,CHEM 210 Exam 4 | Biochemistry Exam Q&A |
Portage Learning
1. Which of the following best defines a carbohydrate?
A) A polymer of amino acids linked by peptide bonds
B) A polyhydroxy aldehyde or ketone, or a substance that yields these upon hydrolysis
C) A hydrophobic molecule composed of fatty acids and glycerol
D) A nitrogenous base linked to a pentose sugar and phosphate
Correct Answer: A polyhydroxy aldehyde or ketone, or a substance that yields these upon
hydrolysis
Rationale: Carbohydrates are defined as polyhydroxy aldehydes or ketones, or compounds
that yield these upon hydrolysis. This definition encompasses monosaccharides,
disaccharides, and polysaccharides. Amino acid polymers are proteins, and fatty acid esters
are lipids.
2. What is the most abundant organic molecule in the biosphere?
A) Protein
B) Lipid
C) Carbohydrate
D) Nucleic acid
Correct Answer: Carbohydrate
,Rationale: Carbohydrates are the most abundant organic molecules in the biosphere,
largely due to cellulose in plant cell walls. They serve as energy sources and structural
components. Proteins, lipids, and nucleic acids are also essential but less abundant globally.
3. Which functional group is characteristic of carbohydrates?
A) Ester
B) Hydroxyl
C) Thiol
D) Amide
Correct Answer: Hydroxyl
Rationale: Carbohydrates contain multiple hydroxyl (-OH) groups along with either an
aldehyde or ketone group. The hydroxyl groups contribute to their polarity and ability to
form hydrogen bonds. Ester, thiol, and amide groups are not defining features of
carbohydrates.
4. A monosaccharide that contains an aldehyde group is classified as a(n):
A) Ketose
B) Aldose
C) Disaccharide
D) Polysaccharide
Correct Answer: Aldose
, Rationale: An aldose is a monosaccharide that contains an aldehyde group at its terminal
carbon. A ketose contains a ketone group, typically at the second carbon. Disaccharides and
polysaccharides are composed of multiple monosaccharide units.
5. A monosaccharide that contains a ketone group is classified as a(n):
A) Aldose
B) Ketose
C) Anomer
D) Epimer
Correct Answer: Ketose
Rationale: A ketose is a monosaccharide that contains a ketone group, usually at carbon 2.
Fructose is a common example of a ketose. Aldoses contain an aldehyde group, while
anomers and epimers are stereochemical designations.
6. Which of the following is a triose?
A) Glucose
B) Glyceraldehyde
C) Ribose
D) Fructose
Correct Answer: Glyceraldehyde
Portage Learning
1. Which of the following best defines a carbohydrate?
A) A polymer of amino acids linked by peptide bonds
B) A polyhydroxy aldehyde or ketone, or a substance that yields these upon hydrolysis
C) A hydrophobic molecule composed of fatty acids and glycerol
D) A nitrogenous base linked to a pentose sugar and phosphate
Correct Answer: A polyhydroxy aldehyde or ketone, or a substance that yields these upon
hydrolysis
Rationale: Carbohydrates are defined as polyhydroxy aldehydes or ketones, or compounds
that yield these upon hydrolysis. This definition encompasses monosaccharides,
disaccharides, and polysaccharides. Amino acid polymers are proteins, and fatty acid esters
are lipids.
2. What is the most abundant organic molecule in the biosphere?
A) Protein
B) Lipid
C) Carbohydrate
D) Nucleic acid
Correct Answer: Carbohydrate
,Rationale: Carbohydrates are the most abundant organic molecules in the biosphere,
largely due to cellulose in plant cell walls. They serve as energy sources and structural
components. Proteins, lipids, and nucleic acids are also essential but less abundant globally.
3. Which functional group is characteristic of carbohydrates?
A) Ester
B) Hydroxyl
C) Thiol
D) Amide
Correct Answer: Hydroxyl
Rationale: Carbohydrates contain multiple hydroxyl (-OH) groups along with either an
aldehyde or ketone group. The hydroxyl groups contribute to their polarity and ability to
form hydrogen bonds. Ester, thiol, and amide groups are not defining features of
carbohydrates.
4. A monosaccharide that contains an aldehyde group is classified as a(n):
A) Ketose
B) Aldose
C) Disaccharide
D) Polysaccharide
Correct Answer: Aldose
, Rationale: An aldose is a monosaccharide that contains an aldehyde group at its terminal
carbon. A ketose contains a ketone group, typically at the second carbon. Disaccharides and
polysaccharides are composed of multiple monosaccharide units.
5. A monosaccharide that contains a ketone group is classified as a(n):
A) Aldose
B) Ketose
C) Anomer
D) Epimer
Correct Answer: Ketose
Rationale: A ketose is a monosaccharide that contains a ketone group, usually at carbon 2.
Fructose is a common example of a ketose. Aldoses contain an aldehyde group, while
anomers and epimers are stereochemical designations.
6. Which of the following is a triose?
A) Glucose
B) Glyceraldehyde
C) Ribose
D) Fructose
Correct Answer: Glyceraldehyde
