Question 1

A research team tracked the carbon atoms in glucose molecules to see where they ended up when the glucose was taken up and metabolized by human cells grown in culture.The team found that 9 percent of the carbon atoms ended up in proteins.This result provides evidence for which biological function of carbohydrates in living organisms?

Accepted Answer

A)  Energy storage 
B)  Energy source 
C)  Energy transport 
D)  Carbon skeleton source 
E)  Structural support

Question 2

Refer to the figure below showing the three different oligosaccharides present on the surfaces of human red blood cells that determine blood type.  Antibodies are proteins produced in the body in response to foreign substances.Antibodies recognize and bind to these foreign substances to remove them from the body.How would blood cells containing the oligosaccharide type O be received if they were transfused into the body of a patient whose own blood cells contained the oligosaccharide type A? Would the reaction be different if the reverse situation occurred; that is, blood cells containing the oligosaccharide type A transfused into a patient whose blood cells contained oligosaccharide type O? Describe the role of the oligosaccharides in these two situations.

Accepted Answer

The answer of Refer to the figure below showing the...

Question 3

Based on its structure, a triglyceride is most closely related to a

Accepted Answer

A)  wax. 
B)  phospholipid. 
C)  fat-soluble vitamin. 
D)  steroid. 
E)  carotenoid.

Question 4

Sketch and label a triglyceride and a phospholipid.Write a brief comparison of the two structures.

Accepted Answer

The answer of Sketch and label a triglyceride and a...

Question 5

Unsaturated fatty acids do not pack together because of the _______ in their hydrocarbon chains.

Accepted Answer

A)  double bonds 
B)  glycosidic linkages 
C)  peptide bonds 
D)  disulfide bridges 
E)  van der Waals forces

Question 6

Draw a diagram of a phospholipid bilayer, and identify the hydrophobic tails and the hydrophilic heads.Where in the cell can you find such a structure?

Accepted Answer

The answer of Draw a diagram of a phospholipid bilayer,...

Question 7

Comparing two fatlike solid substances, you determine that sample A has a higher melting point than sample B.Sample A, therefore,

Accepted Answer

A)  has a higher number of carbon-carbon double bonds. 
B)  has a lower number of carbon-carbon double bonds. 
C)  is a saturated fat, and sample B is an unsaturated fat. 
D)  is an unsaturated fat, and sample B is a saturated fat. 
E)  is a triglyceride, and sample B is a simple lipid.

Question 8

Refer to the figure showing the tertiary structure of a section of a mouse protein, and the table below, showing changes to the stability of the protein for specific single amino acid substitutions.   The numbers shown in the left column refer to the amino acid's position in the polypeptide chain.Which conclusion is consistent with these data?

Accepted Answer

A)  Large changes in sizes of amino acid side chains disrupt the tertiary structure in this region of the protein. 
B)  The tertiary structure of this section of the protein is stabilized by salt bridges between amino acid residues. 
C)  Disruption of hydrophobic interactions in this section of the protein leads to decreased stability of its tertiary structure. 
D)  Protein stability does not change no matter what amino acid is inserted at certain positions in the polypeptide chain. 
E)  Protein stability always decreases whenever any amino acid change is made at certain positions in the polypeptide chain.

Question 9

A student claims that all triglycerides have the exact same properties, since they are all composed of the same units: a glycerol molecule and three fatty acids.Which statement provides the best response to this claim?

Accepted Answer

A)  The claim is correct because all triglycerides have the same pattern of ester linkages between fatty acids and glycerol. 
B)  The claim is correct because all fatty acid tails consist of long hydrocarbon tails that contribute to the nonpolar nature of triglycerides as a class. 
C)  The claim is incorrect because triglycerides can assume different shapes due to random motion of their hydrocarbon chains. 
D)  The claim is incorrect because the hydrocarbon chains of triglycerides vary in length and number of double bonds. 
E)  The claim is incorrect because triglycerides are found in many different types of organisms.

Question 10

Refer to the figure below.  The molecules in the figure are

Accepted Answer

A)  structural isomers. 
B)  optical isomers. 
C)  hydrophobic. 
D)  monosaccharides. 
E)  fatty acids.

Question 11

The monomers that make up polymeric carbohydrates like starch are called

Accepted Answer

A)  nucleotides. 
B)  trisaccharides. 
C)  monosaccharides. 
D)  nucleosides. 
E)  fatty acids.

Question 12

Refer to the ribbon model of a section of polypeptide backbone in a protein.  The two examples of secondary structure shown in the figure are a F1F1F1S1F1F1F10 pleated sheet at point A and _______ at point B.

Accepted Answer

The answer of Refer to the ribbon model of a...

Question 13

Lipids are able to perform all of the following functions except

Accepted Answer

A)  be a signal from one part of the body to the other. 
B)  color the leaves of a tree. 
C)  prevent feathers from getting wet. 
D)  store energy. 
E)  dissolve polar substances.

Question 14

All carbohydrates

Accepted Answer

A)  are polymers. 
B)  are simple sugars. 
C)  are found in biological membranes. 
D)  have the general structure (C1H2O1)n or CnH2nOn. 
E)  are more soluble in nonpolar solvents than in water.

Question 15

The amino acid sequence of a protein isolated from human blood cells is the same as the amino acid sequence of a protein isolated from chimpanzees.Which statement related to this observation is accurate?

Accepted Answer

A)  Humans and chimpanzees are so closely related that all of their protein sequences are identical. 
B)  The two proteins serve the same function in both humans and chimpanzees because their structures are the same. 
C)  The folding is likely to differ in the polypeptide chains in the two cases because they exist in cells of different organisms. 
D)  The two proteins will have the same properties, since they have the same primary structure, but different functions, since they come from different species. 
E)  The biological properties of the two proteins must differ, since they were isolated from two different species.

Question 16

Suppose you want to construct a protein that is 50 amino acids long.What is the theoretical number of different proteins you could make?

Accepted Answer

A)  1050 
B)  2050 
C)  20 × 50 
D)  5020 
E)  50 × 50

Question 17

Complex carbohydrates are a mainstay of many diets.What are some properties that make them excellent food sources?

Accepted Answer

The answer of Complex carbohydrates are a mainstay of many...

Question 18

Refer to the figure below.  Suppose you had to synthesize a phospholipid using the compound shown above as starting material.What step would you take?

Accepted Answer

A)  Add a phosphate group onto one of the carbons of the glycerol backbone. 
B)  Add a phosphate group onto the end of one of the hydrocarbon tails. 
C)  Add a phosphate group onto the carbonyl carbon connecting one of the fatty acids to the glycerol backbone. 
D)  Replace one of the fatty acids bonded to the glycerol backbone with a phosphate group. 
E)  Replace one of the glycerol backbone carbons with a phosphate group.

Question 19

A scientist isolates a previously undiscovered protein from a fruit fly and determines the sequence of amino acids making up the protein.Upon comparing the sequence to a database, he finds another protein isolated from a lizard with the same sequence.The lizard protein is known to be involved in glucose metabolism.The scientist predicts that the fruit fly protein must also be involved in glucose metabolism.How can his prediction be justified?

Accepted Answer

A)  Two proteins isolated from modern terrestrial animals such as fruit flies and lizards should be closely related, which implies that the two molecules will function in the same way. 
B)  Two proteins with the same distribution of amino acids have the same size, which allows the two molecules to function in the same way. 
C)  Two proteins made up of the same number and types of amino acids have the same composition, which allows the two molecules to function in the same way. 
D)  Two proteins with the same amino acid composition have the same mass, which allows the two molecules to function in the same way. 
E)  Two proteins with the same amino acid sequence have the same structure, which allows the two molecules to function in the same way.

Question 20

Refer to the table below.  Based on information provided in the table, these disaccharides have different _______.

Accepted Answer

The answer of Refer to the table below.  Based...

Exam 3: Proteins, Carbohydrates, and Lipids