Chapter 33: Plant Responses Objectives. Explain the term: growth regulation. Define the following terms: tropisms, phototropism, geotropism, thigmotropism, hydrotropism, chemotropism. Name examples of phototropism & geotropism. Define the term: growth regulator.
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Chapter 33: Plant Responses
Explain the term: growth regulation.
Define the following terms: tropisms, phototropism, geotropism, thigmotropism, hydrotropism, chemotropism.
Name examples of phototropism & geotropism.
Define the term: growth regulator.
Outline the transport of regulators via the vascular system.
Explain the term: Combined Effect
Explain the term: Growth Promoter.
Explain the term: Growth Inhibitor
Name 4 methods of anatomical/chemical adaptations that protect plants.
State 2 examples of the use of plant regulators.
Mandatory Activity :Effects of I.A.A. Growth Regulators on Plants
A stimulus is anything that causes a response in an organism,
or in any of its parts.
A response is the activity of a cell or organism to a stimulus.
Plant responses involve growth and changes in growth due to a stimulus
Plant adapt to new situations by
modifying their growth, by means of
chemicals called growth regulators [hormones].
Growth is the increase in the number, size and volume of cells.
New roots developing
Growth shut down for winter
Plant growth regulators
promote cell enlargement and growth,
are involvedin phototropism and apical dominance
Quicker growth here due to more hormones
In shoots, light causes auxin to move down the shaded part of the stem, causing the shoot to grow towards the sunlight. This is called PHOTOTROPISM.
Artificial auxins can also be used to kill weeds, stimulate root formation in cuttings, …
Uses of plant regulators
Some adaptations that plants use to protect themselves include:
They protect themselves against:
Plants can adapt themselves for protection in two ways:
Plants can grow and regenerate throughout their life.
They can produce new roots, stems, leaves.
To investigate the effect of IAA concentration on plant tissues.
1. Different concentrations of IAA are prepared.
2. Seeds are grown in petridishes with different
concentrations of IAA.
3. Changes in length of seedlings shoots and roots are recorded.
At low concentrations the roots grow larger and
shoots stay short.
At higher concentrations the shoots grow larger and
roots stay short.