Deck 4: Carbon and the Molecular Diversity of Life

Question 1

Differences among organisms are caused by differences in the ________.

A) elemental composition from organism to organism
B) types and relative amounts of organic molecules synthesised by each organism
C) sizes of the organic molecules in each organism
D) types of inorganic compounds present in each organism

Answer 1

B

Question 2

Which of the following statements correctly describes cis-trans isomers?

A) They have variations in arrangement around a double bond.
B) They have an asymmetric carbon that makes them mirror images.
C) They have the same chemical properties.
D) They have different molecular formulas.

Answer 2

A

Question 3

Stanley Miller's 1953 experiments supported the hypothesis that ________.

A) life on Earth arose from simple inorganic molecules
B) organic molecules can be synthesised abiotically under conditions that may have existed on early Earth
C) life on Earth arose from simple organic molecules, with energy from lightning and volcanoes
D) the conditions on early Earth were conducive to the origin of life

Answer 3

B

Question 4

Each bond in carbon dioxide represents ________.
$\mathrm { O } = \mathrm { C } = \mathrm { O }$

A) one resonating electron
B) a pair of shared electrons
C) two pairs of shared electrons
D) a pair of protons

Question 5

The experimental approach taken in current biological investigations presumes that ________.

A) simple organic compounds can be synthesised in the laboratory from inorganic precursors, but complex organic compounds like carbohydrates and proteins can be synthesised only by living organisms
B) a life force ultimately controls the activities of living organisms, and this life force cannot be studied by physical or chemical methods
C) living organisms are composed of the same elements present in nonliving things, plus a few special trace elements found only in living organisms or their products
D) living organisms can be understood in terms of the same physical and chemical laws that can be used to explain all natural phenomena

Question 6

Compared to a hydrocarbon chain where all the carbon atoms are linked by single bonds, a hydrocarbon chain with the same number of carbon atoms but with one or more double bonds will ________.

A) be more flexible in structure
B) be more constrained in structure
C) be more polar
D) have more hydrogen atoms

Question 7

Which of the following carbon molecules does not have the bond angle of 109.5°?

A) CH₄
B) C2H4
C) C2H6
D) C3H8

Question 8

A carbon atom is most likely to form what kind of bond(s) with other atoms?

A) ionic
B) hydrogen
C) covalent
D) ionic bonds, covalent bonds, and hydrogen bonds

Question 9

The complexity and variety of organic molecules is due to ________.

A) the chemical versatility of carbon atoms
B) the variety of rare elements in organic molecules
C) the diverse bonding patterns of nitrogen
D) their interaction with water

Question 10

Miller's classic experiment demonstrated that a discharge of sparks through a mixture of gases could result in the formation of a large variety of organic compounds. Miller did not use ________ as one of the gases in his experiment.

A) methane
B) oxygen
C) water
D) ammonia

Question 11

Why are hydrocarbons insoluble in water?

A) The majority of their bonds are polar covalent carbon-to-hydrogen linkages.
B) The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages.
C) They exhibit considerable molecular complexity and diversity.
D) They are less dense than water.

Question 12

Research indicates that ibuprofen, a drug used to relieve inflammation and pain, is a mixture of two enantiomers; that is, molecules that ________.

A) have identical chemical formulas but differ in the branching of their carbon skeletons
B) are mirror images of each other
C) differ in the location of their double bonds
D) differ in the arrangement of atoms around their double bonds

Question 13

Why is carbon so important in biology?

A) It is a common element on Earth.
B) It has very little electronegativity, making it a good electron donor.
C) It bonds to only a few other elements.
D) It can form a variety of carbon skeletons and host functional groups.

Question 14

A carbon atom has 6 electrons however, its valency is 4. This is because the carbon atom ________.

A) donates its 2 electrons to another atom
B) shares its 2 electrons and bonds with another atom
C) has 4 electrons in its first shell and 2 in the second shell
D) has only 2 electrons in its first shell and 4 in the second shell

Question 15

The kind and number of bonds an atom can form depends on ________.

A) its atomic number
B) its electron configuration
C) its atomic mass
D) the number of particles in its nucleus

Question 16

In an ethane (C2H6) molecule, each carbon atom is bonded to ________ hydrogen atoms.

A) two
B) three
C) four
D) six

Question 17

The element present in all organic molecules is ________.

A) hydrogen
B) oxygen
C) carbon
D) nitrogen

Question 18

What determines whether a carbon atom's covalent bonds to other atoms are in a tetrahedral configuration or a planar configuration?

A) the presence or absence of bonds with oxygen atoms
B) the presence or absence of double bonds between the carbon atom and other atoms
C) the polarity of the covalent bonds between carbon and other atoms
D) the solvent in which the organic molecule is dissolved

Question 19

Which of the following is true of carbon?

A) It forms only polar molecules.
B) It can form a maximum of three covalent bonds with other elements.
C) It is highly electronegative.
D) It can form both polar and nonpolar bonds.

Question 20

How many electrons does one atom of carbon share to complete its valence shell?

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

Question 21

Which two functional groups are always found in amino acids?

A) carbonyl and amino groups
B) carboxyl and amino groups
C) amino and sulfhydryl groups
D) hydroxyl and carboxyl groups

Question 22

Use the following figure to answer the question. The two molecules shown in the figure are best described as ________.

A) enantiomers
B) radioactive isotopes
C) structural isomers
D) cis-trans isomers

Question 23

Which of the functional groups is not reactive but serves as a recognisable tag on the DNA molecule and alter the expression of genes in the cells?

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

Question 24

Which of the following illustrations is not a structural isomer of an organic compound with the molecular formula C6H14? For clarity, only the carbon skeletons are shown; hydrogen atoms that would be attached to the carbons have been omitted.

A)

B)

C)

D)

Question 25

Which of the following molecules is polar?
C3H7OH C2H5COOH

A) C3H7OH and C2H5COOH are both polar molecules.
B) Neither C2H5COOH or C3H7OH is polar.
C) C2H5COOH is polar, but C3H7OH is not polar.
D) C2H5COOH is not polar, but C3H7OH is polar.

Question 26

Which of the pairs of molecular structures shown depict enantiomers (enantiomeric forms) of the same molecule?

A)

B)

C)

D)

Question 27

A. $- \mathrm { OH }$
B.
C. $- \mathrm { NH } _ { 2 }$
D. $- \mathrm { SH }$

- Which of the groups is an acidic functional group that can dissociate and release H? into a solution?

A) A
B) B
C) C
D) D

Question 28

A. $- \mathrm { OH }$
B.
C. $- \mathrm { NH } _ { 2 }$
D. $- \mathrm { SH }$

- Which of the functional groups shown helps stabilise proteins by forming covalent cross-links within or between protein molecules?

A) A
B) B
C) C
D) D

Question 29

Use the figure to answer the question. What is the name of the functional group shown in the figure?

A) carbonyl
B) ketone
C) aldehyde
D) carboxyl

Question 30

Organic molecules with only hydrogens and five carbon atoms cannot ________.

A) have a branching carbon skeleton
B) have different combinations of double bonds between carbon atoms
C) have different positions of double bonds between carbon atoms
D) form enantiomers

Question 31

Amino acids are acids because they always possess ________ as the functional group.

A) amino
B) carbonyl
C) carboxyl
D) phosphate

Question 32

Use the following figure to answer the question. The figure shows the structures of glucose and fructose. These two molecules are ________.

A) isotopes
B) enantiomers
C) cis-trans isomers
D) structural isomers

Question 33

Testosterone and estradiol are male and female sex hormones, respectively, in many vertebrates. In what way(s) do these molecules differ from each other? Testosterone and estradiol ________.

A) are structural isomers but have the same molecular formula
B) are cis-trans isomers but have the same molecular formula
C) have different functional groups attached to the same carbon skeleton
D) are enantiomers of the same organic molecule

Question 34

A. $- \mathrm { OH }$
B.
C. $- \mathrm { NH } _ { 2 }$
D. $- \mathrm { SH }$

- Which of the functional groups shown is present in ethanol but not in ethane?

A) A
B) B
C) C
D) D

Question 35

Use the following figure to answer the question. The figure shows the structures of glucose and fructose. These two molecules differ in the ________.

A) number of carbon, hydrogen, and oxygen atoms
B) types of carbon, hydrogen, and oxygen atoms
C) arrangement of carbon, hydrogen, and oxygen atoms
D) number of oxygen atoms joined to carbon atoms by double covalent bonds

Question 36

A compound contains hydroxyl groups as its predominant functional group. Therefore, this compound ________.

A) lacks an asymmetric carbon and is probably a fat or lipid
B) should dissolve in water
C) should dissolve in a nonpolar solvent
D) will not form hydrogen bonds with water

Question 37

Some carbon skeletons have different numbers and locations of double bonds to ________.

A) add molecular complexity and diversity that characterise living matter
B) be more flexible that makes the molecule stronger
C) stay in its liquid state
D) increase its solubility in water

Question 38

A. $- \mathrm { OH }$
B.
C. $- \mathrm { NH } _ { 2 }$
D. $- \mathrm { SH }$

- Which functional group shown can pick up protons and raise the pH of the surrounding solution?

A) A
B) B
C) C
D) D

Question 39

Use the figure to answer the question. Thalidomide and L-dopa (see figure) are examples of pharmaceutical drugs that occur as enantiomers, or molecules that ________.

A) have identical three-dimensional shapes
B) are mirror images of one another
C) are mirror images of one another and have the same biological activity
D) are cis-trans isomers

Question 40

Use the following figure to answer the question. The two molecules shown in the figures are best described as ________.

A) enantiomers
B) structural isomers
C) cis-trans isomers
D) chain length isomers

Question 41

Which of the following statements is true?

A) ADP contains more energy than ATP.
B) Following hydrolysis, ATP can give off one phosphate, whereas ADP cannot.
C) ADP can have two positive charges.
D) ATP can have four negative charges.

Question 42

A.
B.
C.
D.

- Which molecule shown contains a carboxyl group?

A) A
B) B
C) C
D) D

Question 43

Which chemical group is most likely to be responsible for an organic molecule behaving as a base?

A) hydroxyl
B) carbonyl
C) amino
D) phosphate

Question 44

A.
B.
C.
D.

-Which molecules shown contain a carbonyl group?

A) A and B
B) B and C
C) B, C and D
D) C and D

Question 45

A.
B.
C.
D.

-Which molecule can be a result of mercaptoethanol reduction of a disulphide bridge?

A) A
B) B
C) C
D) D

Question 46

A.
B.
C.
D.

-Which molecule shown can increase the concentration of hydrogen ions in a solution and is therefore an organic acid?

A) A
B) B
C) C
D) D

Question 47

A.
B.
C.
D.

-Which molecule has at least one carbon atom attached to three different chemical groups?

A) A
B) B
C) D
D) A and B

Question 48

Choose the term that correctly describes the relationship between these two sugar molecules:

A) structural isomers
B) cis-trans isomers
C) enantiomers
D) isotopes

Question 49

Organic chemistry is currently defined as

A) the study of compounds made only by living cells.
B) the study of carbon compounds.
C) the study of natural (as opposed to synthetic) compounds.
D) the study of hydrocarbons.

Question 50

Use the figures to answer the question. A.
B.
C.
D. Which molecule(s) shown is (are) ionised in a cell?

A) A
B) B and D
C) C and D
D) D

Question 51

A.
B.
C.
D.

- Which molecule shown is a thiol?

A) A
B) B
C) C
D) D

Question 52

Which functional group is not present in this molecule?

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

Question 53

Visualise the structural formula of each of the following hydrocarbons. Which hydrocarbon has a double bond in its carbon skeleton?

A) C₃H₈
B) C₂H₆
C) C₂H₄
D) C₂H₂

Question 54

Which action could produce a carbonyl group?

A) the replacement of the -OH of a carboxyl group with hydrogen
B) the addition of a thiol to a hydroxyl
C) the addition of a hydroxyl to a phosphate
D) the replacement of the nitrogen of an amine with oxygen

Question 55

A.
B.
C.
D.

- Which molecule shown above contains a functional group that is a part of the molecule known as the "energy currency of living organisms"?

A) A
B) B
C) C
D) D

Question 56

A.
B.
C.
D.

- Which molecule shown has a carbonyl functional group in the form of an aldehyde?

A) A
B) B
C) C
D) D

Question 57

Which of the following molecules is a part of ATP?

A) adenosine
B) cytosine
C) guanine
D) uracil

Question 58

A.
B.
C.
D.

- Which molecule shown above can contribute negative charge when positioned in a chain?

A) A
B) B
C) C
D) D