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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
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
State significance of pollination.
Give one example of a unisexual flower.
Explain what you understand by sexual reproduction.
Name the part made up of the stigma, style and ovary.
Name the swollen lower part of the carpel.
Fill in the following blank with suitable word :
The male organ of reproduction in the flower is the.......... .
Name the part of a seed which grows into shoot.
Describe the process of fertilisation in a flower with the help of labelled diagrams.
What changes take place in the flower after fertilisation which lead to the formation of seeds and fruit?
(a) Draw a neat diagram of a flower showing its various parts. In this diagram mark stem, receptacle, sepals, petals, stamen and carpel.
(b) What name is given to (i) all the petals of a flower, and (ii) all the sepals of a flower?
(c) What are (i) stamen, and (ii) carpel, in a flower?
(d) What is the other name of carpel of a flower?
(e) What is the name of yellow powdery substance present in the anther of a flower?
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
Which of the following statements are true for flowers?
(i) Flowers are always bisexual.
(ii) They contain sexual reproductive organs.
(iii) They are produced in all groups of plants.
(iv) after fertilization they give rise to fruits.
In the figure given alongside, the parts marked A, B and C are sequentially :
(a) cotyledon, plumule and radicle
(b) plumule, radicle and cotyledon
(c) plumule, cotyledon and radicle
(d) radicle, cotyledon and plumule
The correct sequence of reproductive stages occurring in flowering plants is ______
In what ways is fertilisation in a plant similar to fertilisation in a human?
Put a tick mark (✓) against the correct alternative in the following statement
Reproductive whorls of a flower are:
Fill in the blanks:
A stamen consists of ______ and ________.
State whether the following statement is true (T) or false (F):
Flowers which possess stamens and carpel are called unisexual.
Mention the function of Flower.
Mention the function of Anther.
Mention the function of Stigma.
Distinguish between unisexual and bisexual flowers giving one example of each. Draw a diagram showing process of germination of pollen grains on stigma and label the following parts:
(a) Female germ cell
(b) Male germ cell
(c) Ovary
Sketch the labeled diagram:
Flower with its sexual reproductive organs
Fill in the blanks and rewrite the completed statements:
Lymph flows in _______________ direction.
Pollen grains are formed by _________ division in locules of anthers.
Calyx : Sepals : : Corolla : ________________
Generally, in a pollen tube, which of the following moves to the tip of the tube?
Identify the female gametophyte in angiosperms.
Sperm and egg nuclei fuse due to ______.
The seed that contains the future plant is called the ______
Pollen grains are produced by ______
Which out of the following processes does not lead to the formation of clones.
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?
The ovaries of different flowers may contain ______.
State the number of sets of chromosomes present in a zygote.
Double fertilization is essential for formation of ______.
What are the agents for pollination?
Triple fusion involves ______.
