Plant hormones

what are plant hormones?

singalling molecules which respond to environmental changes

What do plan hormones allow the plant to do?

avoid abiotic stress, avoid predators and access resources

What’s the role of auxin?

stimulate cell elongation, leaf loss, maintaining apical dominance

What role does auxin play in leaf loss?

It inhibits it

What’s apical dominance?

When the tip of the stem grows due to high auxin concentration in the tip and stops lower branches growing

What are the roles of gibberellins

stimulates Seed germination, stimulates stem elongation and stimulates stomatal closure

How do gibberellins stimulate seed germination (step 1)?

Water is absorbed by the seed

How do gibberellins stimulate seed germination (step 2)?

embryo produces gibberellins

How do gibberellins stimulate seed germination (step 3)?

gibberellins activates genes for amylases and proteases to be produced

How do gibberellins stimulate seed germination (step 4)?

Anylases and proteases break down food stores into glucose

How do gibberellins stimulate seed germination (step 5)?

Glucose is transported to the embryo which it provides energy for growth

What are the roles of ethene?

stimulates leaf loss and stimulates fruit ripening

What are the differences between plant and animal hormones (4)?

1. plant hormones produced in plant tissues, whereas animal hormones are produced in endocrine glands

2. plant hormones are transported from cell to cell, whereas animal hormones are transported through the blood stream

3. plant hormones acts on most cells, whereas animal hormones only act on specific cells

4. plant hormones have a slower response than animal hormones

What are the commercial uses of ethene?

fruit ripening

What are the commercial uses of auxin?

grow cuttings and as a weedkiller

how do we use auxin to grow cuttings (3 steps)?

1. take a cutting

2. put the cutting in a rooting powder containing auxin

3. plant the cutting

How does auxin work as a weedkiller?

It causes uncontrolled root growth when applied at high concentrations