(a) Gibberellin is a plant hormone that has an important role in seed germination. [Figure 6.1] is a diagram of a section through a barley seed (grain). On [Figure 6.1]: • Draw one arrow, labelled G, to show the movement of gibberellin during germination. • Draw one arrow, labelled A, to show the movement of amylase during germination.

Mark scheme

Marking points from the official mark scheme (May/June 2022). The mark or mark type is shown in brackets.

1. [2] G – embryo to aleurone layer; A – aleurone layer to endosperm ;
2. [3] any three from: 1 hydrolyses / breaks down / digests / converts, starch / amylose ; 2 in endosperm ; 3 to, maltose / glucose ; 4 (glucose) used by embryo ; 5 (glucose used) for, respiration / growth;
3. [4] any four from: accept distilled water for A, 500mg dm-³ for B and 1000mg dm-³ for C. 1 seeds of B and C germinated before seeds of A or seeds soaked in gibberellin germinated before seeds soaked in distilled water ; ora 2 rate of (increase in percentage) germination was, highest in C or higher in C than, B/A or higher as the concentration of gibberellin increases ; ora 3 final / day 10 / maximum (percentage) germination was, highest in C or higher in C than, B/A or higher as the concentration of gibberellin increases ; ora 4 data quote between two groups; mp1 - A by day 6 and B and C by day 2 mp1 - A germinates four days after B and C ora mp2 – A – 2.2 В – 5.2 С – 9.2, percentage germination day-1 mp3 - A - 22% В – 52% С – 92% mp3 - A to C = 70% more, A to B = 30% more, B to C = 40% more 5 percentage germination in C levels off after 9 days ; 6 AVP; e.g. no seeds germinate by day 1