One of the characteristics of the living organism, as it occurs in all the living organisms, starting with the unicellular organisms til reaching the human to maintain its life
Sensitivity in plants is less obvious than in animals, and sensitivity in human reaches the highest degree of efficiency and accuracy
Sensitivity (Irritability)
The response of living organism to the internal and external stimuli with a suitable response to maintain its life
Sensitivity in plants
Response of plant to touch and darkness
Tropism
Response of plant to touch and darkness
Obvious through observation of Mimosa plant leaflets
Leaves are compound and pinnate
Each leaf has a primary rachis, which carries 4 secondary rachises at its end
Each secondary rachis carries two rows of leaflets
At the base of each primary and secondary rachises and leaflet, there is a swollen structure called a pulvinus
Response of Mimosa plant leaflets to touch
1. Leaflets soon droop as if they have wilted
2. Other neighboring leaflets soon follow and droop
3. Effect is seen in all the leaflets, and the leaf petiole droops at the end
Response of Mimosa plant leaflets to darkness
1. In daytime, the leaflets are held in a horizontal position (wake movement)
2. At night, the leaflets hang downwards and fold their upper surfaces (sleep movement)
Plant tropisms
Phototropism (response to light)
Geotropism (response to gravity)
Thigmotropism (response to touch)
Hydrotropism (response to water)
Phototropism
Curvature of stem or root of a plant in response to unequal exposure to light
Stem moves towards the light and root moves away from it
The root hair cells are the main site of absorption.
Water is absorbed through osmosis, while mineral nutrients are taken up by active transport or diffusion.
