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An experiment was carried out to investigate the effect of hormones on growth of lateral buds of three pea plants. The shoots were treated as follows. (a)...

      

An experiment was carried out to investigate the effect of hormones on growth of lateral buds of three pea plants.
The shoots were treated as follows.
(a) Shoot A – Apical bud was removed.
(b) Shoot B – Apical bud was removed and gibberellic acid placed on the cut shoot.
(c) Shoot C – Apical bud was left intact.
The lengths of the branches developing from the lateral buds were determined at regular intervals. The results obtained are shown in the table below.
BIOLOGY3212019416.png
(i) Using the same axes, draw graphs to show the lengths of branches against time.
(ii) (a) What was the length of the branch in Shoot B on the 7th day?
(b) What would be the expected length of the branch developing from Shoot B on the 11th day?
(iii) Account for the results obtained in the experiment.
(iv) Why was Shoot C included in the experiment?
(v) What is the importance of gibberellic acid in agriculture?
vi)State two physiological processes that are brought about by the application of gibberellic acid on plants.

  

Answers


sharon
BIOLOGY3212019427.png
(ii) (a) 104mm -+ 1mm (from 103mm to 105mm)
(b) 164 mm
(iii) A. Removal of apical bud led to less auxin synthesis hence less auxin migrated to the stem;
leading to increase in length of lateral bud;
B. Removal of apical bud led to less auxin migrating to the stem but with addition of G. A
(Gibberellic acid) there is more cell elongation leading to increase in length of the lateral branches;
C. Presence of apical bud led to more synthesis of Auxin; leading inhibition of elongation of
lateral buds hence to slow rate of increase in length of lateral branches;
(iv) To act as a control experiment.
(v) - Help / stimulate formation of side branches.
- Ends dormancy in buds.
- Activate growth of adventitious root.
- Brings about parthenocarpy / initiated flowering / setting fruits without fertilization.
- Break seed dormancy
- Affect leaf expansion.
- Retard leaf abscission.
(vi) - Activates enzymes during germination thus breaking seed dormancy.
- Promote cell division / elogation
sharon kalunda answered the question on March 21, 2019 at 13:32


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