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

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Question 11

Lysine (2,6-diaminohexanoic acid) has the structure H2N−CH(COOH)−(CH2)4NH2\text{H}_2\text{N}-\text{CH}(\text{COOH})-(\text{CH}_2)_4\text{NH}_2H2​N−CH(COOH)−(CH2​)4​NH2​. Which is the main organic species present in an aqueous solution of lysine at pH=13\text{pH} = 13pH=13?

A

H3N+−CH(COOH)−(CH2)4NH3+\text{H}_3\text{N}^+-\text{CH}(\text{COOH})-(\text{CH}_2)_4\text{NH}_3^+H3​N+−CH(COOH)−(CH2​)4​NH3+​

B

H3N+−CH(COO−)−(CH2)4NH3+\text{H}_3\text{N}^+-\text{CH}(\text{COO}^-)-(\text{CH}_2)_4\text{NH}_3^+H3​N+−CH(COO−)−(CH2​)4​NH3+​

C

H2N−CH(COO−)−(CH2)4NH2\text{H}_2\text{N}-\text{CH}(\text{COO}^-)-(\text{CH}_2)_4\text{NH}_2H2​N−CH(COO−)−(CH2​)4​NH2​

D

H3N+−CH(COO−)−(CH2)4NH2\text{H}_3\text{N}^+-\text{CH}(\text{COO}^-)-(\text{CH}_2)_4\text{NH}_2H3​N+−CH(COO−)−(CH2​)4​NH2​

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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