HOMEWORK CHAPTER 15 – In which solvent would lipids be

1) In which solvent would lipids be most soluble?

a) hexane

b) water

c) methyl alcohol

d) ethyl alcohol

2) Triglycerides composed of glycerin and mostly polyunsaturated fatty acid residues are likely to be ___ at room temperature.

a) solid fats

b) liquid oils

c) gases

d) waxes

3) Shown below is the structure of the fatty acid, lauric acid:

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

C

OH

O

H3C

The boxed portion is considered to be both

a) hydrophilic and hydrophobic.

b) polar and hydrophobic.

c) polar and hydrophilic.

d) nonpolar and hydrophilic.

4) The structure of the fatty acid, palmitic acid, is

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

C

OH

O

CH2

CH2

CH2

CH2

H3C

Palmitic acid is a(n) ___ fatty acid.

a) saturated

b) monounsaturated

c) polyunsaturated

d) waxy

 

 

5) The fatty acid, palmitoleic acid, is

CH2

CH

CH

CH2

CH2

CH2

CH2

CH2

CH2

CH2

C

OH

O

CH2

CH2

CH2

CH2

CH2

H3C

Notice the double bond. Palmitoleic acid is a ___ fatty acid.

a) saturated

b) monounsaturated

c) polyunsaturated

d) waxy

6) Fatty acids can produce ions that are ___.

a) highly charged at the tail

b) nonpolar

c) amphipathic

d) hydrophobic

7) A saturated fatty acid is

a) a fatty acid with a carbon chain which has just one carbon-carbon double bond.

b) a fatty acid chain in which a carbon chain has two or more carbon-carbon double bonds.

c) a fatty acid which has all single carbon-carbon bonds joining carbon atoms.

d) a fatty acid with cis-carbon-carbon double bonds.

8) The melting point of lauric acid, CH3(CH2)10CO2H , is 43?C and the melting point of

stearic acid (CH3(CH2)16CO2H) is 69?C. Which of the following statements best explains

why the melting point of lauric acid is lower than the melting point of stearic acid?

a) The hydrophobic tail of lauric acid is longer than the hydrophobic tail of stearic acid.

b) Stearic acid is soluble in water and lauric acid is not soluble in water.

c) Stearic acid is a fatty acid, whereas lauric acid is not a fatty acid.

d) The London force interactions are stronger in stearic acid than they are in lauric acid.

9) The skeletal structure of Arachidonic acid, an essential fatty acid, is provided below.

Arachidonic acid is best classified as:

OH

O

a) Omega-3-fatty acid

b) Omega-6-fatty acid

c) Saturated fatty acid

d) Wax

10) In which solvent below would lipids be least soluble?

a) hexane

b) water

c) methyl alcohol

d) ethyl alcohol

11) The structure of palmitate ion derived from the fatty acid, palmitic acid, is

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

C

OH

O

CH2

CH2

CH2

CH2

H3C

Its molecular structure has both polar and nonpolar portions. Therefore, palmitate ion is

classified as ___.

a) hydrophobic

b) lipophobic

c) hydrophilic

d) amphipathic

12) Omega-3 and Omega-6-fatty acids are essential fatty acids. Which of the following

statement best describes these essential fatty acids?

a) They are very soluble in water.

b) They are saturated fatty acids that the body absorbs faster.

c) They are not produced in the body and must be obtained through diet.

d) They are waxes found in the body.

13) The skeletal structure of docosahexaenoic acid, an essential fatty acid, is provided

below. Docosahexaenoic acid is best classified as:

HO

O

a) Omega-3-fatty acid

b) Omega-6-fatty acid

c) Saturated fatty acid

d) Wax

14) The structure below is best classified as a ___.

CH3(CH2)13CH2C OCH2(CH2)28CH3

O

a) triglyceride

b) wax

c) steroid

d) phospholipid

15) Waxes are compounds that are

a) the result of the reaction of a fatty acid and sodium hydroxide.

b) extremely hydrophilic due to the head end of the compound.

c) mixtures of water insoluble compounds, especially esters.

d) small compounds produced when short chain fatty acids react with an alcohol.

16) Compounds found in feathers and leaves of most plants, which serve as protective

coatings to keep water from entering or leaving an organism, are ___.

a) glycolipids

b) steroids

c) waxes

d) sphingolipids

17) Carnauba wax is widely used for high-gloss car and floor polishes. A major component

of carnauba wax ester is provided below. The condensed structure of the alcohol from

which carnauba wax ester is formed is:

CH3(CH2)30 C

O

O(CH2)33CH3 B

CH3(CH2)29OH

A.

B.

CH3(CH2)30C

O

OH

CH3(CH2)30CH2OH

CH3(CH2)33OH

C.

D.

18) Identify the class of lipid to which the following molecule belongs.

CH2

CH2 O

O

O

O C

O

C

O

C

CH

(CH2)6

(CH2)7CH CH (CH2)7

(CH2)6

(CH2 CH CH)2 (CH2)4 CH3

CH3

(CH2 CH CH)3 CH2 CH3

a) fatty acid

b) triglyceride

c) wax

d) glycerophospholipid

19) Saponification

a) is a hydrolysis reaction.

b) results in the production of triglycerides.

c) is used to store energy for later use.

d) is a reaction found in plant metabolism.

20) How many molecules of H2 will react with one molecule of the following triglyceride?

CH2

CH2 O

O

O

O C

O

C

O

C

CH

(CH2)14CH3

(CH2)7CH CH(CH2)7CH3

(CH2)16CH3

a) 1

b) 3

c) 4

d) 6

21) The effect of the hydrogenation of oils is to

a) remove double bonds.

b) cause the oils to remain as liquids.

c) make the oils boil at a lower temperature.

d) make the oils oxidize.

22) Oleic acid has the formula CH3(CH2)7(CH = CH(CH2)7CO2H. The carbon –carbon

double bond in oleic acid is usually cis. Compared to saturated fatty acids with the same

number of carbon atoms, cis-oleic acid will have

a) a lower melting point due to a kink in the hydrocarbon tail.

b) stronger London forces and a higher melting point.

c) bonds that fit in the packing of the hydrophobic tails, creating stronger interaction between

molecules.

d) no reaction with hydrogen in the presence of platinum catalyst.

23) Animal fats and vegetable oils become rancid when exposed to air because

a) they are hydrogenated to form saturated fatty acids.

b) carbon-carbon double bonds are oxidized in air, producing small organic molecules.

c) they form amino acids in air.

d) they are partially hydrogenated.

24) Identify the class of lipid to which the following molecule belongs.

CH2

CH2 O

O

O

O C

O

C

O

CH

(CH2)10CH3

(CH2)10CH3

P O (CH2)2 N(CH3)3

+

a) sphingophospholipid

b) triglyceride

c) cholesterol

d) glycerophospholipid

25) Which of the following is one of the products formed when the lipid below is

saponified? B

CH2

CH2 O

O

O

O C

O

C

O

C

CH

(CH2)14CH3

(CH2)7CH CH(CH2)7CH3

(CH2)16CH3

CH3(CH2)14

O

C O

CH3(CH2)16

O

C H

CH3(CH2)7CH CH(CH2)7CH3

CH3(CH2)16

O

C

A

B

C

D CH3

26) Phospholipids ___.

a) are really a wax

b) are very polar on both ends

c) contain a sugar, which may be simple or a chain

d) are part of the structure of cell membranes

27) The structure of glycerophospholipids contains

a) a phosphate group, glycerol, three fatty acids, and a sugar molecule.

b) a phosphate group, glycerol, two fatty acids, and an alcohol molecule.

c) a phosphate group, a cyclic carbon ring, and variable numbers of fatty acids.

d) a phosphate group, a carbohydrate molecule, an alcohol, and fatty acids.

28) Determine the number of molecules of H2 that will react with one molecule of the

following triglyceride.

CH2

CH2 O

O

O

O C

O

C

O

C

CH

(CH2)6

(CH2)7CH CH (CH2)7

(CH2)6

(CH2 CH CH)2 (CH2)4 CH3

CH3

(CH2 CH CH)3 CH2 CH3

a) three

b) four

c) six

d) five

29) Because of the components that are found in phospholipids, the phospholipid molecules

a) are long molecules with multiple polar points.

b) have a head that is nonpolar, as is the tail.

c) have a polar end and a nonpolar end.

d) have two ends that are nonpolar with a polar middle.

30) The phosphate head group of phospholipids is ___ and is found on the ___ of a

membrane’s lipid bilayer.

a) hydrophilic/inside

b) hydrophilic/outside

c) hydrophobic/inside

d) hydrophobic/outside

31) The difference between the sphingolipids and the glycerophospholipids is that the sphingolipids

a) have three alcohol residues that replace the fatty acid residues.

b) have one phosphate, but it is attached to the fatty acid residue, not the glycerol.

c) have three phosphates, not one, and they are attached to all of the fatty acids.

d) include sphingosine with a phosphate attached to it, and an alcohol residue.

32) The glycolipid molecule is characterized by having a specific residue attached to the

backbone. Which is that residue?

a) phosphate

b) glycerol

c) lipid

d) sugar

33) The lipid that is a cell surface receptor for hormones and drugs is a

a) glycerophopholipid.

b) ganglioside.

c) sphingomyelin.

d) cerebroside.

34) Lecithin is found in egg whites and can be used as an emulsifying agent to keep

mayonnaise from separating. Lecithin is classified as a ___.

a) phospholipid

b) wax

c) steroid

d) glycolipid

35) Sphingomyelins are found in ___.

a) waxes

b) egg whites

c) skin cells

d) nerve cell membranes

36) How many products are obtained when the phospholipid below is saponified?

CH2

CH2 O

O

O

O C

O

C

O

CH

(CH2)16CH3

(CH2)7CH=CH(CH2)7CH3

P O (CH2)2 N(CH3)3

+

O

a) 2

b) 5

c) 3

d) 6

37) The structure shown below represents which of the following?

HO CH CH CH(CH2)12CH3

CH NH3

CH2 OH

+

a) sphingosine

b) glycerophospholipid

c) triglyceride

d) sphingoglycolipid

38) The structure shown below represents which of the following?

a) sphingophospholipid

b) shingoglycolipid

c) glycerophospholipid

d) disaccharide

39) The structure shown below is the skeletal structure of a ___.

a) wax

b) triglyceride

c) phospholipid

d) steroid

40) The steroid that is the raw material for the production of other steroids is

a) triglyceride.

b) cholesterol.

c) progesterone.

d) eicosanoid.

41) The hormone that is the starting point for the production of the adrenocorticoid

hormones and testosterone is

a) progesterone.

b) estrogen.

c) cholesterol.

d) chylomicrons.

42) Which of the following is released from the gallbladder into the small intestine to aid

digestion by dispersing dietary lipids into fine emulsions?

a) Bile salts

b) cholesterol

c) eicosanoids

d) phospholipids

47) ___ is the eicosanoid involved in blood clotting.

a) Prostaglandin

b) Leukotriene

c) Progesterone

d) Thromboxane

48) ___ is the eicosanoid involved in muscle contractions.

a) Prostaglandin

b) Leukotriene

c) Progesterone

d) Thromboxane

49) Nonsteroidal anti-inflammatory drugs (NSAIDS) block the actions of the COX enzymes

and their production of eicosanoids from ___.

a) steroids

b) arachidonic acid

c) sphingolipids

d) phospholipids

50) The lipid hormones that are derived from arachidonic acid are the ___.

a) arachidonics

b) eicosanoids

c) adrenocorticoid hormones

d) sex hormones