Ripe strawberries contain the flavylium cation, an anthocyanin. By referring to table 22 of the data booklet, explain why ripe strawberries are red.

Outline the difference in solubility in water between anthocyanins and carotenes, by referring to their structures in table 22 of the data booklet.

Outline another convention used for specifying a molecule’s spatial configuration and its relationship with the (\( + \)) and (\( - \)) notation (previously referred to as \(d\) and \(l\)).

red light/radiation transmitted;

Accept “red light/radiation reflected”.

green light/radiation absorbed / green is complementary colour / complementary colour absorbed;

“Light/radiation” only needs to be mentioned once in either M1 or M2.

Award [1 max] for “red transmitted and green absorbed”.

(as) electrons promoted into higher energy levels;

(in visible region due to extensive) conjugation / alternate single and double (carbon–carbon) bonds / involves delocalization (of \(\pi \) electrons);

anthocyanins are (water) soluble but carotenes are insoluble;

anthocyanins have hydroxyl/OH/polar groups (so are water soluble) / anthocyanins can form hydrogen bonds with water / carotenes have no hydroxyl/OH/polar groups/are non-polar (so not water soluble) / carotenes do not form hydrogen bonds with water / carotenes have long hydrophobic parts / OWTTE;

Accept “alcohol or hydroxy” for hydroxyl but not hydroxide.

D/L used for carbohydrates and amino acids / D/L uses glyceraldehyde as a reference;

Accept Fischer-Rosanoff/Rosanoff (convention) for carbohydrates and amino acids.

Do not accept just “CORN rule used for amino acids”.

no relationship / OWTTE;

The same general comments apply here in part (a) as in Q4 in Option A. In (b), some excellent answers were seen and differences in polarity and solubility were correctly outlined. Many students seemed to have an outline understanding of the CIP convention, though many lacked the language skills to communicate their knowledge succinctly. The ordering of groups by atomic mass rather than atomic number seemed a common misapprehension and many referred incorrectly to molecular mass. In (d), few managed to score both marks. D/L and d/l were often mixed up and few realized that there is actually no relationship between the (\( + \)) and (\( - \)) and D/L conventions.

The same general comments apply here in part (a) as in Q4 in Option A. In (b), some excellent answers were seen and differences in polarity and solubility were correctly outlined. Many students seemed to have an outline understanding of the CIP convention, though many lacked the language skills to communicate their knowledge succinctly. The ordering of groups by atomic mass rather than atomic number seemed a common misapprehension and many referred incorrectly to molecular mass. In (d), few managed to score both marks. D/L and d/l were often mixed up and few realized that there is actually no relationship between the (\( + \)) and (\( - \)) and D/L conventions.

The same general comments apply here in part (a) as in Q4 in Option A. In (b), some excellent answers were seen and differences in polarity and solubility were correctly outlined. Many students seemed to have an outline understanding of the CIP convention, though many lacked the language skills to communicate their knowledge succinctly. The ordering of groups by atomic mass rather than atomic number seemed a common misapprehension and many referred incorrectly to molecular mass. In (d), few managed to score both marks. D/L and d/l were often mixed up and few realized that there is actually no relationship between the (\( + \)) and (\( - \)) and D/L conventions.