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Study of Phototropism and Geotropism in Plants

Materials Required

  • Two un-branched plants   
  • Adhesive tape
  • Cotton 
  • Two boiling tubes marked as A and B  
  • Water 
  • Two laboratory stands with clamps 

 

Real Lab Procedure

  • Take two boiling tubes labelled as A and B.
  • Fill up both the tubes with water until they are two-thirds full.
  • Insert the plant one by one into each boiling tube.
  • Introduce the cotton swabs in such a way that roots dip in water and the stem with leaves project out of the boiling tubes.
  • Seal the mouth of the two boiling tubes using adhesive tape such that no water trickles out of the boiling tube even when they are inverted.
  • Fix tube A vertically upright in a laboratory stand.
  • Fix the other boiling tube B upside down in another laboratory stand.
  • Ensure that the water in second tube (B) does not trickle down.
  • Place the two laboratory stands near a window such that direct sunlight falls on the two plants.
  • Observe the plants in each boiling tube on Day 1, Day 2,  Day 3  and day 4.

 

Simulator Procedure (as performed through the Online Labs)

  • Drag and drop one plant to the marked boiling tube A containing water (Make sure that roots dip in water and the stem with leaves project out of the boiling tubes).
  • Drag and drop one plant to the marked boiling tube B containing water (Make sure that roots dip in water and the stem with leaves project out of the boiling tubes).
  • Drag and drop two cotton swabs into top of the corresponding two boiling tubes.
  • Drag and drop adhesive tape into the mouth of two boiling tubes for sealing.
  • Drag and drop boiling tube A vertically upright in the laboratory stand.
  • Drag and drop boiling tube B upside down in another laboratory stand.
  • Click on the next button to go to next screen of simulator.
  • You can see the observation of Day 1, Day 2, Day 3, and Day 4 on screen. Corresponding to each day, movement of clock will be shown along with the movement of Plants A and B towards sunlight.
  • Click on the ‘Next’ button after Day 4 observation.
  • Drag and drop the correct answers from control panel to appropriate places towards the empty boxes.
  • If the option dragged is wrong, it will go back to its original place.
  • Click on the information icon to see the inference.
  • You can redo the experiment anytime by clicking on the ‘Reset’ button.

 

Observation

The stem in test tube A grows vertically upwards and bends towards the light. The stem in test tube B shows a curvature and bends upwards towards the light and away from the gravitational force, thus showing +ve phototropism and –ve geotropism.

 The roots in both the test tubes grow towards the gravitational force and grow away from sunlight thus exhibiting -ve phototropism and +ve geotropism.