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Amino acids, proteins and DNA (A-level only)

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Question 13

Which structure represents the predominant species of the amino acid aspartic acid, H2N−CH(CH2COOH)−COOH\text{H}_2\text{N}-\text{CH}(\text{CH}_2\text{COOH})-\text{COOH}H2​N−CH(CH2​COOH)−COOH, in a highly alkaline aqueous solution at pH=12.0\text{pH} = 12.0pH=12.0?

A
H2N−CH−COO−∣CH2−COO− \begin{array}{c} \text{H}_2\text{N} - \text{CH} - \text{COO}^- \\ | \\ \text{CH}_2 - \text{COO}^- \end{array} H2​N−CH−COO−∣CH2​−COO−​
B
H3N+−CH−COO−∣CH2−COO− \begin{array}{c} \text{H}_3\text{N}^+ - \text{CH} - \text{COO}^- \\ | \\ \text{CH}_2 - \text{COO}^- \end{array} H3​N+−CH−COO−∣CH2​−COO−​
C
H3N+−CH−COOH∣CH2−COOH \begin{array}{c} \text{H}_3\text{N}^+ - \text{CH} - \text{COOH} \\ | \\ \text{CH}_2 - \text{COOH} \end{array} H3​N+−CH−COOH∣CH2​−COOH​
D
H2N−CH−COOH∣CH2−COOH \begin{array}{c} \text{H}_2\text{N} - \text{CH} - \text{COOH} \\ | \\ \text{CH}_2 - \text{COOH} \end{array} H2​N−CH−COOH∣CH2​−COOH​
Markscheme

Amino acids, proteins and DNA (A-level only) Questions

  1. A Level
  2. /Chemistry
  3. /Amino acids, proteins and DNA (A-level only)

30 exam-style questions on AQA A Level Chemistry Amino acids, proteins and DNA (A-level only), covering Amino acids (A-level only), Proteins (A-level only), Enzymes (A-level only), DNA (A-level only), and Action of anticancer drugs (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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