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प्रश्न
Explain sexual reproduction in plants.
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उत्तर
- In sexually reproducing plants, flowers function as the reproductive organs.
- In flowers, the male organ is the stamen and the female organ is the carpel.
- Flowers which have both the male and female organs, i.e. stamens and carpels, are called bisexual flowers, whereas flowers which have either male or female organs are called unisexual.
- Male gametes, called pollen grains, are produced by stamens, and carpels produce female gametes, called ovules or egg cells, inside ovaries.
- Fertilization takes place in the ovule where the egg cell and pollen grain fuse.
- This fertilized egg cell later develops into an embryo and the entire ovule gets converted into a seed.
- Under favourable conditions, the seed germinates to give rise to a new plant.
APPEARS IN
संबंधित प्रश्न
You are asked by your teacher to study the different parts of an embryo of a gram seed. Given below are the steps to be followed for the experiment:
I. Soak the gram seeds in plain water and keep them overnight.
II. Cut open a soaked seed and observe its different parts.
III. Take some dry gram seeds in a petri dish.
IV. Drain the excess water.
V. Cover the soaked seeds with a wet cotton cloth and leave them for a day.
The correct sequence of these steps is :
(A) III, I, V, IV, II
(B) III, I, II, IV, V
(C) III, IV, V, I, II
(D) III, I, IV, V, II
Explain what you understand by sexual reproduction.
Sketch the reproductive parts of a flower.
State the name of the functional unit concerned with sexual reproduction.
Fill in the following blank with suitable word :
Flowering plants reproduce by ...........method of reproduction.
Fill in the following blank with suitable word :
The name of the structure in the flower in which the male gamete is formed is...........
Fill in the following blank with suitable word :
The.......... at the base of the carpel contains egg cells.
Fill in the following blank with suitable word :
The term used to refer to the transfer of pollen from the stamen of one flower to the carpel of another flower of the same species is...........
What is made in anther of a flower?
What is made in ovary of a flower?
How do the insects help in cross-pollination?
Name the part of a seed which contains stored food.
Name the part of a seed which grows into shoot.
Which among the following statements are true for unisexual flowers?
(i) They possess both stamen and pistil
(ii) They possess either stamen or pistil
(iii) They exhibit cross pollination
(iv) Unisexual flower possessing only stamens cannot produce fruits
(a) (i) and (iv)
(b) (ii), (iii) and (iv)
(c) (ii) and (iii)
(d) (i), (iii) and (iv)
When an insect sits on the flower of a plant then some particles A present in the top of little stalks in the flower attach to its body hair. When this insect now sits on the flower of another similar plant, then particles A attached to the hair of insect are put on the top of a flask-shaped organ at the centre of flower. The particle A grows a long tube b from the top of flask-shaped organ through which C moves down and reaches the bottom part of flask-shaped organ. Here C fuses with the nucleus of d contained in structure E. the fusion of C and D forms a new cell f which grows and develops into a seed of the plant.
(a) What are particles A? What is the process of transferring A from one flower to another flower of similar plant by the insect known as?
(b) What is the name of tube B?
(c) What is C which moves down through the tube B?
(d) Name D and E.
(e) What is F?
Describe an activity to demonstrate phototropism.
Which of the following is not an unisexual flower?
a) Coconut
b) Papaya
c) Gulmohor
d) Maize
Find the odd one out:
Calyx : Sepals : : Corolla : ________________
Bisexual : Hibiscus : : Unisexual : ___________
Draw a neat and labelled diagram.
Double fertilization in angiosperms
Match the following
| 1. | Petal | Opuntia |
| 2. | Fern | Chrysanthemum |
| 3. | Phylloclade | Attracts insect |
| 4. | Hooks | Spore |
| 5. | Sucker | Bignonia |
The essential parts of a flower are ______.
Where does the endothecium layer of anther lobes is present?
Which of the following are the chemical components of the wall of pollen tube?
Identify the female gametophyte in angiosperms.
What would be the number of chromosomes of the aleurone cells of a plant with 42 chromosomes in its roots tip cells?
Sperm and egg nuclei fuse due to ______.
What would be the number of chromosomes in the cells of the aleurone layer in a plant species with 8 chromosomes in its synergids?
In human beings, fertilization occurs in the ______
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?
Trace the path a male gamete takes to fertilise a female gamete after being released from the penis.
Double fertilization is essential for formation of ______.
Triple fusion involves ______.
In flowering plants, the pollen grains are transferred to stigma by pollination but the female germ cells are present in the ovary.
Explain with the help of a labelled diagram (only concerned parts), how the male germ cell reaches the ovary.
Given below is a diagram of a germinating seed. Label the parts that:
- gives rise to future shoot.
- gives rise to future root system.
- stores food.
The number of pollen sacs in a dithecous anther is ______.
