How do plants move

Plants - movement and irritability of plants


Movement and irritability of plants

Forms of movement:
Plants can move just like animals or humans, only at a much slower speed because they don't have muscles. There are different types of movement:

  1. Growth movement: When a plant grows stronger on one side, it curves in the direction.
  2. Turgor movement: When the internal pressure of the cell (turgor) decreases, there is a decrease in volume, when it increases, it increases. This can be done quickly because cells in their organ joints are mobile.
    Example: The climbing mechanism of many climbing cucurbits: In order to find support, the surroundings are scanned with a gripping thread that circles clockwise. If the thread has found a hold, it immediately begins to wrap around it. If the attachment is successful, the thread winds up like a telephone receiver cord. (Book p.108 Fig.1)
  3. Plasma movement: cytoplasm flows in the cell or along the cell surface. It is believed that this movement is caused by proteins, like in an animal cell. (Book p.109 fig.4)

Stimuli to which plants respond:
These are light, gravity, temperature, contact stimuli and chemical substances. Travel response options:

  1. Tropisms: Are movements of stationary plants that are related to the direction of the stimulus.
    • With light: It is called phototropism; the shoot of a plant is positive phototropic, that is, it grows towards the light. The root, on the other hand, is negative, which means it grows away from the light. (Book p.109 fig.5)
    • With gravity: Trees grow vertically on a slope, this is due to starch grains that absorb the gravitational stimuli.
    • With chemical substances: A fungal thread grows towards a sugar solution.
  2. Nastia: movement of plant organs caused by external influences. The direction depends on the structure of the organ.
    • In the light: dandelion opens its flower head. (through turgor joints)
    • In case of temperature fluctuations: Snowdrops behave like dandelions in light. (Book p.109 fig.6)
    • When touched: The leaves of the Venus flytrap close.
  3. Taxia: local movement of freely moving organisms, depending on the direction of the stimulus. The flagellum Euglena swims, for example: Towards a light source.
    The saying "react like a mimosa" has a biological background. In order to protect itself from grazing animals, this plant has developed the following mechanism: With the slightest touch, its leaves sink, with strong touch even their petioles. Then they are protected by the stem provided with thorns. The process also provides protection from rainfall. The speed at which the plant moves is 4-30 mm / s. Plant clearly grows towards light.

Growth substances:
The so-called "plant hormones" are organic substances that are transported in the plant's conduit system and are used to regulate growth. There are the following groups

  1. Auxins: mainly promotes stretch growth. The most important auxin indole-3-acetic acid (IES) causes unfertilized fruits to grow when sprayed.
  2. Gibbarelline: This is the name of around 50 substances that promote length growth. They are mainly found in immature seeds and buds. When brewing beer, they are used to stimulate the germination of dormant barley grains.
  3. Cytokinins: They promote cell division, delay the aging process and cause buds to sprout, seed germination and root growth.
  4. Abscisic acid: is a "growth brake". It promotes leaf fall, the ripening of fruits and the dormancy of the buds.
  5. Ethene: is a gaseous hydrocarbon and promotes the aging and ripening of the fruit. It is used to ripen green harvested fruits.
    The growth substances are used to control weeds. Since they are absorbed through the leaves, the grain with the narrow leaves is encouraged to grow while weeds, with the large leaves, "grow to death".


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