Deck 2: The Molecules of Cells

Question 1

A covalent bond is

A) a type of bond that results in ionic compounds.
B) formed from 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 1

C

Question 2

The isotope shown below has $${ } _ { 6 } ^ { 14 } \mathrm { C }$$

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

Answer 2

8 neutrons.

Question 3

If neutral atoms become positive ions, they

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

Answer 3

B

Question 4

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 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

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 7

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 8

The two isotopes shown below differ in the number of $${ } _ { 6 } ^ { 12 } \text { C } { } _ { 6 } ^ { 14 } \text { C }$$

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

Question 9

Which of the following is an example of a compound?

A) O₂
B) Cl
C) H₂
D) C₆H₁₂O₆
E) Na⁺

Question 10

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 11

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

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

Question 12

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 13

The atomic mass of an element

A) is determined by the number of protons and neutrons contained in the nucleus.
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 14

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 15

Which of the following statements is true of chemical bonds?

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

Question 16

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.

Question 17

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 18

Isotopes of a given element have

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

Question 19

Which of the following statements about hydrogen bonding is correct?

A) Hydrogen bonding occurs only between water molecules.
B) Hydrogen bonds are difficult to break.
C) Hydrogen bonding can occur between different molecules or within the same molecule.
D) Hydrogen bonding is only common among small molecules.
E) Hydrogen bonding is usually represented by a solid line between atoms.

Question 20

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 21

The pH of blood is slightly alkaline. 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 22

Buffers

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

Question 23

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 24

Since pure water is neutral in pH, 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 25

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 26

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 27

Potassium hydroxide (KOH) almost completely dissociates in aqueous solution into K⁺ and OH^-, which means it is a(n)

A) acid.
B) base.
C) has no effect on pH.
D) polar covalent molecule.
E) nonpolar covalent molecule.

Question 28

Rain falling in the northeastern United States has a pH between 5.0 and 4.0. Normally, rainwater has a pH of about 5.6. Which of the following statements is 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 decreased.
D) The proportion of hydroxide ions (OH^-) in the rainwater has increased.
E) The rainwater with a pH of 4.0 is a thousand times more acidic than the rainwater with a pH of 5.0.

Question 29

Aspirin is acetyl salicylic acid and can therefore pose a problem to people who have ulcers. Bufferin is an alternative to aspirin that 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⁺) or hydroxide (OH^-) ions.

Question 30

Which of the following molecules is inorganic?

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

Question 31

In water, a weak hydrogen bond occurs between a 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 32

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 33

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 34

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 35

Which of the following is a property of water that results from hydrogen bonding?

A) The temperature of water changes very quickly.
B) Many nonpolar substances dissolve in water.
C) Water molecules are cohesive.
D) Water is densest at 0°C.
E) Water has a low surface tension.

Question 36

Hydrogen bonding produces which of the following properties of water?

A) Water boils at a lower temperature than expected.
B) Ice is less dense than liquid water.
C) Water absorbs heat with a large change in temperature.
D) Water releases heat with a large change in temperature.
E) Land areas with an abundance of water have more extreme temperatures than land areas that are lacking water.

Question 37

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 38

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 39

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 40

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 41

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 42

The molecular structure shown here is

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

Question 43

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

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

Question 44

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 45

Nucleic acids are polymers of

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

Question 46

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 47

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 48

Maltose is classified as a

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

Question 49

Hydrolysis of a fat results in

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

Question 50

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 51

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 must be the causative agent. If a virus was 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? •Amylase digests carbohydrates; tissue filtrate still infects healthy test animal.
•Lipase digests fats; tissue filtrate still infects healthy test animal.
•Formaldehyde and/or heat denatures DNA and RNA; tissue filtrate still infects healthy test animal.
•Trypsin digests protein; tissue filtrate does not infect healthy test animal.

A) carbohydrate
B) fat
C) protein
D) DNA or RNA
E) carbohydrate, fat, or DNA or RNA; but not protein

Question 52

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

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

Question 53

The ________ structure of a protein consists of a strand of amino acids forming an alpha helix or pleated sheet.

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

Question 54

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 55

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 56

When two glucose molecules combine, they 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 57

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 58

Enzymes are organic compounds classified as

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

Question 59

________ 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 60

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 61

Which statement about DNA and RNA is correct?

A) DNA is single-stranded, and RNA is double-stranded.
B) The sugar in DNA is ribose, and in RNA the sugar is deoxyribose.
C) RNA has a helix shape; DNA does not.
D) The base uracil is unique to RNA and the base thymine unique to DNA.
E) DNA is a nucleotide polymer while RNA is a carbohydrate polymer.

Question 62

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 answer choices can be used.

Question 63

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

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

Question 64

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 the answer choices will form a dipeptide.

Question 65

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 66

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

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

Question 67

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 68

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

Question 69

Which group of lipids forms a barrier around cells?

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

Question 70

Which functional group(s) is/are associated with a dehydration reaction?

A) OH
B) SH
C) OH and NH
D) SH and OH
E) COOH and SH

Question 71

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 72

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

Question 73

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

Question 74

Which of the following radiation uses is the one that is most likely to have both 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 the answer choices will have beneficial and harmful consequences.

Question 75

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

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

Question 76

Removal of the sulfhydryl functional group would disrupt the structure of

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

Question 77

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 78

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

A) sulfhydryl
B) amino
C) carboxyl
D) hydroxyl
E) All of the answer choices are present in amino acids.

Question 79

Which of the following is a function of ATP within the cell?

A) conduction of nerve impulses
B) contraction of muscle cells
C) synthesis of macromolecules
D) energy currency of the cell
E) All of the answer choices are functions of ATP within the cell.