Zadanie 6b
Wzorowane na: Chemistry HL Paper 3, November 2023, TZ2, pytanie 6(b). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Polecenie
A biochemist wants to find out which of the amino acids glycine, serine and leucine are present in a short peptide.
Outline how paper chromatography can be used to do this.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
Any three of:
hydrolyse the peptide «to its amino acids, e.g. by heating with hydrochloric acid» ✔
place spots of the hydrolysate and of the three known amino acids on a baseline on the paper/stationary phase AND let the solvent rise up the sheet ✔
amino acids separate because they have different attractions to the mobile phase and the stationary phase/different solubilities ✔
make the spots visible with a locating agent/ninhydrin
OR
view under ultraviolet/UV light ✔
calculate Rf values AND compare them with the known amino acids ✔
Schemat punktowania
Award [1] for each correct marking point, maximum [3]. The last point needs Rf to be named. Separation by electrophoresis earns nothing. Use of a locating agent is not required by the 2023 guide, so the other four points can already give the full [3].