What are plant hormones?
These are organic compounds which is synthesized by cells and tissues of plants called plant hormones/ phytohormones. They actively promote, or inhibit some factors and developmental processes of plants. five major groups of plants hormones are present:-
1. Auxin:- it stimulates cell elongation in stems by the protein expansin, which has low pH, 4.5. The amount of xylem and phloem ratio are regulated by auxin.
2. Gibbererllin:- It promotes the internodal elongation of plants. It also helps in seed germination by activating vegetative growth of embryo in plants.
3.Cytokinin:- It involves the cell division in which formation, maintainance and growth of root apical meristem and shoot apical meristem by cytokinin's both positive regulators in shoot apical meristem and negative regulators in root apical merisrtem. Also helps in chloroplast maturation.
4. Abscisic acid:- It is also known as stress hormone which acts in the stress condition of a plant (eg. closing of stomata in extremely drought conditon). It also promotes the root and shoot growth with seed dormancy and germination, also includes wilting of leaves.
5. Ethylene:- It is a gaseous hormone, present in almost every plant because it is responsible for may factors like flowering, fruit ripening, rooting and also for senescence (depends on its concentration).
Metallic oxides of zinc, magnesium and copper were heated with the following metals.
| Metal | Zinc | Magnesium | Copper |
|---|---|---|---|
| Zinc oxide | |||
| Magnesium oxide | |||
| Cooper oxide |
In which cases will you find displacement reactions taking place?
Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows.
| Metal | Iron(II) sulphate | Cooper(II) sulphate | Zinc sulphate | Silver nitrate |
| A | No reaction | Displacement | ||
| B | Displacement | No reaction | Displacement | |
| C | No reaction | No reaction | No reaction | No reaction |
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Welcome to the NCERT Solutions for Class 10 Science - Chapter . This page offers a step-by-step solution to the specific question from Excercise 2 , Question 1: What are plant hormones?....
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