.Which level of protein structure is associated with these diseases?

A) primary
B) secondary
C) tertiary
D) quaternary
E) molecular

Question 53

Two glucose molecules can combine to form a disaccharide molecule and

A) another glucose molecule.
B) another disaccharide molecule.
C) a dipeptide molecule.
D) a lipid molecule.
E) a water molecule.

Question 54

The final shape of a protein is very important to its function.When proteins undergo an irreversible change in shape called ________________ they ________________ perform their usual functions.

A) naturation/can
B) naturation/cannot
C) denaturation/can
D) denaturation/cannot
E) dehydration reaction/cannot

Question 55

Glycogen is a

A) monosaccharide used for quick energy.
B) protein found in cell membranes.
C) polysaccharide used to store glucose/energy.
D) fat found in margarine.
E) nucleic acid found in the nucleus of a cell.

Question 56

Which of the following types of lipid is the most abundant constituent of cell membranes?

A) cholesterol
B) phospholipid
C) triglyceride
D) neutral fat
E) fat

Question 57

The backbone of a nucleic acid strand is composed of

A) glycerol.
B) "R" groups.
C) nitrogenous bases.
D) alternating pentose sugars and phosphate groups.
E) alternating adenines and thymines.

Question 58

____ is a polysaccharide that is found in plant cell walls and accounts for their strength.

A) Cellulose
B) Chitin
C) Glycogen
D) Starch
E) Cholesterol

Question 59

All carbohydrate molecules

A) contain amino acids.
B) contain nitrogen and phosphate.
C) are organic acids.
D) are composed of atoms of C, H, and the functional group -OH.
E) are composed of atoms of C, H, O, and N.

Question 60

The primary function of carbohydrates is

A) quick fuel and short-term energy storage.
B) structural reinforcement of plant and fungal cell walls.
C) encoding the hereditary information.
D) to speed chemical reactions in cells.
E) to transport molecules across cell membranes.

Question 61

Cholesterol is a component of cell membranes and is an example of which type of lipid?

A) steroids
B) phospholipids
C) fatty acids
D) triglycerides
E) oils

Question 62

Determine what would happen to an individual's proteins if they developed a fever of 103^o F for several days.

A) The proteins would denature due to the increase in body temperature and would become unable to function correctly.
B) The proteins would increase in their ability to perform their functions because of the increase in body temperature.
C) Nothing would happen to the proteins as a result of the increase in temperature.
D) The proteins would denature due to the increase in body temperature and would increase in their ability to function correctly.
E) One protein would alter in shape which would then cause the next protein to alter in shape which would cause a third protein to alter in shape and so forth until all of the proteins were altered in shape.

Question 63

Which statement about the cellular nucleic acids DNA and RNA is incorrect?

A) DNA is double-stranded, and RNA is single-stranded.
B) The sugar in DNA is deoxyribose, and in RNA the sugar is ribose.
C) DNA has a helix shape; RNA does not.
D) RNA and DNA have the same four nitrogen-containing bases.
E) Both DNA and RNA are polymers of nucleotides.

Question 64

Which of the following reactions is most likely to occur if an individual was to ingest a large dose of lemon juice?

A) There would be an increase in the amount of carbonic acid within the blood stream. If the carbonic acid didn't not form then the pH of the individual's blood could shift toward 7.2.
B) There would be an decrease in the amount of carbonic acid within the blood stream. If the carbonic acid didn't not form then the pH of the individual's blood could shift toward 7.2.
C) There would be an increase in the amount of carbonic acid within the blood stream. If the carbonic acid didn't not form then the pH of the individual's blood could shift toward 7.8.
D) There would be a decrease in the amount of carbonic acid within the blood stream. If the carbonic acid didn't not form then the pH of the individual's blood could shift toward 7.2.
E) There would be a decrease in the amount of carbonic acid within the blood stream. If the carbonic acid didn't not form then the pH of the individual's blood could shift toward 7.8.

Question 65

Which of the following sequences correctly lists the bonds in order of strongest to weakest?

A) double covalent - single covalent - ionic - hydrogen
B) single covalent - double covalent - ionic - hydrogen
C) ionic- double covalent - single covalent - hydrogen
D) hydrogen - double covalent - single covalent - ionic
E) double covalent - single covalent - hydrogen - ionic

Question 66

What type of reaction is necessary to produce a dipeptide from individual amino acids?

A) dehydration reaction
B) hydrolysis reaction
C) denaturation
D) Dipeptides are not formed from amino acids.
E) None of these reactions will form a dipeptide.

Question 67

Which type of bond formation is responsible for the properties of water?

A) hydrogen
B) polar covalent
C) ionic
D) nonpolar covalent
E) None of these bonds play a role in the properties of water.

Question 68

Which of the following is not a function of ATP within the cell?

A) All of these are functions of ATP within the cell.
B) Conduction of nerve impulses.
C) Contraction of muscle cells.
D) Synthesis of macromolecules.
E) Energy currency of the cell.

Question 69

Which functional groups are associated with a dehydration reaction?

A) H & OH
B) H & SH
C) OH & NHH
D) SH & OH
E) COOH & SH

Question 70

Which group of lipids will contain hydrophilic heads that face outwards and hydrophobic tails that face inwards that will form a barrier?

A) phospholipids
B) steroids
C) triglycerides
D) saturated acids
E) trans-fatty acids

Question 71

Which nutrient source is the easiest one for humans to breakdown and form ATP?

A) glucose
B) protein
C) cellulose
D) phospholipids
E) chitin

Question 72

Removal of the hydroxyl functional group would disrupt the structure of _________.

A) sugars and some amino acids
B) sugars
C) fatty acids and amino acids
D) nucleotides and phospholipids
E) nucleotides and fatty acids

Question 73

During the formation of a polymer,two monomers are joined by the removal of a _______ & _______.

A) OH, H
B) OH, SH
C) H, COH
D) COOH, SH
E) NHH, COOH

Question 74

Which of the following subatomic particles will be found within the nucleus of the atom?

A) protons & neutrons
B) protons & electrons
C) electrons & neutrons
D) only neutrons
E) only protons

Question 75

Which of the following radiation uses is the one that is most likely to have beneficial and harmful consequences?

A) Using radiation to treat a cancer patient.
B) Using radiation to sterilize mail.
C) Using radiation to sterilize surgical equipment prior to a surgery.
D) Radiating fruits and vegetables prior to storage.
E) All of these will have beneficial and harmful consequences.

Question 76

Which of the following radioactive isotopes are used to detect whether or not an individual has a healthy thyroid?

A) I¹³¹
B) C¹⁴
C) glucose
D) H₂
E) All of the above can be used.

Question 77

What type of bond will connect the amino acids in a protein?

A) peptide
B) triple covalent
C) polar covalent
D) ionic
E) double covalent

Question 78

Briefly describe how ATP is broken down and turned into ADP.

Question 79

Which of the following functional groups is present in amino acids?

A) SH
B) NHH
C) COOH
D) OH
E) All of these are present in amino acids.

Question 80

Briefly describe the major functions of lipids in the human body.