Class XII Chapter 1 – Reproduction In Organisms Biology
Class XIIChapter 1 – Reproduction in OrganismsBiologyQuestion 1:Why is reproduction essential for organisms?AnswerReproduction is a fundamental feature of all living organisms. It is a biologicalprocess through which living organisms produce offspring’s similar to them.Reproduction ensures the continuance of various species on the Earth. In theabsence of reproduction, the species will not be able to exist for a long time and maysoon get extinct.Question 2:Which is a better mode of reproduction sexual or asexual? Why?AnswerSexual reproduction is a better mode of reproduction. It allows the formation of newvariants by the combination of the DNA from two different individuals, typically oneof each sex. It involves the fusion of the male and the female gamete to producevariants, which are not identical to their parents and to themselves. This variationallows the individual to adapt to constantly changing and challenging environments.Also, it leads to the evolution of better suited organisms which ensures greatersurvival of a species. On the contrary, asexual reproduction allows very little or novariation at all. As a result, the individuals produced are exact copies of their parentsand themselves.Question 3:Why is the offspring formed by asexual reproduction referred to as clone?AnswerA clone is a group of morphologically and genetically identical individuals.In the process of asexual reproduction, only one parent is involved and there is nofusion of the male and the female gamete. As a result, the offsprings so producedare morphologically and genetically similar to their parents and are thus, calledclones.Page 1 of 9Website: www.vidhyarjan.comEmail: contact@vidhyarjan.comMobile: 9999 249717Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051(One Km from ‘Welcome’ Metro Station)
Class XIIChapter 1 – Reproduction in OrganismsBiologyQuestion 4:Offspring formed due to sexual reproduction have better chances of survival. Why?Is this statement always true?AnswerSexual reproduction involves the fusion of the male and the female gamete. Thisfusion allows the formation of new variants by the combination of the DNA from two(usually) different members of the species. The variations allow the individuals toadapt under varied environmental conditions for better chances of survival.However, it is not always necessary that the offspring produced due to sexualreproduction has better chances of survival. Under some circumstances, asexualreproduction is more advantageous for certain organisms. For example, someindividuals who do not move from one place to another and are well settled in theirenvironment. Also, asexual reproduction is a fast and a quick mode of reproductionwhich does not consume much time and energy as compared to sexual reproduction.Question 5:How does the progeny formed from asexual reproduction differ from those formed bysexual ctionthe fusion of the male and the femalegamete. uctionAsexual reproduction does not involve1.Progenyundergoing thisreproductionthatareproducemorphologicallyand genetically identical to them.Sexualreproductioninvolvesthefusion of the male and the femalegamete of two individuals, typicallyoneofeachsex.Organismsundergoing this kind of l to them.Page 2 of 9Website: www.vidhyarjan.comEmail: contact@vidhyarjan.comMobile: 9999 249717Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051(One Km from ‘Welcome’ Metro Station)
Class XII2.Chapter 1 – Reproduction in OrganismsOffsprings thus produced do not showvariations and are called ons from each other and theirparents.Question hyisvegetativereproduction also considered as a type of asexual reproduction?AnswerSexual reproduction12.It involves the fusion of the male andIt does not involves the fusion of thefemale gamete.male and the female he3.Asexual reproductionindividualsproducedarenotidentical to their parents and showvariations from each other and also,from their parents.4.5.It requires only one individual.The individuals produced are identicalto the parent and are hence, calledclones.Most animals reproduce sexually. BothAsexual modes of reproduction aresexualcommon in organisms having simpleandasexualmodesofreproduction are found in plants.organizations such as algae and fungi.It is a slow process.It is a fast process.Vegetative propagation is a process in which new plants are obtained without theproduction of seeds or spores. It involves the propagation of plants through certainvegetative parts such as the rhizome, sucker, tuber, bulb, etc. It does not involvePage 3 of 9Website: www.vidhyarjan.comEmail: contact@vidhyarjan.comMobile: 9999 249717Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051(One Km from ‘Welcome’ Metro Station)
Class XIIChapter 1 – Reproduction in OrganismsBiologythe fusion of the male and the female gamete and requires only one parent. Hence,vegetative reproduction is considered as a type of asexual reproduction.Question 7:What is vegetative propagation? Give two suitable examples.AnswerVegetative propagation is a mode of asexual reproduction in which new plants areobtained from the vegetative parts of plants. It does not involve the production ofseeds or spores for the propagation of new plants. Vegetative parts of plants such asrunners, rhizomes, suckers, tubers, etc. can be used as propagules for raising newplants.Examples of vegetative reproduction are:1. Eyes of potato:The surface of a potato has several buds called eyes. Each of these buds whenburied in soil develops into a new plant, which is identical to the parent plant.2. Leaf buds of Bryophyllum:The leaves of Bryophyllum plants bear several adventitious buds on their margins.These leaf buds have the ability to grow and develop into tiny plants when the leavesget detached from the plant and come in contact with moist soil.Page 4 of 9Website: www.vidhyarjan.comEmail: contact@vidhyarjan.comMobile: 9999 249717Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051(One Km from ‘Welcome’ Metro Station)
Class XIIChapter 1 – Reproduction in OrganismsBiologyQuestion 8:Define(a) Juvenile phase,(b) Reproductive phase,(c) Senescent phase.Answer(a) Juvenile phase:It is the period of growth in an individual organism after its birth and before itreaches reproductive maturity.(b) Reproductive phase:It is the period when an individual organism reproduces sexually.(c) Senescent phase:It is the period when an organism grows old and loses the ability to reproduce.Question 9:Higher organisms have resorted to sexual reproduction in spite of its complexity.Why?AnswerAlthough sexual reproduction involves more time and energy, higher organisms haveresorted to sexual reproduction in spite of its complexity. This is because this modeof reproduction helps introduce new variations in progenies through the combinationof the DNA from two (usually) different individuals. These variations allow thePage 5 of 9Website: www.vidhyarjan.comEmail: contact@vidhyarjan.comMobile: 9999 249717Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051(One Km from ‘Welcome’ Metro Station)
Class XIIChapter 1 – Reproduction in OrganismsBiologyindividual to cope with various environmental conditions and thus, make theorganism better suited for the environment. Variations also lead to the evolution ofbetter organisms and therefore, provide better chances of survival. On the otherhand, asexual reproduction does not provide genetic differences in the individualsproduced.Question 10:Explain why meiosis and gametogenesis are always interlinked?AnswerMeiosis is a process of reductional division in which the amount of genetic material isreduced. Gametogenesis is the process of the formation of gametes. Gametesproduced by organisms are haploids (containing only one set of chromosomes), whilethe body of an organism is diploid. Therefore, for producing haploid gametes(gametogenesis), the germ cells of an organism undergo meiosis. During theprocess, the meiocytes of an organism undergo two successive nuclear and celldivisions with a single cycle of DNA replication to form the haploid gametes.Question 11:Identify each part in a flowering plant and write whether it is haploid (n) or diploid(2n).(a) Ovary ———————————(b) Anther ———————————(c) Egg ———————————(d) Pollen ———————————(e) Male gamete ———————————(f ) Zygote ———————————Answer(a) Ovary Diploid (2n)(b) Anther Diploid (2n)(c) Egg Haploid (n)Page 6 of 9Website: www.vidhyarjan.comEmail: contact@vidhyarjan.comMobile: 9999 249717Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051(One Km from ‘Welcome’ Metro Station)
Class XIIChapter 1 – Reproduction in OrganismsBiology(d) Pollen Haploid (n)(e) Male gamete Haploid (n)(f ) Zygote Diploid (2n)Question 12:Define external fertilization. Mention its disadvantages.AnswerExternal fertilization is the process in which the fusion of the male and the femalegamete takes place outside the female body in an external medium, generally water.Fish, frog, starfish are some organisms that exhibit external fertilization.Disadvantages of external fertilization:In external fertilization, eggs have less chances of fertilization. This can lead to thewastage of a large number of eggs produced during the process.Further, there is an absence of proper parental care to the offspring, which results ina low rate of survival in the progenies.Question 13:Differentiate between a zoospore and a zygote.AnswerZoospore1.2.ZygoteA zoospore is a motile asexual sporeA zygote is a non-motile diploid cellthat utilizes the flagella for movement.formed as a result of fertilization.It is an asexual reproductive structure.It is formed as a result of sexualreproduction.Question 14:Differentiate between gametogenesis from embryogenesis.AnswerPage 7 of 9Website: www.vidhyarjan.comEmail: contact@vidhyarjan.comMobile: 9999 249717Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051(One Km from ‘Welcome’ Metro Station)
Class XIIChapter 1 – Reproduction in OrganismsBiologyGametogenesisEmbryogenesisIt is the process of the formation of haploidIt is the process of the development ofmale and female gametes from diploidthe embryo from the repeated mitoticmeiocytes through the process of meiosis.divisions of the diploid zygote.Question 15:Describe the post-fertilization changes in a flower.AnswerFertilization is the process of the fusion of the male and the female gamete to form adiploid zygote. After fertilization, the zygote divides several times to form anembryo. The fertilized ovule forms a seed. The seed contains an embryo, enclosed ina protective covering, called the seed coat. As the seed grows further, other floralparts wither and fall off. This leads to the growth of the ovary, which enlarges andripens to become a fruit with a thick wall called the pericarp.Question 16:What is a bisexual flower? Collect five bisexual flowers from your neighborhood andwith the help of your teacher find out their common and scientific names.AnswerA flower that contains both the male and female reproductive structure (stamen andpistil) is called a bisexual flower. Examples of plants bearing bisexual flowers are:(1) Water lily ( Nymphaea odorata)(2) Rose (Rosa multiflora )(3) Hibiscus (Hibiscus Rosa-sinensis )(4) Mustard ( Brassica nigra)(5) Petunia (Petunia hybrida)Page 8 of 9Website: www.vidhyarjan.comEmail: contact@vidhyarjan.comMobile: 9999 249717Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051(One Km from ‘Welcome’ Metro Station)
Class XIIChapter 1 – Reproduction in OrganismsBiologyQuestion 17:Examine a few flowers of any cucurbit plant and try to identify the staminate andpistillate flowers. Do you know any other plant that bears unisexual flowers?AnswerCucurbit plant bears unisexual flowers as these flowers have either the stamen orthe pistil. The staminate flowers bear bright, yellow coloured petals along withstamens that represent the male reproductive structure. On the other hand, thepistillate flowers bear only the pistil that represents the female reproductivestructure.Other examples of plants that bear unisexual flowers are corn, papaya, cucumber,etc.Question 18:Why are offspring of oviparous animals at a greater risk as compared to offspring ofviviparous animals?AnswerOviparous animals lay eggs outside their body. As a result, the eggs of these animalsare under continuous threat from various environmental factors. On the other hand,in viviparous animals, the development of the egg takes place inside the body of thefemale. Hence, the offspring of an egg-laying or oviparous animal is at greater riskas compared to the offspring of a viviparous animal, which gives birth to its youngones.Page 9 of 9Website: www.vidhyarjan.comEmail: contact@vidhyarjan.comMobile: 9999 249717Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051(One Km from ‘Welcome’ Metro Station)
Class XIIChapter 2 – Sexual Reproduction in Flowering PlantsBiologyQuestion 1:Name the parts of an angiosperm flower in which development of male and femalegametophyte take place.AnswerThe male gametophyte or the pollen grain develops inside the pollen chamber of theanther, whereas the female gametophyte (also known as the embryo sac) developsinside the nucellus of the ovule from the functional megaspore.Question 2:Differentiate between microsporogenesis and megasporogenesis. Which type of celldivision occurs during these events? Name the structures formed at the end of thesetwo ntetradsMegasporogenesisprocessoffromaoftheIt is the process of the formation of themicrosporefour megaspores from a megasporemicrosporemother cell in the region of the nucellusmother cell through meiosis.2.It occurs inside the pollen sacof the anther.through meiosisIt occurs inside the ovule.(b) Both events (microsporogenesis and megasporogenesis) involve the process ofmeiosis or reduction division which results in the formation of haploid gametes fromthe microspore and megaspore mother cells.(c) Microsporogenesis results in the formation of haploid microspores from a diploidmicrospore mother cell. On the other hand, megasporogenesis results in theformation of haploid megaspores from a diploid megaspore mother cell.Page 1 of 10Website: www.vidhyarjan.comEmail: contact@vidhyarjan.comMobile: 9999 249717Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051(One Km from ‘Welcome’ Metro Station)
Class XIIChapter 2 – Sexual Reproduction in Flowering PlantsBiologyQuestion 3:Arrange the following terms in the correct developmental sequence:Pollen grain, sporogenous tissue, microspore tetrad, pollen mother cell, malegametesAnswerThe correct development sequence is as follows:Sporogenous tissue – pollen mother cell – microspore tetrad – Pollen grain – malegameteDuring the development of microsporangium, each cell of the sporogenous tissueacts as a pollen mother cell and gives rise to a microspore tetrad, containing fourhaploid microspores by the process of meiosis (microsporogenesis). As the anthermatures, these microspores dissociate and develop into pollen grains. The pollengrains mature and give rise to male gametes.Question 4:With a neat, labelled diagram, describe the parts of a typical angiosperm ovule.AnswerAn ovule is a female megasporangium where the formation of megaspores takesplace.The various parts of an ovule are –Page 2 of 10Website: www.vidhyarjan.comEmail: contact@vidhyarjan.comMobile: 9999 249717Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051(One Km from ‘Welcome’ Metro Station)
Class XIIChapter 2 – Sexual Reproduction in Flowering PlantsBiology(1) Funiculus – It is a stalk-like structure which represents the point of attachmentof the ovule to the placenta of the ovary.(2) Hilum – It is the point where the body of the ovule is attached to the funiculus.(3) Integuments –They are the outer layers surrounding the ovule that provideprotection to the developing embryo.(4) Micropyle – It is a narrow pore formed by the projection of integuments. Itmarks the point where the pollen tube enters the ovule at the time of fertilization.(5) Nucellus – It is a mass of the parenchymatous tissue surrounded by theinteguments from the outside. The nucellus provides nutrition to the developingembryo. The embryo sac is located inside the nucellus.(6) Chalazal – It is the based swollen part of the nucellus from where theinteguments originate.Question 5:What is meant by monosporic development of female gametophyte?AnswerThe female gametophyte or the embryo sac develops from a single functionalmegaspore. This is known as monosporic development of the female gametophyte.In most flowering plants, a single megaspore mother cell present at the micropylarpole of the nucellus region of the ovule undergoes meiosis to produce four haploidmegaspores. Later, out of these four megaspores, only one functional megasporedevelops into the female gametophyte, while the remaining three degenerate.Question 6:With a neat diagram explain the 7-celled, 8-nucleate nature of the femalegametophyte.AnswerPage 3 of 10Website: www.vidhyarjan.comEmail: contact@vidhyarjan.comMobile: 9999 249717Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051(One Km from ‘Welcome’ Metro Station)
Class XIIChapter 2 – Sexual Reproduction in Flowering PlantsBiologyThe female gametophyte (embryo sac) develops from a single functional megaspore.This megaspore undergoes three successive mitotic divisions to form eight nucleateembryo sacs.The first mitotic division in the megaspore forms two nuclei. One nucleus movestowards the micropylar end while the other nucleus moves towards the chalazal end.Then, these nuclei divide at their respective ends and re-divide to form eightnucleate stages. As a result, there are four nuclei each at both the ends i.e., at themicropylar and the chalazal end in the embryo sac. At the micropylar end, out of thefour nuclei only three differentiate into two synergids and one egg cell. Together theyare known as the egg apparatus. Similarly, at the chalazal end, three out of fournuclei differentiates as antipodal cells. The remaining two cells (of the micropylar andthe chalazal end) move towards the centre and are known as the polar nuclei, whichare situated in a large central cell. Hence, at maturity, the female gametophyteappears as a 7-celled structure, though it has 8 nucleate.Question 7:What are chasmogamous flowers? Can cross-pollination occur in cleistogamousflowers? Give reasons for your answer.AnswerThere are two types of flowers present in plants namely Oxalis and Viola chasmogamous and cleistogamous flowers. Chasmogamous flowers have exposedanthers and stigmata similar to the flowers of other species.Page 4 of 10Website: www.vidhyarjan.comEmail: contact@vidhyarjan.comMobile: 9999 249717Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051(One Km from ‘Welcome’ Metro Station)
Class XIIChapter 2 – Sexual Reproduction in Flowering lowers.ThisBiologyisbecausecleistogamous flowers never open at all. Also, the anther and the stigma lie close toeach other in these flowers. Hence, only self-pollination is possible in these flowers.Question 8:Mention two strategies evolved to prevent self-pollination in flowers.AnswerSelf-pollination involves the transfer of pollen from the stamen to the pistil of thesame flower. Two strategies that have evolved to prevent self-pollination in flowersare as follows:(1) In certain plants, the stigma of the flower hasthecapability to prevent thegermination of pollen grains and hence, prevent the growth of the pollen tube.It is ageneticmechanism
Class XII Chapter 1 – Reproduction in Organisms Biology Page 4 of 9 Website: www.vidhyarjan.com Email: contact@vidhyarjan.com Mobile: 9999 249717 Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051 (One Km from ‘Welcome’ Metro Station) the fusion of the male and the female gamete and requires only one parent.
Number of Clusters XII-9. C) Overlap XII-10. D) An Example XII-10. 5. Implementation XII-13. A) Storage Management XII-14. 6. Results XII-14. A) Clustering Costs XII-15. B) Effect of Document Ordering XII-19. Cl. Search Results on Clustered ADI Collection . XII-20. D) Search Results of Clustered Cranfield Collection. XII-31. 7. Conslusions XII .
Part One: Heir of Ash Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18 Chapter 19 Chapter 20 Chapter 21 Chapter 22 Chapter 23 Chapter 24 Chapter 25 Chapter 26 Chapter 27 Chapter 28 Chapter 29 Chapter 30 .
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TO KILL A MOCKINGBIRD. Contents Dedication Epigraph Part One Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Part Two Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18. Chapter 19 Chapter 20 Chapter 21 Chapter 22 Chapter 23 Chapter 24 Chapter 25 Chapter 26
reproduction and the reasons why both reproductive strategies still persist today are also explored. Timeline 00:00:00 Reproduction 00:02:24 Types of asexual reproduction 00:06:12 Sexual reproduction in animals 00:10:10 Sexual reproduction in flowering plants 00:12:33 Asexual and sexual reproduction - advantages and disadvantages
Class- XII-CBSE-Biology Reproduction in Organisms Practice more on Reproduction in Organisms Page - 1 www.embibe.com. CBSE NCERT Solutions for Class 12 . Biology. Chapter 1 . Back of Chapter Questions . 1. Why is reproduction essential for organisms? Solution: Reproduction is one of the salient features of all organisms. It is a biological process
TEKNIK PEMESINAN GERINDA 1 Program Studi: Teknik Pemesinan Kode: TM.TPM-TPG 1 (Kelas XII-Semester 5) . Teknik Pemesinan Frais (TM.TPM-TPF) Teknik Pemesinan Bubut (TM.TPM-TPB) TM.TPM- TPB1 (XI-3) (XII-5) TM.TPM- TPB 2 (XI-4) TM.TPM- TPB 3 TM.TPM- TPB 4 (XII-6) TM.TPM-TPF 1 (XI-3) TM.TPM-TPF 2 (XI-4) TM.TPM-TPF 3 (XII-5) TM.TPM-TPF 4 (XII-6) TM.TPM-TPG 1 (XII-5) TM-MK/EM 1 (X-1) TM.TPM-TPC)1 .
Class XII – NCERT – Biology Chapter 3 Human Reproduction 3. Human Reproduction . Question 3: Draw a labelled diagram of female reproductive system. Solution 3: Question 4: Write two major functions each of testis and ovary. Solution 4: Functions of the Testis They produce male game
