Plant Hormone s

Notes prepared by: N Ngabaza
Life sciences tutor: 068 341 2728
PLANT RESPONSE TO ENVIRONMENT ( PLANT HORMONES)


A hormone is an oganic substance produced in small amounts in one part of the body
then transported to other parts of the body for growth and development,.

There are THREE different types of plant hormones namely:

1. Auxins
2. Gibberelins
3. Abscicic acid

AUXINS

The auxins bring about the bending effect of plants known as tropism. When the stem
bends towards light, it is known as phototropism, and when the roots bend
downwards, it is known as geotropism...

FUNCTIONS

1. Responsible for apical dominance ( that promotes growth of vertical
and lateral branches )
2. Responsible for cell division
3. Promotes root development
4. Promotes cell division by mitosis




DIAGRAM SHOWING A PLUMULE AND RADICLE AFTER SEEDLING

, GIBBERELINS Notes prepared by: N Ngabaza
Life sciences tutor: 068 341 2728


FUNCTIONS

1. Increases fruit size

2. Bring about elongation of the
internodes of the stem.

3. Stimulates root growth

4. Helps with germination of seeds

5. Promotes sprouting of seeds that
have been dormant

6. Promotes development of flowers



ABSCICIC ACID




FUNCTIONS


1. Brings about seed dormancy by
slowing down germination

2. Promotes aging of leaves

3. Promotes flowering in plants

4. Helps close the stomata to prevent
water loss, especially during the period
of drought