Class-7, Science, Chapter:- 12 Reproduction In Plants Notes, NCERT Solutions & Frequently Asked Questions
Science
Class:-7, Chapter:- 12
Reproduction In Plants
Notes, NCERT Solutions & Frequently Asked Questions
-- Notes --
⭐Reproduction:- The process of producing offspring by the parent is called reproduction.
➧ It is a biological process.
➧ The offspring produced can and cannot be the exact copy of the parent.
⭐Parts of Plants:- Plants have two kinds of parts:-
Vegetative Parts - These are the parts of the plant that plays a major role in the life cycle of a plant such as preparation of food, transportation of food, water and nutrients etc. For Example, roots, stems and leaves.
Reproductive Parts - These are the parts of a plant that play a major role in the reproduction process in plants, For Example, flowers, fruits.
⭐Mode of Reproduction:- There are two modes of reproduction, asexual reproduction and sexual reproduction.
a) Asexual Reproduction:- Reproduction that occurs without the involvement of male and female gamete is called asexual reproduction.
➧ Only one parent is involved in asexual reproduction.
➧ Seed is not produced in this mode of reproduction.
➧ Different Types of the Asexual Reproductions are:-
i) Vegetative Propagation:- Reproduction that occurs through vegetative part of the plant i.e., leaves, stems, vegetative buds and roots is called vegetation propagation.
• Eg.- -- Onion, garlic and tulip are produced by the stems
-- potato, ginger & turmeric can grow through vegetative buds
-- sweet Potato and Dahlia are produced by the roots
-- bryophyllum is produced by leaves.
{⧫Advantages of Vegetative Propagation:-
• Plants produced with vegetative reproduction takes less time to grow and bear flower and fruits earlier than those produced from seeds.
• The new plants are the exact copies of parent plant because they are produced from a single parent.}
ii) Budding:- Bud is the small bulb-like structure bulging from the parent cell.
• Bud when it gets detached it develops into a new organism and this process of producing new organism from the bud when it gets detached is called budding.
• Eg.- yeast and hydra.
iii) Fragmentation:- The process by which organisms get divided into a number of fragments and each fragment develops into a new individual is called fragmentation.
• Eg.- Spirogyra
iv) Spore Formation:- The process by which organisms get divided into a number of spores and each spore develops into a new individual under favorable conditions is called spore formation.
• Eg.- fungi, fern and bacteria
b) Sexual Reproduction:- Reproduction that occurs with the involvement of male and female gametes is called sexual reproduction.
➧ Seed is produced in this mode of reproduction.
➧ This reproduction occurs through the reproductive part of the plant - flower.
➧ The flower has both male reproductive parts called stamens and female reproductive part called pistil / carpels.
➧ Stigma, style and ovary together forms pistil / carpels.
➧ Filament & the anther together forms stamens.
➧ Male gamete (pollen grains) are produced by anthers and female gamete (ovule) is produced by pistil / carpels, fuses to form a zygote.
➧ Flowers that has either pistil or stamens is called unisexual flowers and flowers that has both pistil and stamens is called bisexual flowers.
⭐Pollination:- When pollen is transferred from the anther to the stigma of a flower is called pollination. Pollination is of two types:-
a) When the pollen of a flower lands on the stigma of the same flower or another flower of the same plant it is called self-pollination.
b) When the pollen of a flower lands on the stigma of a flower of different plant, it is called cross-pollination.
⭐Zygote:- In sexual reproduction a male and a female gamete fuse to form a zygote.
➧ So in case of plants, the male gametes present in the pollen grains fuse with the female gamete i.e. egg.
➧ This fusion is called as fertilization and the cell formed out of the fusion is called as a zygote.
⭐Fertilization:- Fertilization is the phenomena of fusion of the male gamete with the female gamete cell to form Zygote.
⭐Embryo:- The zygote further develops to form the embryo.
➧ In animals, the embryo grows into an adult.
➧ In Plants, the embryo further gives rise to shoot system and root system.
⭐Fruits and Seed Formation:-
➧ In plants, post fertilization, the ovary develops into a fruit and other parts of the flower fall off.
➧ The ripened ovary forms the fruit.
➧ The ovules form the seeds.
⭐Seed Dispersal:- Seeds and fruits of plants are dispersed away by wind, water and animals.
➧ The seeds show different characteristics depending on their dispersing agent.
a) Seed Dispersal by Wind:- Seeds are winged and light to get carried by the wind. eg: maple and drumstick.
• Hairy seeds of aak (Madar) and hairy fruit of sunflower.
b) Seed Dispersal by Water:- These seeds or fruits normally develop the ability of floating in the form of fibrous or spongy outer coat.
• Eg.- coconut.
c) Seed Dispersal by Animals:- Spiny seeds with hooks that are attached to the animal body and are hence carried to distant places.
• Eg.- Xanthium, Urena
➧ Few of the seeds disperse when the fruits burst out with a sudden jerk, which gets scattered away to a distance far from the parent plant. Eg.- Balsam and Castor.
⭐Benefits of Seed Dispersals:-
➧ Seed dispersal avoids overcrowding of young plants around their parent plants.
➧ It helps in preventing competition between the plants and its own seedlings for sunlight, water and minerals.
➧ It enables the plant to grow into new habitats for wider distribution and provides them with a better chance of survival.
⭐Germination of Seed:- A seed contains a plant embryo in a resting state which begin to grow only under favourable conditions.
➧ The process by which seeds begin to grow is called seed germination. It is the growth of a plant from its seed.
➧ When the seed germinates, the seed coat splits and a tiny root called radicle grows downward and shoot called plumule starts growing upwards. This produces seedling of the plant.
-- 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 __________.
Answer:-
(a) vegetative reproduction
(b) unisexual flower
(c) pollination
(d) fertilization
(e) wind, water
Question 2.- Describe the different methods of asexual reproduction. Give examples.
Answer:- Different methods of asexual reproduction are:-
a) Binary Fission:- This process takes place in unicellular organisms. Parent cell elongates and gets divided into two identical daughter cells. Each daughter cell grows into an independent adult.
b) Fragmentation:- In this process, body of the organism breaks up into two parts. Then each part grows into a new filament thus forming two organisms from a single one.
c) Spore Formation:- The spores are tiny spherical unicellular structures protected by thick wall. The spores are stored in a hard outer covering and this is called sporangium. Under favourable conditions the hard cover breaks and spores spread for germination.
d) Budding:- In yeast, new organisms are produced by the bud formation from the parent organism. After growing to full size, the bud gets detached and forms a new independent individual.
e) Vegetative propagation:- When vegetative parts of a plant like stems, leaves and root etc., give rise to new ones, it is.called vegetative propagation.
Question 3.- Explain what you understand by sexual reproduction.
Answer:- 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.
Question 4.- State the main difference between asexual and sexual reproduction.
Answer:-
Question 5.- Sketch the reproductive parts of a flower.
Answer:-
Question 6.- Explain the difference between self-pollination and cross-pollination
Answer:-
Question 7.- How does the process of fertilization take place in flowers?
Answer:- 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 the fertilization with the female egg cell and thus the zygote is formed. After this process of fertilization, the ovary develops into fruit and ovule into seeds.
Question 8.- Describe the various ways by which seeds are dispersed.
Answer:- Following are the ways in which the seeds are dispersed:-
i) Some light seeds like that of madar, which are hairy, dry and small are carried away by the wind to different places.
ii) Spiny seeds and fruits like that of xanthium and urena, stick to the clothes of passers by and animals. These seeds are carried away by these agents to different places.
iii) In some plants having heavy seeds like that of coconut, water acts as the dispersing agents.
iv) Some seeds are dispersed with the fruit burst like in case of balsam and castor.
Question 9.- Match items in Column I with those in Column II.
Answer:-
Question 10.- Tick (√) the correct answer:-
a) The reproductive part of a plant is the
i) leaf ii) stem iii) root iv) flower
b) The process of fusion of the male and the female gametes is called
i) fertilisation ii) pollination
iii) reproduction iv) seed formation
c) Mature ovary forms the
i) seed ii) stamen iii) pistil iv) fruit
d) A spore producing plant is
i) rose ii) bread mould
iii) potato iv) ginger
e) Bryophyllum can be reproduced by its
i) stem ii) leaves iii) roots iv) flower
Answer:-
a) - iv) flower
b) - i) fertilisation
c) - iv) fruit
d) - ii) bread mould
e) - ii) leaves
-- Frequently Asked Questions --
Question 1.- What are the parts of a plant?
Answer:- Plants typically have six basic parts: roots, stems, leaves, flowers, fruits and seeds.
Question 2.- Why is the process of reproduction necessary?
Answer:- The process of reproduction is necessary for the perpetuation and preservation of species and to increase the number of members of species.
Question 3.- A flower consists of different parts. Name these parts of a flower.
Answer:- The four main parts of a flower are sepals, petals, stamen & pistil.
Question 4.- Explain sexual reproduction in plants.
Answer:- Sexual reproduction in plants is a process in which both male and female gametes fuse to form a new individual. Pistils and stamens are the female and male reproductive organs in plants which bear ovary and anthers respectively.
- By Durgesh Pandey
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