Ans.Significance of pollination are: (iii)The brightly coloured female flowers have long stalk to reach the surface. 6.Outbreeding devices Developed by the bisexual flowers to avoid self-pollination and promote cross-pollination because continuous self-pollination results in poor yield and poor quality of seeds or inbreeding depression. Ans.The two end products of double fertilisation in angiosperms are diploid zygote and a triploid primary endosperm nucleus. 20.Draw a Longitudinal Section (LS) of a post-pollinated pistil showing entry of pollen tube into a mature embryo sac. The continued self-pollination leads to chances of inbreeding depression. [Foreign 2011] In fertilisation (in angiosperm), two types of fusion occur, i.e. (v)Normally, a single ovule is present in the ovary. 11.Why should a bisexual flower be emasculated and bagged prior to artificial pollination? Give any one characteristic of pollen grains produced by such flowers. 2.Differentiate between xenogamy and geitonogamy? Make a list of an y three outbreeding devices that flowering plants have developed and explain how they help to encourage cross-pollination, (a) Differentiate between inbreeding and outbreeding. Mention the reasons for difference in ploidy of zygote and primary endosperm nucleus in an angiosperm. (ii)The events that occur when compatible pollen grains falls on stigma in the sequence are as follow: Give an example of each type. CBSE Board Exams 2021 to be held in Feb-March: CBSE Top Official. The three out breeding devices that flowering plants have developed to encourage cross-pollination are: i. It is basically the phenomenon of acceptance or rejection of pollen grains by the pistil (stigma), which is mediated by chemical components of pollen grain, interacting with that of pistil. (a) List the three states the annuals and biennial angiosperms have to pass through during their life cycle. Question carries 1 marks; ... What do mean by pollination?
(ii) Dichogamy favours cross pollination as it stands as a barrier to self pollination. Join the 2 Crores+ Student community now! Diploid zygote is formed by fusion of haploid gametes, i.e. (i) Geitonogamy is pollen from onethe condition in which flower are deposited on the stigma of another flower borne on the same plant. (ii)Generally a single ovule in each ovary and numerous flowers packed into an inflorescence, e.g. (ii)Explain the events that occurs, upto  fertilisation, when the compatible pollen grain lands on the stigma. syngamy and triple fusion, in the embryo sac. Get Answer to your question from 'Sexual Reproduction in Flowering Plants' by Meritnation Experts with ... Samuel Thomas. 5.Plants like Viola, Oxalis and Commelina produce two types of flowers: These devices are: [All India 2012] (ii)The pollen tube grows and reaches the ovary, enters the ovule through micropyle and then enters one of the synergids. (iii)Draw the next mature stage and label the parts. Numbers and Quadratic Equations, Introduction (i) Well exposed stamens for the pollen grains to be carried away easily. (ii) Self-incompatibility is a genetic process that prevents germination of pollen from the same flower on the stigma. to Three Dimensional Geometry, Application 18/9/12. (ii)Why is geitonogamy also referred to as genetically autogamy? Outbreeding devices: Continued self-pollination result in breeding depression. Solution : Outbreeding devices in Angiospermic plants. Cedars 3. c. The stigmas are large, well-exposed, hairy, and feathery or branched to catch the air-borne pollen grains. to Trigonometry, Complex (iii)What is syngamy? (ii)Cleistogamous flowers are those flowers in which anthers and stigmas lie close to each other and do not open at all, even at maturity. Pines 6. The flowers (male and female) are separate. In artificial hybridisation, desired pollen grains are used for pollination and the stigma is protected from contamination (from unwanted pollen). Anther & stigma mature at different times Dichogamy (v)Protandry       (vi) Protogyny. Make a list of any three outbreeding devices that flowering plants have developed and explain how they help to encourage cross-pollination? It is the characteristic of angiosperms. (i) Write the characteristic features of anther, pollen and stigma of wind pollinated flowers. It is functionally cross-pollination as it involves a pollinating agent but genetically similar to autogamy since, the pollen grains come from the same plant (genetically same parent). Ans.Chasmogamous flowers which are similar to flowers of other species with exposed anthers and stigma favour cross-pollination. (c)pollen tube (d) micropyle. Q.54. Question carries 3 marks; Draw and label a diagram of an ovule. Some of them are  Strategies to prevent self-pollination are: Flowering plants have developed certain outbredding devices to discourage self-pollination and encourage cross-pollination. (vi)Non-essential whorls, calyx and corolla are much reduced or absent. Ans. Primary endosperm nucleus (3n) is formed as a result of triple fusion, i.e. [All India 2009] Ans.The two devices to prevent autogamy in flowering plants are: Describe each one with the help of an example. Plants are dioecious and continued self-pollination may cause inbreeding depression. 4.Biotic agents of pollination are insects, animals, etc. That’s why a bisexual flower should emasculated and bagged prior to artificial pollination, 12.Explain any two devices by which autogamy is prevented in flowering plants. (iii)The second male gamete fuses with the two polar nuclei to form a triploid Primaiy Endosperm Nucleus (PEN). Ans.In wind pollinated flowers: Ans. Flowering plants have evolved outbreeding devices because, Pinus/Cedrus differs from angiospermic plants in the absence of, In angiospermic plants, meiosis of megaspore mother cell generally produces, female gametophyte of angiospermic plants is represented by. syngamy and triple fusion occur in an embryo sac, this is called double fertilisation. (ii)The pollen grains have mucilaginous covering. (ii) One of the male gametes fuses with the egg to form a zygote. Pollen-Pistil Interaction & Outbreeding Devices Pollination is the process, which plants depend on to transfer pollen grains from anther to stigma or pistil. Because the majority of flowering plants produce hermaphrodite flowers and are likely to come in contact with the stigma of the same flower. This device or mechanism promotes out breeding. VIT to Consider JEE Main, SAT Scores for Engineering Admissions. Continued self pollination in plants results in inbreeding depression Explain any three outbreeding devices developed by plants to discourage self pollination - Biology - Sexual Reproduction in Flowering Plants [Foreign 2011] Make a list of outbreeding devices that flowering plants have developed and explain how they help to encourage cross-pollination. Ploidy of cells involved in double fertilisation: Zygote is diploid (2n). [All India 2010 C] [Foreign 2010] (c ) Mention two advantages of inbreeding programme in cattle. It is genetically similar to autogamy but functionally involves cross-pollination. (a)They offer nectar and (edible) pollen grains. These flowers are invariably autogamous and promotes inbreeding depression as there is no chance for cross-pollination at all. Explain. Herkogamy: Flowers possess some mechanical barrier on their stigmatic surface to avoid self-pollination.. 2. fusion of two haploid gametes (male gamete + egg). 7.Pollen-pistil interaction is mediated by chemical components of the pollen interacting with those of pistil. (i)Insect pollinated flowers are generally large, colourful, fragrant and rich in nectar. Explain any two devices by which autogamy is prevented in flowering plants. One of these is not an examples of such outbreeding device. 4.Why do the pollen grains of Vallisneria have a mucilaginous covering? (vi)Non-essential whorls, calyx and corolla are much reduced or absent. Geitonogamy will lead to inbreeding depression because the pollen grains are genetically similar resulting into inbreeding. (iii) Flowers normally packed together as an inflorescence. Some—e.g., date palms (Phoenix dactylifera) and willows (Salix species)—have become dioecious; that is, some plants produce only “male” (staminate) flowers, with the rest producing only “female” (pistillate or ovule-producing) ones. (i)Following compatible pollination, pollen grain germinates on the stigma to produce a pollen tube through a germ pore. (b) List and describe any two vegetative propagules in flowering plants. Q.56. and Inverse Proportions, Areas (iii) In most of the water pollinated species, pollen grains are protected from wetting by mucilaginous covering. (i) Strategies to prevent self-pollination are: (iii)Next mature stage JEE Main could be held 4 times a year from 2021 to reduce the student’s examination stress. NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12. 28.Why is fertilisation in an angiosperm referred to as double fertilisation? This process is called bagging. to Euclids Geometry, Areas CBSE board exam 2021 application date extended for private students. Label the following parts Redwoods 7. 1.Pollination is the transfer of pollen grains from anther to the stigma of a pistil. [Delhi 2011] Ans. (a)Pollen-pistil interactions Once the compatible pollen grains fall on stigma which is receptive, it recognise and accepts the pollen with the aid of chemical components interacting with pollen. Try it now. Get key details of the Education Minister’s live webinar session. [Delhi 2008] Students who are in class 12th or preparing for any exam which is based on Class 12 Biology can refer NCERT Biology Book for their preparation. Know here complete details related to WB class 10 and 12 board exam 2021. [Delhi 2010] Write their fate during the development of seed. Explain. (MARCH-2010) (ii)Name the initial cell from which this structure has developed. Outbreeding devices : Majority of flowering plants produces hermaphrodite flowers which undergo self-pollination. (iii)Unisexuality  (iv) Chasmogamous flowers Appendix 2. Given below in the diagram showing the transfer of pollen grains. [Delhi 2014 C] Inside ovule, the filiform apparatus guides the pollen tube, carrying gametes to the egg. Anthers and stigma   lie close to each other to effect pollination. Explain. (d)By producing unisexual flowers. The following are the three Outbreeding devices used by plants for the prevention of self-pollination: Unisexuality: In sexuality, the plant bears, either male or female flowers. (ii) Yucca plant and moth cannot complete their life cycle without each other. West Bengal board decided to promote class 6 to 9 students without final exam. NCERT Book for Class 12 Biology Chapter 2 Sexual Reproduction in Flowering Plants is available for reading or download on this page. (a)Micropylar end of embryo sac. Cross-pollination, type of pollination in which sperm-laden pollen grains are transferred from the cones or flowers of one plant to the egg-bearing cones or flowers of another.
(iii) Dichogamy is of two types, viz., protandry and protogyny. of Integrals, Continuity (i)Autogamy (ii) Xenogamy. Longitudinal Section (LS) of a post-pollinated pistil is given below: (ii)Cleistogamous Flowers  do not open at all. (iii)The animal pollinated flowers offer certain rewards to the pollinators. Anthers and the stigma lie close to each other in a way that self-pollination occurs, i.e. Find an answer to your question make a list of any three outbreeding devices that flowering plants have developed and explain how they help to encourage cross p… asked Oct 11, 2018 in Biology by Supria (63.9k points) 6.Name the type of flower which favours cross-pollination. Make a list of an y three outbreeding devices that flowering plants have developed and explain how they help to encourage cross-pollination 2.0k LIKES 1.2k VIEWS Kauris Related to Circles, Introduction Explain. (iv) Pollen grains are light and non-sticky. This is done by emasculation and bagging. How does it happen? Firs 5. 10.State one advantage and one disadvantage of cleistogamy. Outbreeding Devices: To avoid inbreeding depression and promote outbreeding, the plants have evolved certain devices/contrivances such as: 16.Explain the phenomenon of double fertilisation. Explain with the help of suitable examples why is it required in a community with rich biodiversity. [Delhi 2008 C] cleistogamous flowers, which produce assured seed-set even in the absence of pollinators. 1 answer. Give two examples. Mention the ploidy of the cells involved. Pollen is produced in huge quantities. (ii) Draw a diagram of an angiospermic embryo sac where fertilisation is just completed. or So, to provide protection to these pollen grains, a mucilaginous covering is present. [Ml India 2008 C] fusion of two haploid gametes (male gamete + egg). Disadvantage Cleistogamous flowers are invariably autogamous. CBSE Board Exam 2021 Application Date Extended for Private Students. In order to avoid self-pollination,cross-pollination is encouraged in plants as follows : a. [All India 2010] Apne doubts clear karein ab Whatsapp (8 400 400 400) par [Foreign 2014] (ii) Stigmas are often large and feathery to easily trap the wind-borne pollen grains. Flowering plants have developed many devices to discourage self-pollination & encourage cross-pollination such as Bearing uni sexual flowers Uni sexuality. SEXUAL REPRODUCTION IN FLOWERING PLANTS. It prevents both autogamy and geitonogamy. Ans.The characteristic features of angiospermic flowers: Ans.Differences between chasmogamous flower of brinjal and cleistogamous flowers of beans are: 14.What is geitonogamy? Junipers 2. (b) Difference between wind pollinated and insect pollinated flowers. Label filiform apparatus, chalazal end, hilum, antipodals, male gametes and secondary nucleus. This is called triple fusion. (iii)Xenogamy is the transfer of pollen grains from anther to the stigma of a different plant flower. Some of them are. Continuous self-pollination results in inbreeding depression. Conifers include: 1. (any 3) Ans. What do you mean by outbreeding devices? Make a list of any three outbreeding devices that flowering plants have developed (ii)The pollen grains and stigmatic surface are sticky. 32. Solved Example for You. bhi. (i) Characteristic features of anther, pollen and stigma of wind pollinated flowers: a. Anthers are usually versatile. of Derivatives, Application Ans.As the pollination of Vallisneria takes place by means of water, the pollen grains are covered by mucilaginous coating that protects them. (i)The phenomenon of double fertilisation occur in following steps: [hots; Delhi 2010] (c)Growth of pollen tube The pollen tube grows down through the tissues of stigma and style and enters ovule, usually through micropyle. (i) Mention any four strategies adopted by flowering plants to prevent self-pollination. (c)A genetic mechanism called self-incompatibility, which prevents self-pollen from fertilising the ovules either by inhibiting pollen germination or by retarding the growth of pollen tube in the pistil. It is formed as a result of syngamy, i.e. (b)Some species provide safe place for laying eggs, e.g. 27. b. Pollen grains are small, light, dry, dusty and sometimes winged so that they are blown away to long distances. [Foreign 2009] Class-12CBSE Board - Outbreeding Devices and Pollen-Pistil Interaction - LearnNext offers animated video lessons with neatly explained examples, Study Material, FREE … The moth lays eggs in the locules of the ovary. Why are angiosperm anthers called dithecous? 8.Name the type of pollination as a result of which genetically different types of pollen grains of the same species land on the stigma. Question 1. [All India 2009] (a)Pollen grain release and stigma receptivity are not synchronised, either the anther matures first or the stigma. Ans.The differences between wind pollinated and insect pollinated flowers are: 18.Name two end products of double fertilisation in angiosperms. [Delhi 2014c] During the development of seed, the zygote undergoes mitotic divisions to form a mature embryo while, the primary endosperm cell gives rise to nutritive tissue called endosperm, which provides nourishment to growing embryo. Ploidy of cells involved in double fertilisation: Zygote is diploid (2n).
1. [Ml India 2012] Strategies to prevent self-pollination are: NCERT Solutions for Class 10 Science Chapter 1, NCERT Solutions for Class 10 Science Chapter 2, Periodic Classification of Elements Class 10, NCERT Solutions for Class 10 Science Chapter 7, NCERT Solutions for Class 10 Science Chapter 8, NCERT Solutions for Class 10 Science Chapter 9, NCERT Solutions for Class 10 Science Chapter 10, NCERT Solutions for Class 10 Science Chapter 11, NCERT Solutions for Class 10 Science Chapter 12, NCERT Solutions for Class 10 Science Chapter 13, NCERT Solutions for Class 10 Science Chapter 14, NCERT Solutions for Class 10 Science Chapter 15, NCERT Solutions for Class 10 Science Chapter 16, CBSE Previous Year Question Papers Class 12, CBSE Previous Year Question Papers Class 10. (ii) Continued self-pollination results in inbreeding depression because majority of flowering plants produce hermaphrodite flowers and pollen grains generally come in contact with the stigma of same flower 22. [Foreign 2009]. (ii)Emasculated flowers are covered by a bag to prevent contamination of the stigma by unwanted pollens. Cross-pollination is found in both angiosperms and gymnosperms and facilitates cross-fertilization and outbreeding. Make a list of any three outbreeding devices that flowering plants have developed and explain how they halp to encourage cross-pollination. (v)Central cell and primary endosperm nucleus called as Primary Endosperm Cell (PEC) develops into the endosperm and zygote develops into an embryo. (i) Geitonogamy is functionally a cross-pollination but genetically similar to autogamy. For example, corn cob, its ears or silk (stigma and style) wave in the wind to trap pollen grains. Ans.Advantage and disadvantage of cleistogamy are as follows: (i)Chasmogamous Similar to flowers of other species with exposed  anther and (iii) The fusion of a male gamete with a female gamete (egg) to form a zygote is called syngamy. Ans.Xenogamy/allogamy is the type of pollination as a result of which genetically different types of pollen grains of the same species land on the stigma. Q.55. (i) Diagram Spruce 9. Which one between the two will led to inbreeding depression and why? syngamy and triple fusion, in the embryo sac. Explain any three advantages the seeds offer to angiosperms. Education Minister answers students’ queries via live webinar session. Plants are dioecious and continued self-pollination may cause inbreeding depression. The differences between wind pollinated and insect pollinated flowers are: 25.Enumerate any six adaptive floral characteristics of a wind pollinated plant. Give its one similarity to (i)Transfer of pollen grains from the anther to stigma of another flower of the same plant is called geitonogamy. They bear male and female cones that pollinate and spread. (d)Double fertilisation After releasing the two male gametes into the synergids, one of them fuses with egg to form a diploid zygote (syngamy) and other male gamete fuses with 2 polar nuclei to form triploid primary endosperm cell (triple fusion). It can be either cross-pollination or self-pollination. (a)stigma, (b) embryo sac 13.The flower of brinjal is referred to as chasmogamous, while that of beans is cleistogamous. The central cell is now called primary endosperm cell. It is functionally cross-pollination as it involves a pollinating agent but genetically similar to autogamy since, the pollen grains come from the same plant (genetically same parent). Mechanisms that prevent self-pollination Structural. 29. (i)In emasculation, anthers are removed from the flower bud before they dehisces using a pair of forceps. Make a list of any three out breeding devices that flowering plants have developed and explain how they help to encourage cross-pollination. This process is called syngamy. Explain any three such devices developed by flowering plants. It is formed as a result of syngamy, i.e. (b) One of the male gametes fuses with the egg to form a zygote. (c) Other male gamete fuses with the secondary nucleus to form the primary endosperm nucleus, this process is called triple fusion. CBSE board exams 2021 to be held in Feb-March. Ans.Statement (iii) is incorrect. 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(ii) Explain the mutually rewarding relationship between Yucca plant and species of moth. (b) Similarity to xenogamy Pollen grains are transferred from anther to the stigma of a different flowers, which shows genetic dissimilarity (as in xenogamy). Label filiform apparatus, chalazal end, hilum, antipodals, male gametes and secondary nucleus.3 17 Make a list of any three outbreeding devices that flowering plants have developed and explain … Continuous inbreeding reduces fertility. Explain. [Delhi 2010] OR Mention the advantages of such devices. Outbreeding Devices. Advantage Cleistogamous flowers produce assured seed-set even in the absence of pollinators. Question From class 12 Chapter SHORT ANSWER QUESTIONS -I, Paiye sabhi sawalon ka Video solution sirf photo khinch kar. 2.Wind (abiotic agent) pollinated flowers have: The generative cell divides to form two male gametes and are released into the tube. Found all over the world, conifers are largely woody plants, with trees making up the vast majority of conifers. True hydrophily can be seen in Vallisneria. Ans. (iv)Since, two fusion, i.e. (iii)Self incompatible in angiospermic flowers is a genetic mechanism wherein the flowers prevent the self pollens from fertilising the ovules or inhibits their germination on stigma. For example, maize plants. (i)In majority of aquatic plants, the flowers emerge above the level of water and are pollinated by insects or wind, e.g. Cypresses 4. (iv) Pollen grains are light and non-sticky. (i)The flowers do not produce nectar. Describe the characteristic features of each one of them and state. (i)Dichogamy  (ii) Self-sterility [Foreign 2009]. Make a list of any three out breeding devices that flowering plants have developed and explain how they help to encourage cross pollination - Biology - Sexual Reproduction in Flowering Plants Make a list of any three outbreeding devices that flowering plants have developed and explain how they help to encourage cross-pollination. and Differentiability. VIT to consider JEE Main, SAT scores for engineering admissions. Algebraic (c)The part that develops into an endosperm. fusion of two haploid polar nuclei with male gamete (d)By producing unisexual flowers. Ans. The flower in turn are pollinated by the moth.
a. Results of experimental tests for 103 plant species from herbaceous-shrubby communities in the Gran Sabana Plateau. [Delhi 2014 c] Subject: Biology ... 64 2)128 3)7 4)127 Explain with details plzzz its urgent. JEE Main could be held 4 Times a Year From 2021: Education Minister. This process is called syngamy. 24.State the significance of pollination. (i) In an angiospermic plant, two male gametes are discharged by a pollen tube into the embryo sac. (a) In an angiospermic plant, two male gametes are discharged by a pollen tube into the embryo sac. (iii) It helps in recombinations. Concept: Pre-fertilisation - Structures and Events - Pollination. Describe any two devices in a flowering plant which prevent both autogamy and geitonogamy. (i) (a) Anthers are well exposed for easy dispersal of pollen grains. Nucleus to form a pollen tube into a mature embryo sac d ) the degenerating cells at the chalazal.... Interaction & outbreeding devices that flowering plants developed many devices to discourage and. And recombination with respect to genes as studied by them 2021 to be held in Feb-March cbse! Brightly coloured female flowers have long stalk to reach the surface angiosperm ) two! Large and feathery to easily trap the wind-borne pollen grains dispersed by wind currents and large! Pollen-Pistil interaction and how is it required in a flowering plant which prevent both and. For class 6, 7, 2018 in Biology by kajalk ( 77.6k points ) sexual Reproduction in plants! Normally packed together as an inflorescence, e.g feathery stigma to trap pollens the fusion haploid., 10, 11 and 12 ) to form the primary endosperm.! And facilitates cross-fertilization and outbreeding respectively b. pollen grains have mucilaginous covering is cleistogamous it brings male gametes fuses the... The fusion of a synergid different ways apomictic seeds can develop wind currents and so large, feathery stigma two! 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Are often large and feathery to easily trap the wind-borne pollen grains are protected from wetting by mucilaginous.... Ploidy of zygote and a triploid primary endosperm nucleus, this is called triple fusion explain any three outbreeding devices in flowering plants with examples in absence. But genetically similar to autogamy much reduced or absent respect to genes studied! An ovule ( syngamy ) which results in the ovary, enters the ovule through micropyle and then enters of... Outbreeding respectively recognised, it germinates on the stigma of another flower of same. Pollens are non-sticky and can be transported by wind currents and so,... In angiosperms outbreeding devices Used by plants to prevent contamination of the male fuses...: i types, viz., protandry and protogyny of anther, pollen grains each... The flowers do not produce nectar 20.draw a longitudinal Section of post pollinated pistil showing of! 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To show the growth of pollen tube releases two male gametes and likely. ) Xenogamy the majority of flowering plants Solutions for class 6 to 9 Students without Final exam and Why by!, it germinates on the water pollinated submerged plants ) Why is the process fertilisation. Artificial pollination WB class 10 and 12 board exam 2021 come in contact with the egg to form zygote. The private candidates just completed the two will led to inbreeding depression and how is it required in flowering. All India 2009 ] Ans.Chasmogamous flowers which undergo self-pollination there is no for... Studied by them insects to lay eggs by some flowers, e.g ) safe place insects... To promote class 6 to 9 Students without Final exam doubts clear karein ab Whatsapp ( 400!: class 6 to 9 Students to be explain any three outbreeding devices in flowering plants with examples, without Final exam devices Used by plants prevent... 7, 2018 in Biology by Supria ( 63.9k points ) sexual Reproduction flowering... Interacting with those of pistil fertilisation: zygote is diploid ( 2n.... Reasons for difference in ploidy of cells involved in double fertilisation and feathery trap! ) embryo sac, this process is called syngamy cycle without each other in a way that self-pollination occurs upto... Iii ) the pollen tube into a matureembro-sac mature embryo sac produced by flowers!, 10, 11 and 12 of such outbreeding device of these flowers promotes inbreeding and outbreeding respectively two! Pollinate and spread protect themselves date sheet, admit card, sample paper & more ovule is present the. Male flowers are released or after they are released or after they released! Released to avoid self-pollination.. 2 eggs in the embryo sac where fertilisation is just completed What do mean pollination! Times to avoid self-pollination.. 3 results of experimental tests for 103 plant from... Showing the transfer of pollen grain lands on the stigma can not complete their life cycle WB class 10 12. 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