Test: Chemical Coordination In Plants - UPSC

Option ( c) is correct as touch me not leaves not results in change in water content to response to stimuli so it is not related to growth in any aspect. 

Nastic movements are plant movements that occur in response to environmental stimuli but unlike tropic movements, the direction of the response is not dependent on the direction of stimulus.  Some examples of Nastic movements include the closing of the carnivorous Venus flytrap leaf when it captures prey or the folding of the mimosa leaf when it is disturbed.

Hormones synthesized at places away from where they act. Growth is seedling germination. Chemotropic is the growth of pollen tubes towards ovules. Root is positively geotrophic. Shoot is positively phototropic.

Auxin, cytokinin and gibberellins are growth promoting plant hormones while Abscisic acid is the growth inhibitior plant hormone.

The movement of a plant part in response to an external stimulus in which the direction of response is not determined by the direction of stimulus is known as nastic movement.

Plants have no brain or central nervous system, which means they can't feel anything.

Humans and animals perceive pain through sensory nerve cells. These are the same type of cells that transmit information from our senses, allowing us to smell, see, hear, taste, and touch. These cells are part of what’s called the peripheral nervous system, which includes all the body's nerves except those in the spinal cord and brain.

Peripheral nerve cells form a network that carries messages from the skin, muscles, and organs to the spinal cord and brain. The brain responds by sending back messages to the pain site that promote the healing process.

Even though plants don’t have nervous systems, they can respond to stimuli. For example, when an aphid attacks a leaf, this sends an electrical signal that goes from leaf to leaf to tell the plant to start protecting itself. But it’s important to note that responding to damage does not mean the plant is in pain.

Auxins and gibberellins help promote plant growth, particularly in stem elongation. Cytokinins promote cell division and are produced in growing areas of plants. Abscisic acid plays a role in cell dormancy and is involved in the opening and closing of the stomata on leaves. Finally, ethylene is a gas that is produced by ripening fruits.

 Movement in a sensitive plant 

(i) It occurs in response to an external stimulus like touch and shock.

(ii) Plant cells change shape by changing the amount of water.

(iii) No nerves are involved.

(iv) There is no specialized tissue in plants for conduction of information.

(v) Plant cells do not have specialized proteins.

The movement of a plant subjected to constant directional pressure is called thigmotropism, from the Greek words thigma meaning “touch,” and tropism implying “direction.” Tendrils are one example of this. The meristematic region of tendrils is very touch sensitive; light touch will evoke a quick coiling response. Cells in contact with a support surface contract, whereas cells on the opposite side of the support expand. Application of jasmonic acid is sufficient to trigger tendril coiling without a mechanical stimulus.

The growth of pollen tubes towards ovules is due to chemotropism. Chemo-tropism is growth of organisms such as bacteria and plants, navigated by chemical stimuli from outside of the organism or organism's part.