quiz questions

Question 1

A covalent chemical bond is one in which

Answer 1

outer-shell electrons of two atoms are shared so as to satisfactorily fill the outer electron shells of both atoms.

Question 2

An atom with atomic number 12 would have what type of chemical behavior in bonding with other elements?

Answer 2

It would form ions with a +2 charge

Question 3

In ammonium chloride salt (NH4Cl) the anion is a single chloride ion, Cl. What is the cation of NH4Cl?

Answer 3

NH4, with a charge of +1

Question 4

Liquid water’s high specific heat is mainly a consequence of the

Answer 4

absorption and release of heat when attractions due to opposite partial charges break and form.

Question 5

What bond forms when the differences of electronegativity between atoms in a molecule is greater than 2.0?

Answer 5

an ionic bond

Question 6

The atomic number of sulfur is 16. Sulfur combines with hydrogen by covalent bonding to form a compound, hydrogen sulfide. Based on the number of valence electrons in a sulfur atom, predict the molecular formula of the compound:

Answer 6

H2S

Question 7

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

Answer 7

Four

Question 8

Ice is used to cool beverages primarily because

Answer 8

it absorbs heat as the number of hydrogen bonds decrease from the solid to liquid state.

Question 9

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

Answer 9

both of the monomers.

Question 10

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.

Answer 10

more neutrons than

Question 11

Which of the following is an impossibly covalently bonded molecule?

Answer 11

Oxygen can only have 2 bonds

Question 12

Which of the following molecules is entirely hydrophobic?

Answer 12

CH4

Question 13

A molecule with the formula C18H36O2 is probably a

Answer 13

fatty acid.

Question 14

Molecules with which functional groups may form polymers via dehydration reactions?

Answer 14

either hydroxyl or carboxyl groups

Question 15

What type of covalent bond between amino acid side chains (R groups) functions in maintaining a polypeptide’s specific three-dimensional shape?

Answer 15

disulfide bond

Question 16

The R group or side chain of the amino acid serine is –CH2–OH. The R group or side chain of the amino acid leucine is –CH2–CH–(CH3)2. Where would you expect to find these amino acids in a globular protein in aqueous solution?

Answer 16

Leucine would be in the interior, and serine would be on the exterior of the globular protein.

Question 17

If cells are grown in a medium containing radioactive 35S, which of these molecules will be labeled?

Answer 17

proteins

Question 18

DNAase is an enzyme that catalyzes the hydrolysis of the covalent bonds that join nucleotides together. What would first happen to DNA molecules treated with DNAase?

Answer 18

The phosphodiester bonds between deoxyribose sugars and phosphate groups would be broken.

Question 19

If a DNA sample were composed of 10% thymine, what would be the percentage of guanine?

Answer 19

40

Question 20

If one strand of a DNA molecule has the sequence of bases 5’ATTGCA3’, the other complementary strand would have the sequence

Answer 20

5’TGCAAT3’.

Question 21

What is the structural feature that allows DNA to replicate?

Answer 21

complementary pairing of the nitrogenous bases

Question 22

Amylase, a hydrolytic enzyme, is added to a starch solution at optimal pH and temperature for the reaction. After 3 hours no starch is present. How can the experiment be changed so that there is no starch present after just 1 hour.

Answer 22

Add more amylase

Question 23

Lipase is a digestive enzyme that catalyzes the hydrolysis of ester linkages in triacylglycerols in the small intestine. In the laboratory, how can the activity of lipase be measured?

Answer 23

By measuring a decline in pH due to the carboxyl group on the fatty acids.

Question 24

The 1974 Nobel prize for Medicine was awarded to Gerty and Carl Cori following their isolation and characterization of the two enzymes needed for glycogen synthesis. Why are two enzymes required to produce glycogen in animals?

Answer 24

One enzyme catalyzes the 1,4 glycosidic bond and the other enzyme catalyzes the 1,6 glycosidic bond where the glycogen molecule branches.