1. apical
Cytokinin
mitosis
leaf node
Auxin
cell elongation

2. gibberellin
elongation
of internodal regions

3. Apical meristem Zone of elongation Leaf node Internodal region
Tip of root or shoot where cell division occurs
cytokinin
Zone of elongation
Area behind the apical meristem where cells enlarge
auxin
Leaf node
Area on stem from which a lateral leaf grows
Internodal region
Length affected
by gibberellin
node
Internodal region
Area of the stem between leaf nodes
gibberellin

4. promotes cell division
at the meristems
cytokinins

5. causes cells elongation
AUXIN
Small new cell
from mitosis
Large elongated cell
causes cells elongation
in zone of elongation
auxin

6. stem elongation
gibberellin

7. Summary table page 39 CCEA A2 text QUESTION 3 PAGE 45

16. Light is perceived by the tip of the coleoptile.
darwin
The coleoptile is positively phototropic. It bends towards the light by unequal elongation of the region just behind the tip.
Light is perceived by the tip of the coleoptile.

17. boysen - jensen
Mica prevents movement of auxin from the tip to the shaded side of the coleoptile.

18. Auxin diffused into the agar block.
went
Auxin diffused into the agar block.
Auxin from the block diffused down one side of the shoot, causing cells to elongate and the shoot to bend.
Auxin is produced in the tip but the cells behind the tip respond to its affect.
Tip on gelatine block exposed to light. Tip replaced by off centre block and placed in dark.
Shoot grew bent

20. PHYTOCHROME: controls flowering
RED light
in daylight
P660
P730
FAR RED light
Slow conversion
in dark

21. short
day plants

22. long
day plants