Reproduction in Plants
Fill in the blanks :
(a) Production of new individuals from the vegetative part of a parent is called ………. .
(b) A flower may have either male or female reproductive parts. Such a flower is called ………. .
(c) The transfer of pollen grains from the anther to the stigma of the same or of another flower of the same kind is known as ………. .
(d) The fusion of male and female gametes is termed as ………. .
(e) Seed dispersal takes place by means of ………. , ………. and.
(a) vegetative propagation
(b) unisexual flower
(e) wind; water; animals.
Describe the different methods of asexual reproduction. Give examples.
Various methods of asexual reproduction are :
(i) Vegetative propagation :
It is a type of asexual reproduction in which new plants are produced from roots, stems, leaves and buds. Since reproduction takes place through the vegetative parts of the plant, it is known as vegetative propagation.
(ii) Budding :
Here, the small bulb-like projection coming out from, yeast cell is called a bud, gradually grows and gets detached from the parent cell and forms organism, e.g., yeast. The new yeast grows, matures and produces more yeasts. If this process continues, a large number of yeasts are produced in a short time.
(iii) Fragmentation :
This type of reproduction is common in algae. These are slimy green patches in ponds, or in other stagnant water bodies. When water and nutrients are available algae grow and multiply rapidly by fragmentation An algae breaks up into two or more fragments. These fragments or pieces grow into new individuals. This process continues and they cover a large area in a short period of time.
(iv) Spore formation :
The fungi on a bread piece grows due to spores which are present in the air. When spores are released, they keep floating in the air. As they are very light, they can travel over long distances. The spores are asexual reproductive bodies.
Each spore is covered by a hard protective coat to withstand unfavourable condition such as high temperature and low humidity. So, they can survive for a long time. Under favourable conditions, a spore germinates and develops into a new individual. Plants such as moss and ferns also reproduce by means of spores.
Explain what you understand by sexual reproduction.
Sexual reproduction means involvement of two parents in the process of reproduction. It is found mainly in higher plants, where male gamete and female gamete fuse to form a zygote.
These zygotes develop into individuals which are not identical. Offsprings inherit the characteristics of both the parents. In sexual reproduction, both parents survive after the process of reproduction.
State the main difference between asexual and sexual reproduction.
In sexual reproduction, seed is required but in asexual reproduction seed is not required.
Sketch the reproductive parts of a flower.
Explain the difference between self-pollination and cross-pollination;
If the pollen lands on the stigma of the same flowers it is called self-pollination. When the pollen of a flower lands on the stigma of another flower of the same plant, or that of a different plant of the same kind, it is called cross-pollination.
How does the process of fertilisation take place in flowers?
When the pollen grain reaches the stigma of a same species flower, it starts growing out into the pollen tube of the stigma. This tube continues to grow inside the style till it reaches the ovule. Male cells are released into the ovule for fertilisation with the female egg cell and thus the zygote is formed. After this process of fertilisation, the ovary develops into fruit and ovule into seeds.
Describe the various ways by which seeds are dispersed.
Seeds and fruits of plants are carried away by the following ways :
(i) Dispersion by wind :
Winged seeds such as those of drumstick and maple, light seeds of grasses or hairy seeds of aak CMadar) and hairy fruit of sunflower get blown off with the wind to far away places.
(ii) Dispersion by water :
Some seeds are dispersed by water. These fruits or seeds usually develop floating ability in the form of spongy or fibrous outer coat as in coconut.
(iii) Dispersion by animals :
Some seeds are dispersed by animals, especially spiny seeds with hooks which get attached to the bodies of animals and are carried to distant places. Examples are Xanthium and Urena.
(iv) Dispersion by explosion :
Some seeds are dispersed when the fruits burst with sudden jerks. The seeds are scattered far from the parent plant. This happens in the case of castor and balsam.
Match items in Column I with those in Column II :
|Column I||Column II|
|(a) Bud||(i) Maple|
|(b) Eyes||(ii) Spirogyra|
|(c) Fragmentation||(iii) Yeast|
|(d) Wings||(iv) Bread mould|
|(e) Spores||(v) Potato|
Tick () the correct answer :
(a) The reproductive part of a plant is the
(b) The process of fusion of the male and the female gametes is called
(iv) seed formation
(c) Mature ovary forms the
(d) A spore producing plant is
(ii) bread mould
(e) Bryophyllum can reproduce by its
(d)-(ii) bread mould