Q2 of 36 Page 261

Give the scientific terms used to represent the following:

A. Bending of a shoot towards light.


B. Growing of roots towards the earth.


C. Growing of a pollen tube towards ovule.


D. Bending of roots towards water.


E. Winding of tendril around a support.

A. Positive phototropism. The growth of shoot takes place in the direction of light, that is towards the stimulus. Hence, positive phototropism.

Picture showing positive and negative phototropism.



B. Positive geotropism. The stimulus in the case of geotropism is gravity. As the growth of roots is towards the earth, i.e. under the force of gravity. Hence, positive geotropism.


C. Chemotropism. The growth of pollen tube is in response to the chemicals released by the ovule during fertilization.


D. Hydrotropism. The movement of plant part in response to water is known as hydrotropism.


E. Thigmotropism. Movement of plant part in response to touch is known as thigmotropism.


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