Class 7 | Science | Chapter 12 | Reproduction in Plants | NCERT Solutions
Question 1. Fill in the blanks:
(a) Production of new individuals from the vegetative part of 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) Production of new individuals from the vegetative part of parent is called vegetative propagation.
(b) A flower may have either male or female reproductive parts. Such a flower is called unisexual flower.
(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 pollination.
(d) The fusion of male and female gametes is termed as fertilisation.
(e) Seed dispersal takes place by means of wind, water and animal.
Question 2. Describe the different methods of asexual reproduction. Give examples.
Answer 2 The different methods of asexual reproduction are :
1) Vegetative propagation: The new plant are produced from the parts of old plants(like stems, roots or leaves).It involves the growth and development of one or more buds on the old part of the plant to produce a new plant.Some of the plants which are usually reproduced by the method of vegetative propagation are rose, potato, ginger, turmeric, sweet potato, mint, sugarcane.
2) Budding: In budding, a small part of the body of the parent plant grow out as a bulb like projection called bud which then detaches and becomes a new plant.
For Ex: Yeast
3) Fragmentation: The breaking up of the body of a plant into two or more pieces on maturing , each of which subsequently grows to form a new plant, is called fragmentation.The green patches on the lakes or water bodies are due to the growth of plant like organism called algae.They reproduce by this method.
For Ex: Spirogyra
4) Spore formation:In this method of reproduction, parent produces hundreds of tiny spores.When the spore of the plant bursts, then the spores spread into air.Each spore has a hard protective coat to withstand unfavourable conditions.When the air borne spores land on food under favourable conditions , they germinate and produce new plants.
For Ex: Most of the fungi, flowerless plants, bread mould plant or rhizopus.
Question 3. Explain what you understand by sexual reproduction.
Answer 3 When two parents are involved in reproduction, the method is called sexual reproduction. The male and female gametes fuse during fertilization to produce zygote. The zygote subsequently develops into an embryo which further develops into a new individual.
Question 4. State the main difference between asexual and sexual reproduction.
|Asexual Reproduction||Sexual Reproduction|
|It involves only one parent.||It involves two parents.|
|Gametes are not produced.||Gametes are produced.|
|Characteristic of only one parent is inherited.||Characteristics of both the parents are inherited.|
|It requires only mitotic division.||It requires meiotic division followed by mitotic division.|
|Fertilisation is not seen.||Fertilisation of gametes give rise to zygote.|
|For Ex: Yeast, hydra, Spirogyra||For Ex: Animals, human being, insects|
Question 5. Sketch the reproductive parts of a flower.
Answer 5 Pistil is the female reproductive organ of a plant.
Stamen is the male reproductive organ of a plant
Question 6. Explain the difference between self-pollination and cross-pollination.
|It is the transfer of pollen grains to sigma of same flower.||It is the transfer of pollen grains to stigma of another flower of same plant or another plant. of same kind.|
|It does not require any external agency.||It requires external agent such as wind, water, insects|
|Both anther and stigma matures at same time.||Anther and stigma matures at different times.|
|It occurs even when the flower is closed.||It occurs when the flower is open.|
|For Ex: Peanuts, sunflower||For Ex: Mango, rose|
Question 7. How does the process of fertilisation take place in flowers?
Answer 7 When a pollen grain falls on the stigma of the pistil, the pollen grains grows a pollen tube downwards through the style towards the female gamete in the ovary.A male gamete moves down the pollen tube.The pollen tube enters the ovule in the ovary.The tip of pollen tubes burst open and male gametes comes out of pollen tube.In ovary, the male gamete of pollen combines with the female gamete present in the ovule to form a fertilised egg called zygote.The zygote develops into an embryo.
Question 8. Describe the various ways by which seeds are dispersed.
Answer 8 The various ways by which seeds are disperse are:
1) Dispersal by Wind: Seeds of some plants are light-weight and have wing-like structures present on them. Such seeds float on air and are thus dispersed by wind.
Example: Dandelion, maple, drumstick, etc.
2) Dispersal by Water: Dispersal by water takes place in some aquatic plants and in some which grow near a water body.
Seeds of water lily float and thus dispersed by water.
The coconut seed has a tough fibrous covering which has plenty of air inside. This helps the coconut seeds in floating on water.
3)Dispersal by Animals: Some seeds have spine like structures on them. They get stuck to the fur of animals and thus get spread to different places.
Examples: Beggar tick, Xanthium, etc. Some seeds are swallowed by birds and animals along with fruits. These seeds get dispersed with bird or animal droppings.
4) Dispersal by Bursting: Some fruits burst open when they mature. The force of bursting is enough to spread the seeds.
Examples; Ladyfinger, castor, balsam, etc.
5)Dispersal by Humans: Human beings also help in dispersal of seeds, especially during farming
Question 9. 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
Column I Column II
(a) Bud (iii) Yeast
(b) Eyes (v) Potato
(c) Fragmentation (ii) Spirogyra
(d) Wings (i) Maple
(e) Spores (iv) Bread mould
Question 10. 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 organism is
(ii) bread mould
(e) Bryophyllum can reproduce by its
Answer 10)(a) (iv) flower
(b) (i) fertilisation.
(c)( iv) fruit.
(d) (ii) bread mould.
(e) (ii) leaves