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प्रश्न
Explain the role of tapetum in the formation pollen-grain wall.
उत्तर
Tapetum is the anther's innermost wall layer. The cells in this stratum contain big nuclei and thick cytoplasm. This layer is extremely important physiologically since it receives the majority of food from the outside. At maturity, these cells degenerate and nourish the developing microspores or pollens inside. Tapetum is the layer that secretes hormones as well as enzymes.
The major role of tapetum is to provide nutrients to pollens, but it also secretes certain extremely important chemicals such as:
- Callase enzyme: Tapetum secretes a callase enzyme, which dissolves callose compounds and joins four pollens of a pollen tetrad, thereby separating microspores or pollens of a tetrad.
- Ubisch bodies: Tapetum secretes lipid-based substances as well. Ubisch bodies are covered with sporopollenin, increasing the thickness of the exine (the outer layer of the pollen wall). Ubisch bodies are spheroidal, with a diameter of barely a few microns. These are produced exclusively by glandular tapetum.
- Pollenkitt substances: Tapetum also secretes pollenkitt, an outermost oily, thick, viscous, sticky, electron-dense homogenous covering of pollen grains in many entomophilic plants.
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संबंधित प्रश्न
A flower of brinjal plant following the process of sexual reproduction produces 360 viable seeds.
Answer the following questions giving reasons:
(a) How many ovules are minimally involved?
(b) How many megaspore mother cells are involved?
(c) What is the minimum number of pollen grains that must land on stigma for pollination?
(d) How many male gametes are involved in the above case?
(e) How many microspore mother cells must have undergone reduction division prior to dehiscence of anther in the above case?
Arrange the following terms in the correct developmental sequence:
Pollen grain, sporogenous tissue, microspore tetrad, pollen mother cell, male gametes.
One of the most resistant known biological material is ______.
How many microspore mother cells are required to produce 1000 microspores/pollen grains?
Transfer of pollen grains from the anther to the stigma of another flower of the same plant is called ______.
Number of prothallial cells present in male gametophyte of flowering plant is ______.
Generative cell was destroyed by laser but a normal pollen tube was still formed because ______.
How many pollen grains will be formed after meiotic division in 10 microspore mother cells?
The innermost layer of anther is tapetum whose function is ______.
Callase enzyme which dissolves callose of pollen tetrads to separate four pollens is provided by ______.
Study of pollen grains is called ______.
What is the function of germ pore?
When the pollen of a flower is transferred to the stigma of another flower on the same plant, the process is known as ______.
Meiosis does not occur in the organisms showing haplontic life cycle.
On observing the pollen grain under the microscope, it was found to belong and ribbon shaped. The flower-bearing these pollen grains will be pollinated by: ______
Lateral conjugation in Spirogyra takes place in the cells of ______.
Heliophytes are ______.
Male gametophyte in angiosperms produces ______
In some members of which of the following pairs of families, pollen grains retain their viability for months after release?
Draw a neat and well labelled diagram of T.S. of anther.
