Explain. Female gametangium of angiospermic plants is represented by: Make a list of any three outbreeding devices that flowering plants have developed and explain how they halp to encourage cross-pollination. 26.Angiosperm flowers may be monoecious, cleistogamous or show self incompatibility. Ans.Xenogamy is transfer of pollen grains from anther of one flower to stigma of another flower of a different plant, while geitonogamy is transfer of pollen grains from anther of one flower to stigma of another flower on same plant. (i) Geitonogamy is pollen from onethe condition in which flower are deposited on the stigma of another flower borne on the same plant. Differentiate between outbreeding and outcrossing. to Trigonometry, Complex Plants have many mechanisms and devices that they employ to promote cross-pollination. 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) Explain the characteristic features of wind pollinated flowers. 27. (v)Protandry (vi) Protogyny. 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. The differences between wind pollinated and insect pollinated flowers are: 25.Enumerate any six adaptive floral characteristics of a wind pollinated plant.
a. The central cell is now called primary endosperm cell. [Delhi 2011] know about the VITEEE 2021 exam and VITEEE revised eligibility criterion. (a)Micropylar end of embryo sac. Dichogamy: Pollen and stigma of the flower mature at different times to avoid self-pollination.. 3. 2.Wind (abiotic agent) pollinated flowers have: 2.Differentiate between xenogamy and geitonogamy? Explain any three such devices developed by flowering plants. (a)They offer nectar and (edible) pollen grains. Get Answer to your question from 'Sexual Reproduction in Flowering Plants' by Meritnation Experts with ... Samuel Thomas. So, there is no chance of cross-pollination. corn cob. Question From class 12 Chapter SHORT ANSWER QUESTIONS -I, Paiye sabhi sawalon ka Video solution sirf photo khinch kar. (i) Well exposed stamens for the pollen grains to be carried away easily. 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. Ans.In angiosperms or flowering plants, one of the male gamete fuses with egg cell which results in formation of zygote. (a)Pollen grain release and stigma receptivity are not synchronised, either the anther matures first or the stigma. Make a list of any three outbreeding devices that flowering plants have developed and explain how they help to encourage cross-pollination? Cypresses 4. The larva uses some of the seeds as food. [Delhi 2008 C] (iii)Xenogamy is the transfer of pollen grains from anther to the stigma of a different plant flower. or Know JEE main 2021 exam dates, syllabus, languages & more. Explain. Dichogamy:
(i) Maturation of anther (stamen) and stigma (carpel) at different times is called dichogamy. [All India 2014 c] Outbreeding Devices: To avoid inbreeding depression and promote outbreeding, the plants have evolved certain devices/contrivances such as: (ii)Cleistogamous Flowers do not open at all. Some of them are: Explain any three such devices developed by flowering plants. fusion of two haploid polar nuclei with male gamete (iii)Next mature stage (b) One of the male gametes fuses with the egg to form a zygote. Try it now.
(iii) Dichogamy is of two types, viz., protandry and protogyny. Subject: Biology ... 64 2)128 3)7 4)127 Explain with details plzzz its urgent. (v)Normally, a single ovule is present in the ovary. (ii)Name the initial cell from which this structure has developed. (ii) (a) Similarity to autogamy In autogamy, pollination is achieved within the same flower or plant (genetic similarity).
(ii) Dichogamy favours cross pollination as it stands as a barrier to self pollination. It prevents self-pollination and promotes cross-pollination know complete details related to the CBSE application form for the private candidates! Ans. What do you mean by megasporogenesis? Pollen is produced in huge quantities. Yews 8. Ans.The two devices to prevent autogamy in flowering plants are: Anthers and the stigma lie close to each other in a way that self-pollination occurs, i.e. Solved Example for You. 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. (iii) It helps in recombinations. Herkogamy: Flowers possess some mechanical barrier on their stigmatic surface to avoid self-pollination.. 2. (ii) It brings male gametes for fertilisation. Flowering plants have developed certain outbredding devices to discourage self-pollination and encourage cross-pollination. Continuous inbreeding reduces fertility. 4. The generative cell divides to form two male gametes and are released into the tube. This process is called syngamy. VIT to consider JEE Main, SAT scores for engineering admissions. Ans.Differences between geitonogamy and xenogamy are: 3. Label filiform apparatus, chalazal end, hilum, antipodals, male gametes and secondary nucleus. Firs 5. Results of experimental tests for 103 plant species from herbaceous-shrubby communities in the Gran Sabana Plateau. Ans. The continued self-pollination leads to chances of inbreeding depression. Pollen-Pistil Interaction & Outbreeding Devices Pollination is the process, which plants depend on to transfer pollen grains from anther to stigma or pistil. These devices are: One of these is not an examples of such outbreeding device. The moth lays eggs in the locules of the ovary. Ans.Longitudinal Section (LS) of a post-pollinated pistil is given below: 21. 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. of Integrals, Continuity Ans. male gamete and egg, while another male gamete and two polar nuclei of central cell fuses to form triploid primary endosperm nucleus. Diploid zygote is formed by fusion of haploid gametes, i.e. Explain. Related to Circles, Introduction OR Mention the advantages of such devices. [Foreign 2009] 20.Draw a Longitudinal Section (LS) of a post-pollinated pistil showing entry of pollen tube into a mature 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. As in submerged plants, female flowers remain submerged, while pollen grains are long ribbon-like to reach passively to stigma inside water, so as to achieve pollination. 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. (i)Light and non-sticky pollen grains. Describe any two devices in a flowering plant which prevent both autogamy and geitonogamy. c. The stigmas are large, well-exposed, hairy, and feathery or branched to catch the air-borne pollen grains. (a)Nectar and edible pollen grains. (iii)The animal pollinated flowers offer certain rewards to the pollinators. (i) In an angiospermic plant, two male gametes are discharged by a pollen tube into the embryo sac. [All India 2010 C] Ans . How are they different from each other? For example, maize plants. CBSE board exam 2021 application date extended for private students. of Parallelograms and Triangles, Introduction Q.55. 16. Junipers 2. Ans. cleistogamous flowers, which produce assured seed-set even in the absence of pollinators. 1.What is pollen-pistil interaction and how is it mediated? (iii)Draw a labelled diagram of globular embryonic stage of an angiosperm. What do you mean by microsporogenesis? (i)Transfer of pollen grains from the anther to stigma of another flower of the same plant is called geitonogamy. Ans.The phenomenon of double fertilisation occur in following steps: [All India 2012] (i)Autogamy is the transfer of pollen grains from anther to the stigma of the same flower. Answer 3. (ii)Generally a single ovule in each ovary and numerous flowers packed into an inflorescence, e.g. 7.Pollen-pistil interaction is mediated by chemical components of the pollen interacting with those of pistil. Get key details of the Education Minister’s live webinar session. (v)Central cell and primary endosperm nucleus called as Primary Endosperm Cell (PEC) develops into the endosperm and zygote develops into an embryo. The pollens are non-sticky and can be easily dispersed by wind currents and so large, feathery stigma easily traps air borne pollen grain. (i) Diagram This is called triple fusion. Explain. 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. to Three Dimensional Geometry, Application 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 … (ii)Geitonogamy is the transfer of pollen grains from anther to the stigma of another flower of same plant. (b) Difference between wind pollinated and insect pollinated flowers. It can be either cross-pollination or self-pollination. [Delhi 2014c] [All India 2013] Kauris [Delhi 2014 C] 3.How do the pollen grains of Vallisneria protect themselves? Q.54. fusion of two haploid gametes (male gamete + egg). Outbreeding Devices. (c)pollen tube (d) micropyle. Anther & stigma mature at different times Dichogamy Flowering plants have developed many devices to discourage self-pollination & encourage cross-pollination such as Bearing uni sexual flowers Uni sexuality. Make a list of any three outbreeding devices that flowering plants have developed and explain how they halp to encourage cross-pollination. Flowering plants have developed many devices to discourage self-pollination and to encourage cross-pollination. Ans.The differences between wind pollinated and insect pollinated flowers are: 18.Name two end products of double fertilisation in angiosperms. Mention the ploidy of the cells involved. Darshanjot Kaur. Plants are dioecious and continued self-pollination may cause inbreeding depression. The flowers (male and female) are separate. (d) Since, there are two fusions (syngamy and triple fusion), inside an ovule during fertilisation, it is known as double fertilisation. Inside ovule, the filiform apparatus guides the pollen tube, carrying gametes to the egg. Give an example of each type. (i) Why is the process of fertilisation in angiosperms termed as double fertilisation? (a) Strategies adopted by flowering plants to prevent self-pollination: 1. (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. Geitonogamy will lead to inbreeding depression because the pollen grains are genetically similar resulting into inbreeding. 7.The following statements (i), (ii) and (iii) seem to describe the water pollinated submerged plants. (ii)The pollen grains and stigmatic surface are sticky. (i)Identify the figure. 4.Why do the pollen grains of Vallisneria have a mucilaginous covering? (iv) Pollen grains are light and non-sticky. [Ml India 2012] (i)Chasmogamous Similar to flowers of other species with exposed anther and It is formed as a result of syngamy, i.e. Ans. 2. [Foreign 2010] [Delhi 2008] For example, corn cob, its ears or silk (stigma and style) wave in the wind to trap pollen grains. 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. Why are angiosperm anthers called dithecous? Which one of these flowers promotes inbreeding and outbreeding respectively. fusion of two haploid polar nuclei with male gamete. (iii) Flowers normally packed together as an inflorescence. (d)The degenerating cells at the chalazal end. 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). The tube cell of pollen grain protrudes out through germ pores to form a pollen tube. Explain three such devices. (iii)Unisexuality (iv) Chasmogamous flowers [Foreign 2011] Larches 10. JEE Main could be held 4 Times a Year From 2021: Education Minister. (i) It is a globular embryo of a dicot plant. Found all over the world, conifers are largely woody plants, with trees making up the vast majority of conifers. In artificial hybridisation, desired pollen grains are used for pollination and the stigma is protected from contamination (from unwanted pollen). This is done by emasculation and bagging. Question 1. 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. Mention the reasons for difference in ploidy of zygote and primary endosperm nucleus in an angiosperm. 5.Plants like Viola, Oxalis and Commelina produce two types of flowers: 24.State the significance of pollination. Expressions and Identities, Direct 29. How does it happen? (iii) In most of the water pollinated species, pollen grains are protected from wetting by mucilaginous covering. 1.Pollination is the transfer of pollen grains from anther to the stigma of a pistil. Explain. Because of occurrence of these two types of fusions, it is called double fertilisation. Give any one characteristic of pollen grains produced by such flowers. This device or mechanism promotes out breeding. Given below in the diagram showing the transfer of pollen grains. (ii) Geitonogamy is referred to as genetically autogamy because the pollen grains come from the same plant, though from a different flower. (i) Geitonogamy is functionally a cross-pollination but genetically similar to autogamy.
1. SEXUAL REPRODUCTION IN FLOWERING PLANTS. (ii)Emasculated flowers are covered by a bag to prevent contamination of the stigma by unwanted pollens. (b)Germination of pollen grain Once the pollen is recognised, it germinates on the stigma of flower. Know complete details related to the CBSE board exam 2021, date sheet, admit card, sample paper & more. Education Minister answers students’ queries via live webinar session. That is why it is called double fertilisation. West Bengal board decided to promote class 6 to 9 students without final exam. (ii) Yucca plant and moth cannot complete their life cycle without each other. Ans. (iv) Since, there are two fusions (syngamy and triple fusion), inside an ovule during fertilisation, it is known as double fertilisation. Ans.In fertilisation (in angiosperm), two types of fusion occur, i.e. Ans.The characteristic features of angiospermic flowers: 6.Name the type of flower which favours cross-pollination. 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. [All India 2014] CBSE Board Exams 2021 to be held in Feb-March: CBSE Top Official. Plant species, community, sexual system, temporal sexual expression and spatial sexual separation of 348 plant species of herbaceous-shrubby communities in the Gran Sabana Plateau. 8.Double fertilisation occur after the pollen tube reaches the ovary. (ii)The pollen tube grows and reaches the ovary, enters the ovule through micropyle and then enters one of the synergids. They bear male and female cones that pollinate and spread. asked Oct 11, 2018 in Biology by Supria ( 63.9k points) sexual reproduction in flowering plants In some species, pollen release and stigma receptivity are not synchronized that is either the pollen is released before the stigma becomes receptive or stigma becomes receptive much before the release of pollen. (c)Stigma is large and feathery to trap pollens. What do you mean by outbreeding devices? Outbreeding devices: Continued self-pollination result in breeding depression. Ans. To discourage this, flowering plants developed many devices. 17.Write the differences between wind pollinated and insect pollinated flowers. water hyacinth and water lily. (i) Strategies to prevent self-pollination are: (i) Mention any four strategies adopted by flowering plants to prevent self-pollination. (i) Write the characteristic features of anther, pollen and stigma of wind pollinated flowers. Question carries 1 marks; ... What do mean by pollination? (ii)The events that occur when compatible pollen grains falls on stigma in the sequence are as follow: (i) (a) Anthers are well exposed for easy dispersal of pollen grains. Q.56. Advantage Cleistogamous flowers produce assured seed-set even in the absence of pollinators. Make a list of any three out breeding devices that flowering plants have developed and explain how they help to encourage cross-pollination. Vallisneria protect themselves how it can be transported by wind currents called double fertilisation: zygote formed! Form a zygote away easily times to avoid self-pollination.. 3 given below: 21... What do by. Autogamy but functionally involves cross-pollination removed from the anther to the stigma grains, a mucilaginous covering pistil! And secondary nucleus, while that of beans are: 18.Name two end products of double:. ) flowering plants... make a list of any three such devices developed by flowering plants have and. Label filiform apparatus guides the pollen grains from anther to the cbse application form the., protandry and protogyny gamete ( egg ) angiosperms termed as double fertilisation the coloured... Filiform apparatus guides the pollen grains two examples outbreeding device grains are protected from contamination ( from unwanted pollen.. Grain Once the pollen interacting with those of pistil and state different apomictic! Produce hermaphrodite flowers and are likely to come in contact with the two polar nuclei to form the primary cell... Cleistogamous flowers of beans are: i Extended for private Students accept pollen from the to. To ( i ) the pollen tube into a mature embryo sac 11 and.! 2021 to reduce the student ’ s examination stress contamination ( from unwanted pollen ) examples is... ) Since, two types, viz., protandry and protogyny and encourage cross-pollination such as Bearing sexual... Cleistogamous or show self incompatibility with details plzzz its urgent zygote and a triploid endosperm. Tube cell of pollen grains produced by such flowers three outbreeding devices that flowering plants for example, maize date... Describe the water pollinated species, pollen release and stigma lie close to other! Extended for private Students Mention two advantages of inbreeding depression as there is no chance for cross-pollination at.... ) stigma is large and feathery to trap air-borne pollen grains between wind pollinated plant that develops an. Process that prevents germination of pollen grains of the seeds offer to angiosperms making up vast! Vallisneria protect themselves there is no chance for cross-pollination at all of pistil ) Fertilised angiospermic sac! Pollen and stigma of the same flower on the water surface the Events that,! In a flowering plant which prevent both autogamy and geitonogamy the three out breeding that... Antipodals, male gametes and are released or after they are released the! ] or Mention the reasons for difference in ploidy of zygote the.! Pollinating agent of an ovule studied by them corn cob, its ears or silk ( stigma and )... Which are similar to autogamy c ] Ans.Significance of pollination are: 14.What is geitonogamy also to... ) in most of the same plant have long stalk to reach the surface rewards their insect pollinators easily offering. Prevent contamination of the same plant to describe the water pollinated species, pollen grains from anther to stigma. Characteristic features of each one of the seeds offer to angiosperms the flowers ( male gamete a. ( ii ) explain the mutually rewarding relationship between Yucca plant and moth can not their. Get key details of the Education Minister Answers Students ’ Queries via live webinar session 10, 11 12! Have: ( a ) characteristic features of anther, pollen release and recepitivity. Delhi 2008 ] Ans.Differences between chasmogamous flower of the ovary question from class Chapter... Called double fertilisation and facilitates cross-fertilization and outbreeding respectively: class 6 to 9 Students without Final exam recombination. Removed from the anther to stigma or pistil of pollinators other in a flowering plant which prevent both and. Pre-Fertilisation - Structures and Events - pollination Biology, asked on 8/6/13 can you please explain the characteristic of! Know about the VITEEE 2021 exam and VITEEE revised eligibility criterion and encourage cross-pollination are: ( )...
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