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AP®BiologyCollege BoardExam QuestionsUnit 1: Chemistry of LifeBiological Macromolecules

Biological Macromolecules (College Board AP® Biology): Exam Questions

13 mins13 questions
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1
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Which of the following statements correctly describes dehydration synthesis?

  • The addition of water in order to allow the formation of a polymer.

  • The process by which the bonds between monomers are broken.

  • The process by which two monomers join together with a hydrogen bond.

  • The process by which two monomers join together with a covalent bond.

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21 mark

DNA and RNA are made up of a repeating unit bonded together via strong covalent bonds.

Which of the following is the correct term to describe DNA or RNA?

  • Polymer of bases

  • Polymer of nucleotides

  • Monomer of bases

  • Monomer of nucleotides

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3
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Proteins are essential macromolecules in living cells.

Which of the following statements about proteins is correct?

  • A protein's structure is determined by the types of amino acid present within its structure.

  • Quaternary structure in proteins comes about due to interactions between multiple polypeptide chains.

  • The amino acids in a protein are connected by ionic bonds known as peptide bonds.

  • The secondary structure of a protein is its overall three-dimensional shape.

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4
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Lipids are macromolecules which contain carbon, hydrogen and oxygen atoms. Figure 1 below shows representations of two lipid molecules.

Two molecular structures: Molecule 1 has three hydrocarbon chains. Molecule 2 features a phosphate head and two hydrocarbon chains.
Figure 1. Two lipid molecules

Which of the following statements about the lipids in Figure 1 is correct?

  • Molecule 2 has a polar region and molecule 1 does not.

  • The fatty acids of the two lipids will have the same functional properties.

  • Molecule 2 is hydrophilic.

  • Molecule 1 is hydrophilic.

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1
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Proteins play a key role in many biological functions. Insulin is a protein hormone that regulates blood sugar levels. Insulin is composed of chains of amino acids which are linked together by covalent bonds during its synthesis in the pancreas.

Which of the following describes the bonds that connect the monomers in insulin?

  • Monomers in insulin are connected by a peptide bond between the carboxyl ends of two amino acids.

  • Monomers in insulin are connected by a peptide bond between the carboxyl end of one amino acid and the amino group of a neighboring amino acid.

  • Monomers in insulin are connected via a peptide bond between the amino groups of two amino acids.

  • Monomers in insulin are connected via a peptide bond between the R group of one amino acid and the amino group of a neighboring amino acid.

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2
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Researchers produced a particular type of reactive molecule, known as a radical, that can interact with a protein's amino acids at a molecular level. Under certain conditions the radical molecules selectively react to break carbon-carbon bonds within an amino acid, meaning that protein editing can be achieved.

Which of the following best predicts the location at which radicals interact with proteins?

  • Radicals interact with the peptide bond of an amino acid.

  • Radicals interact with the region where the carboxyl group attaches to the rest of the amino acid.

  • Radicals interact with the region where the amino group attaches to the rest of the amino acid.

  • Radicals interact with the peptide bond of a di-peptide.

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3
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A key structural component of plant cell walls is cellulose. Bonds within cellulose allow cellulose fibers to provide rigidity and support to plant cells.

Which of the following identifies the bonds formed between monomer units during the formation of cellulose?

  • Hydrogen bonds

  • C-C covalent bonds

  • Peptide bond

  • Disulphide bridge

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41 mark

DNA and RNA molecules have structural similarities and differences related to their function.

Which of the following best describes the differences between DNA and RNA?

  • Both DNA and RNA have three components; a sugar, a phosphate group and a nitrogenous base. DNA contains deoxyribose and RNA contains ribose. RNA contains uracil and DNA contains thymine. DNA is usually single stranded while RNA is usually double stranded. The two DNA strands in double-stranded DNA are antiparallel in directionality.

  • Both DNA and RNA have two components; a sugar and a nitrogenous base. DNA contains deoxyribose and RNA contains ribose. RNA contains uracil and DNA contains thymine. DNA is usually single stranded; RNA is usually double stranded. The two DNA strands in double-stranded DNA are antiparallel in directionality.

  • Both DNA and RNA have three components; a sugar, a phosphate group and a nitrogenous base. DNA contains deoxyribose and RNA contains ribose. RNA contains uracil and DNA contains thymine. DNA is usually double stranded and RNA is usually single stranded. The two DNA strands in double-stranded DNA are antiparallel in directionality.

  • Both DNA and RNA have three components; a sugar, a phosphate group and a nitrogenous base. DNA contains oxyribose and RNA contains ribose. RNA contains uracil and DNA contains thymine. DNA is usually single stranded and RNA is usually double stranded. The two DNA strands in double-stranded DNA are antiparallel in directionality.

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51 mark

RNA and DNA are comprised of monomers called nucleotides. Nucleotides are made up of three different structures.

Which of the following correctly shows the structure of a nucleotide?

  • Chemical structure of adenine nucleotide showing a phosphate group, ribose sugar, and adenine base. Phosphate is circled and connected to ribose.
  • Chemical structure of adenosine monophosphate, featuring a nucleotide with a phosphate group, ribose sugar, and adenine base.
  • Chemical structure of adenosine monophosphate, showing adenine ring linked to a ribose sugar and phosphate group.
  • Chemical structure of adenine nucleotide, showing a phosphate group, ribose sugar, and adenine base with atomic bonds and labels.

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1
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Amino acids are used to make proteins. Table 1 shows the R groups of six different amino acids.

Amino acid

R group

Alanine

CH3

Asparagine

CH2CONH2

Aspartic acid

CH2COOH

Glutamic acid

CH2CH2COOH

Glycine

H

Serine

CH2OH

Which of the following three amino acids are used to make the polypeptide shown in Figure 1?

Structural formula of a polypeptide showing three amino acids linked by a peptide bond with functional groups including NH2, OH, and COOH.
Figure 1. The structural formula of a polypeptide

  • Serine, alanine and aspartic acid.

  • Glutamic acid, alanine and asparagine.

  • Aspartic acid, glycine and serine.

  • Serine, asparagine and alanine.

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2
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A microbiologist studied phospholipid composition in the membranes of bacteria. The table below shows the percentage of saturated and unsaturated fatty acids in the phospholipid bilayers of three different bacterial samples.

Bacteria sample

Environment from which sample was collected

% saturated fatty acids

% unsaturated fatty acids

A

Hot springs at 80 °C

82

18

B

Arctic waters at -2 °C

25

75

C

Human small intestine at 37 °C

55

45

Which of the following conclusions is best supported by the data?

  • All bacteria in the human body have an approximately equal mix of saturated and unsaturated fatty acids in their plasma membranes.

  • There is a percentage increase of 317 % in the number of unsaturated fatty acids between the membranes of the bacteria in sample A and sample B.

  • Having more saturated fatty acids in the phospholipids of a membrane decreases membrane fluidity.

  • Cell membrane phospholipids contain more saturated fatty acids than unsaturated fatty acids.

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3
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The more denatured a protein is, the less stable the molecule becomes. The denaturation of three different proteins (P, Q and R) at different temperatures was investigated. The following graph shows the results of this investigation.

Graph showing percentage of unfolded molecules against temperature in °C. Curves P, Q, R demonstrate unfolding transitions at different temperatures.
Figure 1. Effect of temperature on percentage of unfolded proteins.

Which of the following would be a valid conclusion from these results?

  • Protein R is less stable and has a lower rate of denaturation above 70 °C compared to protein Q, while protein P is fully denatured by 80 °C.

  • Protein R is more stable and has a lower rate of denaturation above 70 °C compared to protein Q, while protein P is the least heat tolerant of all the proteins.

  • Protein R is more stable and has a lower rate of denaturation below 70 °C compared to protein Q, while protein P is fully denatured by 80 °C.

  • Protein Q is less stable and has a higher rate of denaturation below 70°C compared to protein R, while protein P is the least heat tolerant of all the proteins.

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4
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A molecular biologist isolated double-stranded DNA (dsDNA) and folded, single-stranded RNA (ssRNA) from different cell types and measured the percentage of cytosine (C) and guanine (G) bases in each sample. They then carried out a study to establish the temperature at which half of the nucleic acid strands separate, or unfold, due to hydrogen bond disruption (Tm).

The results are below:

Sample

Type of nucleic acid

% C + G content

Tm (°C)

A

dsDNA

42

82

B

dsDNA

58

94

C

ssRNA

39

67

D

ssRNA

55

74

Which of the following statements relating to the data in the table is correct?

  • ssRNA is more thermally stable than dsDNA.

  • A-T base pairs form stronger hydrogen bonds than G-C pairs.

  • The result for sample C is likely to be anomalous for this dataset.

  • Sample D has an adenine content of 22.5 %.

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