Discovery of plant hormone gibberellins was made by chance. It happened by chance in rice fields. A few plants of rice were observed, which were unusually taller than the normal ones. Scientific investigation revealed, that these were infected with a fungus, known as Gibberella fufikuroi. This fungus releases a plant hormone gibberellic acid in excess concentrations which made the plant to grow unusually tall. This compound was later known as gibberellin is hormones present in all plants.
The term used for accidental finding is Serendipity which means fortunate happenstance. It was coined by Horace Walpole in 1754. He explained it as making discoveries, by accident and sagacity, of things, which were hot in quest of.
The meristematic cells can be identified of the basis of the following characteristics
(i) Cell have thin cellulose wall and dense cytoplasm with large nucleus.
(ii) Plasmodesmal connections are more numerous among meristematic cells.
(iii) Cell division, i.e., mitosis and its various stages are distinctly visible.
(iv) Chromosomes of cells replicate and divide into two homologous chromatids.
All these features contribute to open ended growth where structure is never complete in meristematic regions.
Whereas, cells incapable of divinding show features such as
(i) attains particular shape, size and thickening.
(ii) Undergoes structural and physiological differentiation.
(iii) Different types of cell are formed such as epidermis, cortex, vascular tissues.
Elasticity | Plasticity |
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The elasticity is stretchability of the plant cells or products, e.g., rubber/latex etc. The elastic substances can revert back to its original form in relaxed state. e.g., stretching of rubber. |
Different pathways in response to environment or phases of life to form different kinds of structure is called plasticity. The plastic substances and phenomenon of plasticity are not reversible, i.e., irreversible. e.g., difference in shapes of leaves produced in air and those produced in water in buttercup. This is also known as heterophylly. |
Label the diagram
A. This is which part of a dicotyledonous plants?
B. If we remove part 1 from the plant, what will happen?
Representation the labelling of the given diagram is as follows
A. The plant part in the given diagram is growing shoot apex.
B. Removal of shoot apex will help to overcome the apical dominance. Thus, the lateral buds grow faster, giving rise to branches and give the plant a bushy appearance.