AP®BiologyCollege BoardExam QuestionsUnit 1: Chemistry of LifeBiological Macromolecules

Biological Macromolecules (College Board AP® Biology)

Exam Questions

5 mins5 questions
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 through specific covalent bonds during its synthesis in the pancreas. Which of the following represents the type of bonds that connect the monomers in insulin?

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

  • Monomers in insulin are connected via a peptide bond between the carboxylic group 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 group 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 of where the radicle interacts?

  • Radicles interact with the peptide bond of an amino acid

  • Radicles interact with the R-group of an amino acid

  • Radicles interact with the amino group of an amino acid

  • Radicles interact with the peptide bond of a di-peptide

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3
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In the study of plant biology, a key structural component of plant cell walls is cellulose. Specific bonds within cellulose allow the cellulose fibers to provide rigidity and support to plant cells. Which of the following best describes 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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4
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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, aspartic acid

  • Glutamic acid, alanine, asparagine

  • Aspartic acid, glycine, serine

  • Serine, asparagine, alanine,

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5
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The denaturation of three different proteins (P, Q and R) at different temperatures were investigated. The more denatured a protein is, the less stable the molecule becomes. 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 the most valid conclusion that the scientists can draw from these results?

  • Protein R would be less stable and had a lower rate of denaturation above 70°C compared to protein Q, while protein P was fully denatured by 80°C

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

  • Protein Q would be more stable and had a lower rate of denaturation below 70°C compared to protein R, while protein P was fully denatured by 80°C

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

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