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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
How does fertilisation occur in flowers? Name the parts of the flower that develop into (i) seed, and (ii) fruit after fertilisation.
Name the parts A, B and C shown in the following diagram and state one function of each.
The anther contains ______.
The process of fusion of the male and female gametes is called ______.
Where are the pollen grains produced?
What is the function of a flower?
Where is the female gamete formed in flowering plants?
Fill in the following blank with suitable word :
The ovule becomes a .......... after fertilisation.
Draw a neat sketch of the stamen of a flower. Mark in it filament and anther.
What is seed?
Name the part of a seed which grows into root.
In what ways is fertilisation in a plant different from fertilisation in a human?
State whether the following statement is true (T) or false (F):
Flowers which possess stamens and carpel are called unisexual.
A student is asked to study the different parts of an embryo of pea seeds. Given below are the essential steps for the experiment :
(I) Soak the pea seeds in plain water and keep them overnight.
(II) Cut open the soaked seed and observe its different parts.
(III) Take some pea seeds in a petri dish.
(IV) Drain the excess water. Cover the seeds with a wet cotton cloth and leave them as it is for a day.
The correct sequence of these steps is
(A) III, I, IV, II
(B) III, IV, I, II
(C) III, I, II, IV
(D) III, II, I, IV
Prepare a slogan for campaign against female foeticide.
__________ is present in unisexual flower.
Calyx : Sepals : : Corolla : ________________
Observe the figure below. Write functions of the labelled parts.
The male reproductive part of a flower is ______.
In which part of the flower germination of pollen grains takes place?
The anther wall consists of four wall layers where ______
Which of the following are the chemical components of the wall of pollen tube?
How many middle layers are generally present in the wall of the anther lobes?
Gloriosa superba exhibits ______.
Sperm and egg nuclei fuse due to ______.
Conidia are formed endogenously while zoospores are formed endogenously.
Which out of the following processes does not lead to the formation of clones.
Which among the following statements are true for unisexual flowers?
- They possess both stamen and pistil
- They possess either stamen or pistil
- They exhibit cross pollination
- Unisexual flowers possessing only stamens cannot produce fruits
The ovaries of different flowers may contain ______.
Double fertilization is exhibited by ______
Double fertilization is essential for formation of ______.
What is the function of calyx?
The pollen tube usually enters the embryo sac ______.
Explain the post fertilization changes that occur in the ovary of a flower.
State the post-fertilisation changes that lead to fruit formation in plants.
In male reproductive whorl of a flower the archesporial cells are formed by ______.
The number of pollen sacs in a dithecous anther is ______.
