ICSE 2019: Given below is an experimental set-up to demonstrate a particular tropic movement in germinating seeds.

ICSE 2019:

Q. Given below is an experimental set-up to demonstrate a particular tropic movement in germinating seeds. Study the diagram and answer the questions that follow: [5 marks]

 (i)  Label the parts 1 and 2.

(ii) Name the tropic movement shown by part 1.

(iii) Part 1 is affected by two stimuli. Name them. Which one of the two is stronger?

(iv) What is thigmotropism? Give one example.

(v) What is meant by ‘positive’ and ‘negative’ tropic movements in plants?

Solution:

(i) Labeling:

• Part 1 : Radicle 
• Part 2 : Plumule

(ii) The tropic movement shown by Part 1 is Hydrotropism.

(iii) Part 1 is affected by two stimuli namely, gravity and water.

The stimulus by water is stronger than gravity.

(iv) The directional growth movement of plant in response to touch stimuli is called Thigmotropism.

Example: 

Coiling movement of Tendrils in the direction of an object that touches it.

(v) Tropic movement in plants towards the stimulus is positive tropic movement whereas 

tropic movement in plants away from the stimulus is negative tropic movement. 

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