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प्रश्न
Why does self-pollination not lead to seed formation in self-incompatible species?
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उत्तर
Self-incompatibility is a gene-physiological event. A single gene, known as the S-gene, regulates incompatibility reactions and contains many alleles. Pollen grains with the S-allele, which is shared by either of the two alleles in pistil cells, won’t work on that pistil. However, any pollen grain that does not share S-alleles with the pistil will function on that plant’s pistil. Self-pollens are unable to fertilize the egg, preventing the formation of an embryo; hence, seeds do not form in self-incompatible species.
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संबंधित प्रश्न
Why do moss plants produce very large number of male gametes? Provide one reason. What are these gametes called?
A flower of tomato plant following the process of sexual reproduction produces 240 viable seeds.
Answer the following questions giving reasons :
(a) What is the minimum number of pollen grains that must have been involved in the pollination of its pistil?
(b) What would have been the minimum number of ovules present in the ovary?
(c) How many megaspore mother cells were involved?
(d) What is the minimum number of microspore mother cells involved in the above case?
(e) How many male gametes were involved in this case?
What is self-incompatibility?
What is meant by emasculation?
Describe the structure of its microsporangium.
Find the odd-one out, giving reason:
Ovary, style, pollen grain, stigma
Complete the following chart and rewrite.
| Sr.No. | Agencies | type of pollination |
| 1 | Water | .................... |
| 2 | ........................... | Entomophily |
| 3 | Bat | .................... |
| 4 | ....................... | Ornithophily |
(Or)
Explain outbreeding devices in angiospermic plants.
State the name of the chief pollinating agent against the corresponding plant by choosing from those given in brackets.
Dahlia_______ .
When maturation time of reproductive parts in a flower is different.
Give one word/term for the following:
When stigma and anthers do not grow up to the same height, which favors only cross-pollination.
Type of interaction where an individual sacrifices its own welfare (life) for the benefit of another animal of its own species is ______.
What is a flower? Draw a typical flower and label its different parts.
Differentiate Between Cross Pollination and Self Pollination:
What are the adaptations which are required in self-pollinated plants?
Pollination occurs in ______.
Which of the following pair has haploid structures?
Chief pollinators of agricultural crops are ______.
The flower which possesses both androecium and gynoecium is called perfect or ______.
Pollination refers to the ______.
Correct definition of pollination is ______
The term used for transfer of pollen grains from anthers of one plant to stigma of a different plant which, during pollination, brings genetically different types of pollen grains to stigma, is ______
Mention any one example of the hydrophilous flower.
What is hypohydrophily?
What is epihydrophily?
Briefly discuss any two methods by which plants avoid self-pollination.
When and why does a plant breeder employ the emasculation technique?
Identify the set of correct statements:
- The flowers of Vallisneria are colourful and produce nectar.
- The flowers of waterlily are not pollinated by water.
- In most of water-pollinated species, the pollen grains are protected from wetting.
- Pollen grains of some hydrophytes are long and ribbon like.
- In some hydrophytes, the pollen grains are carried passively inside water.
Choose the correct answer from the options given below:
Bird pollinated flowers are usually ______.
