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प्रश्न
What is double fertilisation? Describe the process in brief.
उत्तर
Double fertilization is a major characteristic of flowering plants. In this process, two male gametes fuse with one female gamete wherein one male gamete fertilizes the egg to form a zygote, whereas the other fuses with two polar nuclei to form endosperm.
Double fertilization gives stimulus to the plant that results in the development of the ovary into fruit and ovules into seed. The fusion of haploid male and female gametes restores the diploid condition of the plant.
Process of double fertilisation:
- After successful pollination, the pollen grain germinates on the stigma to form the pollen tube.
- The pollen tube carries in the cytoplasm two male gametes and one tube nucleus into the ovary.
- The pollen tube enters the ovary mostly through the micropyle region, near the egg apparatus. This movement is guided by the filiform apparatus.
- Inside the ovary, the pollen tube absorbs water and bursts open, releasing the two male gametes and the tube nucleus.
- The tube nucleus degenerates, and the two male gametes prepare for fusion.
- One of the male gamete fuses with the egg cell to form the diploid zygote.
- The other male gamete fuses with the diploid secondary nucleus to form the primary endosperm nucleus (PEN).
- The zygote develops to form the new plant, while the PEN develops to form the endosperm, which provides nourishment to the developing embryo.
संबंधित प्रश्न
Where and how does triple fusion take place?
Explain the events up to double fertilisation after the pollen tube enters one of the synergids in an ovule of an angiosperm.
Fill in the blanks with suitable words.
Transference of pollen grains from anthers to stigma of the same flower is called ________.
Give one word/term for the following:
When pollen grains of a flower reach the stigma of the same flower.
What happens to the following after fertilization?
Ovules
What are the advantages of the following in the flower to the plant concerned?
Smooth and light pollen
Given ahead is a diagrammatic sketch of the sectional view of a germinating pollen grain. Study the same and then answer the question that follows:
Where does the germination of the pollen grain take place and how?
Given ahead is a diagrammatic representation of the process of fertilization. Study the same and then answer the question that follows:
Name the parts labelled 1, 2, 3, 4, 5 and 6.
Given ahead is a diagrammatic representation of the process of fertilization. Study the same and then answer the question that follows:
What is the function of the synergids?
Define fertilization.
What happens to the ovary post fertilization?
The question has four options. Choose the correct answer:
When only ovary forms fruits they are known as
After fertilization the ovule becomes ______.
Identify the incorrect pair
The correct order of haploid, diploid, and triploid structure in fertilized embryo sac is
Male gametes in angiosperms are formed by the division of ______.
Transmitting tissue is found in
Define triple fusion.
Name the cell which divides to form male nuclei.
Give a concise account of the steps involved in the fertilization of an angiosperm plant.
Pollen tube was discovered by
By which of the following the megasporangium proper of an angiosperm ovule is represented?
By which of the following double fertilization is exhibited?
What would be the number of chromosomes in the megaspore mother cell of the plant if an endosperm of an angiosperm has 24 chromosomes?
Double fertilization and triple fusion were discovered by ______.
In ______ sepal is seen on the fruit after fertilization.
What is the function of the two male gametes produced by each pollen grain in angiosperms?
Identity the part of embryo sac which takes part in formation of primary endosperm nucleus during fertlisation
What is Siphonogamy?
