A commercial grower wants to optimize crop production. What are two commercial uses of gibberellins? Tick ($✓$) two boxes.

• To control the ripening of fruit during transport
• To stimulate root growth in cuttings
• To end seed dormancy and initiate germination
• To kill weeds selectively
• To promote flowering in off-season crops

Students investigated the effect of light on the direction of shoot growth in oat seedlings (coleoptiles). Figure 1 shows the experimental setup.

Draw on this

Describe two improvements the students should make to their investigation.

Figure 2 shows a seedling shoot bending towards a light source on the left.

Suggest how the students could accurately measure the length of the curved shoot in Figure 2.

Explain how the unequal distribution of auxin causes the shoot in Figure 2 to bend towards the light source. Refer to Side X (illuminated side) and Side Y (shaded side) in your answer.