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प्रश्न
Give scientific reason.
Fertilization in plants is called double fertilization.
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उत्तर
- The pollen grain germinates over the stigma and gives rise to pollen tube.
- The pollen tube bursts and releases two male gametes in the embryo sac.
- One male gamete fuses with the egg cell to form the zygote, whereas the second male gamete fuses with two polar nuclei in the embryo sac to form an endosperm.
- Since, in flowering plants, the process of fertilization occurs twice in the same embryo sac, by two male gametes, it is called as double fertilization.
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संबंधित प्रश्न
What is pollination?
A student while observing an embryo of a pea seed in the laboratory listed various parts of the embryo as given below:
Testa, Tegmen, Radicle, Plumule, Micropyle, Cotyledon.
On examining the list the teacher remarked that only three parts are correct. Select three correct parts from the above list:
(a) Testa, Radicle, Cotyleddon
(b) Tegmen, Radicle, Micropyle
(c) Cotyledon, Plumule, Testa
(d) Radicle, Cotyledon, Plumule
A student has to perform the experiment "To identify the different parts of an embryo of a dicot seed." Select from the following an appropriate group of seeds:
(a) Pea, gram, wheat
(b) Red kidney bean, maize, gram
(c) Maize, wheat, red kidney bean
(d) Red kidney bean, pea, gram
Name the parts labelled as A, B, C and D in the diagram given below:
Explain what you understand by sexual reproduction.
How does the process of fertilisation take place in flowers?
The reproductive part of a plant is the ______.
Mature ovary forms the ______.
State the name of the functional unit concerned with sexual reproduction.
What is the function of a flower?
Fill in the following blank with suitable word :
The female organ of reproduction in the flower is the...........
Draw a neat sketch of the carpel of a flower. Mark in it stigma, style and ovary.
Explain the terms 'cross-pollination'?
How do the insects help in cross-pollination?
In tobacco plant, the male gametes have 24 chromosomes.
What is the number of chromosomes in the zygote?
Which of the following is the correct sequence of events of sexual reproduction in a flower?
(a) pollination, fertilisation, seed, embryo
(b) seed, embryo, fertilisation, pollination
(c) pollination, fertilisation, embryo, seed
(d) embryo, seed, pollination, fertilisation
Fill in the blank by selecting suitable word:
A flower that bears both the male and the female parts is known as __________ flower.
Multiple choice question. Tick (✓) the correct choice:
The male gamete is present inside the which germinates.
- the style
- the stigma
- the anther
- the ovary
Fill in the blank:
Seeds are formed from________.
State whether the following statement is true (T) or false (F):
Stamens make egg cells.
Find the odd one out:
Pollen grains from anther are transferred to the stigma.
Draw a neat and labelled diagram.
Double fertilization in angiosperms
Explain the sexual reproduction process in plants with a diagram.
The male reproductive part of a flower is ______.
The essential parts of a flower are ______.
In which of the following manner the arrangement of megaspores in a tetrad is observed in angiosperms?
Identify the female gametophyte in angiosperms.
The process of release of eggs from the ovary is called ______
Length of pollen tube depends on the distance between ______
Give reason for the following:
Fertilization cannot take place in flowers if pollination does not occur.
Is the chromosome number of zygote, embryonal cells and adult of a particular organism always constant? How is the constancy maintained in these three stages?
Where is the zygote located in the flower after fertilization?
Double fertilization means ______.
What is the function of calyx?
The pollen tube usually enters the embryo sac ______.
- Assertion: Primary endosperm nucleus is diploid.
- Reason: It is the product of double fertilisation.
