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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 was asked to observe and identify the various parts of an embryo of a red kidney bean seed. He identified the parts and listed them as under:
I. Tegmen
II. Testa
III. Cotyledon
IV. Radicle
V. Plumule
The correctly identified parts among these are
(A) I, II and III
(B) II, III and IV
(C) III, IV and V
(D) I, III, IV and V
"The chromosomal number of the sexually producing parents and their offspring is the same." Justify this statement.
Give one example of a unisexual flower.
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
The anther contains ______.
Where are the pollen grains produced?
What is the name of female part of a flower?
Fill in the following blank with suitable word :
Ovules contain ......... gametes of a plant.
Fill in the following blank with suitable word :
Flowering plants reproduce by ...........method of reproduction.
Give some examples of different modes of fertilisation in nature?
What type of plants reproduce by sexual reproduction method?
How does pollination occur?
The part of a seed which grows and develops into root on germination is :
(a) cotyledon
(b) plumule
(c) follicle
(d) radicle
Fill in the blank by selecting suitable word:
A flower bearing only male or female parts is known as __________ flower.
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 Stigma.
“Cell division is a type of reproduction in unicellular organism.” Justify.
Draw a diagram of a pistil showing pollen tube growth into the ovule and label the following:
Pollen grain, male gamete, female gamete, ovary.
List any two differences between pollination and fertilization.
Identify the odd. Stigma, Style, Pollen, Ovary.
Explain sexual reproduction in plants.
Prepare a slogan for campaign against female foeticide.
Differentiate between self-pollination and cross-pollination.
What is meant by pollination?
Write the functions of sepals
Explain the sexual reproduction process in plants with a diagram.
Match the following
| 1. | Petal | Opuntia |
| 2. | Fern | Chrysanthemum |
| 3. | Phylloclade | Attracts insect |
| 4. | Hooks | Spore |
| 5. | Sucker | Bignonia |
Which of the following is the outermost protective layer of anther?
Complete the table
| Carly x | ______ | ______ |
| ______ | petal | attract insects |
| Androecium | ______ | Male reproductive part |
| ______ | ______ | Female reproductive part. |
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
In a bisexual flower inspite of the young stamens being removed artificially, the flower produces fruit. Provide a suitable explanation for the above situation.
Give any two examples of agents of pollination.
What are the agents for pollination?
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.
State the post-fertilisation changes that lead to fruit formation in plants.
