Question

Identify the modes of asexual
organisms :
(i) Hydra →
(ii) Planaria
(iii)Amoeba -
(iv) Spirogyra
(v) Rhizopus


(b)
List three advantages of vegetative propagation.
(c)Why can fertilisation not take place in flowers if pollination does
not occur?
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Answer 1

Question:

Identify the modes of asexual reproduction in the following organisms.

(i) Hydra

(ii) Planaria

(iii) Amoeba

(iv) Spirogyra

(v) Rhizopus

Answer:

Asexual reproduction refers to the mode of reproduction where an organism gives rise to new individual/s without the formation or fusion of gametes.

Examples of asexual reproduction include Budding, Binary fission, Multiple fission, Regeneration, Fragmentation etc.

(i) Hydra $\longrightarrow$ Budding & Regeneration.

(ii) Planaria  $\longrightarrow$ Regeneration.

(iii) Amoeba $\longrightarrow$ Primarily by Binary fission, Multiple fission.

(iv) Spirogyra $\longrightarrow$ Fragmentation.

(v) Rhizopus $\longrightarrow$ Spore formation.

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Question:

List three advantages of vegetative propagation.

Answer:

Vegetative reproduction refers to the propagation of offsprings through the vegetative parts/propagules of a plant body. (Through leaves, roots, stems)

• It's the only way to propagate plants that have lost their ability to produce viable seeds.

• Plants raised by vegetative propagation can bear fruits and flowers earlier than the plants produced by seeds.

• It's Cheaper, and a faster and easier method of propagation of plants.

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Question:

Why can fertilisation not take place in flowers if pollination doesn't occur?

Solution:

Fertilisation refers to the fusion of a male & female gamete (germ cells), resulting in the formation of a new individual. Pollination refers to the transfer of a pollen grain from the anther of a flower onto the stigma of the same flower or another flower. If pollination doesn't take place, there will be no fusion of the male and female gamete, which in turn will result in no fertilisation.

Answer 2

Answer:

A] (i) Hydra is an example of regeneration and budding.

(ii) Planaria is an example of regeneration.

(iii) Amoeba is an example of binary fission.

(iv) Spirogyra is an example of fragmentation.

(v) Rhizopus is an example of spore formation.

EXTRA INFORMATION :-

Asexual reproduction is a type of reproduction in which fusion of gametes does not take place and only one parent is involved in the process of reproduction.

The different types of a sexual reproduction are spore formation, vegetative propagation, building, regeneration, fragmentation, binary fission and multiple fission.

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B] Three advantages of vegetative propagation are as follows :-

1. The plants raised by this method can bear flowers and fruits.
2. This method also make it possible for the propagation of plants such as banana, orange, etc. that have lost the capacity to produce seeds.
3. All the plants produced by this method are genetically similar to the parent plant.
4. They have all the characteristics similar to their parent plant.

EXTRA INFORMATION :-

Vegetative propagation is a type of asexual method of reproduction in which an offspring is produced by a vegetative part of a plant. The vegetative part of a plant includes roots, stems and leaves, etc. Sometimes vegetative propagation involves human interference in the processes like layering or grafting to grow many plants for agricultural purposes.

Example :- Bryophyllum (The vegetative part is leaf)

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C] Pollination is the process of transfer of pollen grains from anther to stigma. Fertilisation is the process of fusion of male gamete and female gamete. In plants, if transfer of pollen grains from anther to stigma does not take place, it is obvious that the process of fertilization will not take place because pollen grains are male gametes. Hence, we can conclude that, fertilization does not take place in flowers of pollination does not take place.

EXTRA INFORMATION :-

In plants, flower is the main component which helps in reproduction. The male parts of the flower include anther and filament together called as stamen. The female parts of the flower include stigma, style and ovary together called as carpel or pistil. The pollen grains from the anther of the male parts of the flower sticks on the stigma of the female part of the flower. Here, then a pollen tube is formed through the style of the the female part of the flower. Through the pollen tube formed, the pollen grains reaches the ovary for the process of fertilization. Ovary contains the female gamete - ovule.

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