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प्रश्न
Why do you think the zygote is dormant for sometime in a fertilised ovule?
उत्तर
After fertilisation, the zygote develops in the ovule. The integuments of the ovule harden and form the seed coat. The outer integument of the ovule forms the seed coat and the inner integument forms the inner coat. Food materials start getting accumulated in the endosperm. The amount of water gradually decreases, hence, the soft ovule becomes hard and dry. Gradually, the functional activities inside the ovule stop and the new embryo formed from the zygote reaches a dormant state. This is called zygote dormancy. This structure surrounded by seed coat, containing the accumulated food and dormant embryo is called seed.
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संबंधित प्रश्न
'Formation of primary endosperm nucleus is called triple fusion'. Give reason
Double fertilization is reported in plants of both, castor and groundnut. However, the mature seeds of groundnut are non-albuminous and castor are albuminous. Explain the post fertilization events that are responsible for it.
Read the following statement and answer the questions that follow :
"A guava fruit has 200 viable seeds."
(a) What are viable seeds?
(b) Write the total number of :
(i) Pollen grains (ii) Gametes
in producing 200 viable guava seeds.
c) Prepare a flow-chart to depict the post-pollination events leading to viable-seed production in a flowering plant.
Describe any two devices in a flowering plant which prevent both autogamy and geitonogamy.
Match the items in Column A with those in Column B.
|
Column A |
Column B |
|
(a) Generative nucleus |
(i) Pollen tube |
|
(b) Germ pore |
(ii) Endosperm nucleus |
|
(c) Exine |
(iii) Testa |
|
(d) Secondary nucleus |
(iv) Fertilization |
|
(e) Integument |
(v) Male nuclei |
|
(f) Egg nucleus |
(vi) Rough |
What happens to the following after fertilization?
Petals
What are the advantages of the following in the flower to the plant concerned?
Fragrant nectar
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:
Name the parts labelled 1, 2, 3, 4 and 5.
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 happens to
i) Ovary
ii) Ovule after fertilisation
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 is the function of pollen tube? Explain with the help of a diagram.
Explain double fertilization and its significance.
Describe the process of double fertilization.
Long Answer Question:
Draw a labeled diagram of the L.S. of anatropous ovule and list the components of the embryo sac and mention their fate after fertilization.
Why fertilization process in angiosperms is called as double fertilization?
Give any four points of significance of double fertilization.
Pollen tube was discovered by
Assertion: Sporopollenin preserves pollen in fossil deposits
Reason: Sporopollenin is resistant to physical and biological decomposition
The correct order of haploid, diploid, and triploid structure in fertilized embryo sac is
Syngamy results in the formation of ______.
Which of the following represent megagametophyte
Write a short note on Pollen kitt.
By which of the following the megasporangium proper of an angiosperm ovule is represented?
Identify the CORRECT statement with reference to cellular endosperm.
What would be the number of chromosomes in the megaspore mother cell of the plant if an endosperm of an angiosperm has 24 chromosomes?
Through which route the pollen tube can enter the ovule?
Double fertilization is fusion of ______.
In ______ sepal is seen on the fruit after fertilization.
Ovules fall off after fertilization.
Find out the CORRECT sequence of events taking place in pollen - pistil interaction.
- Pollen tube enters one of the synergids and bursts to release male gametes.
- Pollen tube enters the ovule through the micropyle of the ovary.
- The pollen tube grows through the stigmatic tissue and then style.
- Pistil recognizes the correct pollen and accepts it.
In the diagram given below, show the path of a pollen tube from the pollen on the stigma into the embryo sac. Name the components of egg apparatus.
What is the function of the two male gametes produced by each pollen grain in angiosperms?
In the figure given below label the following parts: male gametes, egg cell, polar nuclei, synergid and pollen tube
Identity the part of embryo sac which takes part in formation of primary endosperm nucleus during fertlisation
What is Siphonogamy?
