Pea seedlings were treated as follows; Seedling A - Coleoptiles tip was cut off, metal block placed, then tip placed back. Seedling B - Coleoptiles tip was...

      

Pea seedlings were treated as follows;
Seedling A - Coleoptiles tip was cut off, metal block placed, then tip placed back.
Seedling B - Coleoptiles tip was cut off, agar block placed then tip placed back.
Seedling C - Was left intact.
The seedlings A, B and C were placed in dark box with a small hole at one side as illustrated in the diagram below;
pic18920191104.png
a) State what was being investigated in the set up above.
b) Using diagrams illustrate how the seedlings A, B and C appear after 48 hours.
c) Explain the results in (b) above;

  

Answers


sharon
a) i) Response of shoot to unidirectional light.
ii) Role of tip in response
pic18920191107.png
c) Seedling A - No growth, no response, metal prevented auxins from tip from diffusing to the region of growth/auxins did not pass through the metal block.
Seedling B - Auxins from tip diffused through agar, light from one direction caused more auxins to be distributed to side away from light; caused more cell elongation than on the lighted side, hence curvature towards direction of light.
Seedling C - Auxins from tip diffused to region of cell elongation; unidirectional light caused unequal distribution of auxins; more auxins on the side away from light caused more growth; resulting in positive phototropism.
sharon kalunda answered the question on September 18, 2019 at 08:08


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