MODEL PAPER 2 — Science STD 10 — Question

Plant Movement
Tropic movement or tropism
Directional movement of specific part of plant in response to external stimuli is called tropism.
These movements are very slow. The movement of plant part can be either towards or away from stimulus.
If the movement of plant is towards stimulus, it is called positive stimulus.
If the movement of plant is away from stimulus, it is called negative stimulus.
1) Phototropism: It is the directional movement of plant part in response to light stimulus.
If plant part move towards light it is called as positive phototropism.
For Ex:Stem or shoot
If plant part move away from light it is called as negative phototropism.
For Ex:Roots
2) Geotropism: It is the response to gravity.
If the plant part moves in the direction of gravity it is called positive geotropism
For Ex:Roots grow downwards.
If the plant part moves against the direction of gravity it is called negative geotropism.
For Ex:Stem grows upwards
3) Chemotropism: Response to chemical stimuli.
If Plant part move towards chemical stimuli it is positive chemotropism
If plant part move away from chemical stimuli it is negative chemotropism.
4) Hydrotropism: Response to water.