2.Wind (abiotic agent) pollinated flowers have: Explain the correlation between linkage and recombination with respect to genes as studied by them. (i)In emasculation, anthers are removed from the flower bud before they dehisces using a pair of forceps. (i) Geitonogamy is pollen from onethe condition in which flower are deposited on the stigma of another flower borne on the same plant. [Foreign 2009] The flower in turn are pollinated by the moth. CBSE Board Exams 2021 to be held in Feb-March: CBSE Top Official. 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. Because of occurrence of these two types of fusions, it is called double fertilisation. 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. (iii) Production of unisexual flowers so that male and female parts will be present on different plants (dioecious) or on different flowers in same plant (monoecious). Ans. 13.The flower of brinjal is referred to as chasmogamous, while that of beans is cleistogamous. 1.What is pollen-pistil interaction and how is it mediated? 18/9/12. Ans.Significance of pollination are: [Foreign 2014] Write their fate during the development of seed. Ans.The two devices to prevent autogamy in flowering plants are: Know complete details related to the CBSE board exam 2021, date sheet, admit card, sample paper & more. 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. The differences between wind pollinated and insect pollinated flowers are: 25.Enumerate any six adaptive floral characteristics of a wind pollinated plant. The generative cell divides to form two male gametes and are released into the tube. (iii) Other male gamete fuses with the secondary nucleus to form the primary endosperm nucleus, this process is called triple fusion. How are they formed? Ans. Some of them are. (c ) Mention two advantages of inbreeding programme in cattle. Advantage Cleistogamous flowers produce assured seed-set even in the absence of pollinators. (ii) Why do flowering plants need to develop outbreeding devices? 19.Differentiate between geitonogamy and xenogamy in plants. [All India 2013] (iii)The brightly coloured female flowers have long stalk to reach the surface. (i)Monoecious flower are unisexual,i.e.they have either the male reproductive or female reproductive part in separate flowers, both produced on same plant. 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 [All India 2009] Junipers 2. (a) Explain the different ways apomictic seeds can develop. 4. (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. It prevents both autogamy and geitonogamy. Explain. (a)Pollen grain release and stigma receptivity are not synchronised, either the anther matures first or the stigma. Explain any three advantages the seeds offer to angiosperms. (ii) Self-incompatibility, a genetic mechanism to prevent pollens from fertilising ovules of same flower by inhibiting their germination on stigma or pistil. [Delhi 2014 C] (d)By producing unisexual flowers. ... Make a list of any three outbreeding devices that flowering plants have developed and explain how they help to encourage cross-pollination. (ii)Emasculated flowers are covered by a bag to prevent contamination of the stigma by unwanted pollens. (c) Other male gamete fuses with the secondary nucleus to form the primary endosperm nucleus, this process is called triple fusion. (b) Similarity to xenogamy Pollen grains are transferred from anther to the stigma of a different flowers, which shows genetic dissimilarity (as in xenogamy). fusion of two haploid polar nuclei with male gamete. Explain. Larches 10. corn cob. 3.How do the pollen grains of Vallisneria protect themselves?
a. (a)Micropylar end of embryo sac. (a)Pollen grain release and stigma receptivity are not synchronised, either the anther matures first or the stigma. [Delhi 2009] How does it happen? (d)The degenerating cells at the chalazal end. (v)Protandry       (vi) Protogyny. (ii)How do flowers reward their insect pollinator? It is formed as a result of syngamy, i.e. (i) In an angiospermic plant, two male gametes are discharged by a pollen tube into the embryo sac. (iv)Common in grass, maize, date palm, etc. 17.Write the differences between wind pollinated and insect pollinated flowers. (ii)One of the male gamete fuses with egg cell (syngamy) which results in the formation of zygote. (vi)Non-essential whorls, calyx and corolla are much reduced or absent. syngamy and triple fusion occur in an embryo sac, this is called double fertilisation. Make a list of any three outbreeding devices that flowering plants have developed (v)Central cell and primary endosperm nucleus called as Primary Endosperm Cell (PEC) develops into the endosperm and zygote develops into an embryo. Ans. Cross-pollination is found in both angiosperms and gymnosperms and facilitates cross-fertilization and outbreeding. So, zygote is diploid.While primary endosperm cell is triploid because the nucleus of the second male gamete fuses with the two haploid polar nuclei or diploid secondary nucleus of the central cell to form a triploid primary endosperm nucleus. Explain. (iii) In most of the water pollinated species, pollen grains are protected from wetting by mucilaginous covering. The flowering plants, also known as Angiospermae (/ ˌ æ n dʒ i oʊ ˈ s p ɜːr m iː /), or Magnoliophyta (/ m æ ɡ ˌ n oʊ l i ˈ ɒ f ɪ t ə,-oʊ f aɪ t ə /), are the most diverse group of land plants, with 64 orders, 416 families, approximately 13,000 known genera and 300,000 known species. To discourage this, flowering plants developed many devices. (ii)The pollen tube grows and reaches the ovary, enters the ovule through micropyle and then enters one of the synergids. 4.Biotic agents of pollination are insects, animals, etc. 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. Ans.As the pollination of Vallisneria takes place by means of water, the pollen grains are covered by mucilaginous coating that protects them. Pines 6. 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. (ii)Cleistogamous Flowers  do not open at all. 4.Why do the pollen grains of Vallisneria have a mucilaginous covering? (i) Characteristic features of anther, pollen and stigma of wind pollinated flowers: a. Anthers are usually versatile. 20.Draw a Longitudinal Section (LS) of a post-pollinated pistil showing entry of pollen tube into a mature embryo sac. One of these is not an examples of such outbreeding device. 7.Pollen-pistil interaction is mediated by chemical components of the pollen interacting with those of pistil. It is genetically similar to autogamy but functionally involves cross-pollination. Ans.The pollinating agent in the described inflorescence with small dull coloured flowers having well exposed stamens and large stigma is wind. So, to provide protection to these pollen grains, a mucilaginous covering is present. Get Answer to your question from 'Sexual Reproduction in Flowering Plants' by Meritnation Experts with ... Samuel Thomas. In fertilisation (in angiosperm), two types of fusion occur, i.e. Make a list of outbreeding devices that flowering plants have developed and explain how they help to encourage cross-pollination. Numbers and Quadratic Equations, Introduction (b)Anther and stigma are placed at different positions, so that the pollens cannot come in contact with the stigma of same flower.
(iii) Dichogamy is of two types, viz., protandry and protogyny. 10.State one advantage and one disadvantage of cleistogamy. NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12. (a) Strategies adopted by flowering plants to prevent self-pollination: 1. Conifers include: 1. (iv) Since, there are two fusions (syngamy and triple fusion), inside an ovule during fertilisation, it is known as double fertilisation. (b)Anther and stigma are placed at different positions, so that the pollens cannot come in contact with the stigma of same flower. c. The stigmas are large, well-exposed, hairy, and feathery or branched to catch the air-borne pollen grains. (ii) Pollen-pistil interaction is mediated by interaction between chemical components secreted by pollen and those of pistil. (ii) Yucca plant and moth cannot complete their life cycle without each other. (i) Mention any four strategies adopted by flowering plants to prevent self-pollination. 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. 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
1. (i) Draw a labelled diagram of LS of a flower to show the growth of pollen tube reaching egg apparatus. (i)Autogamy is the transfer of pollen grains from anther to the stigma of the same flower. 8.Double fertilisation occur after the pollen tube reaches the ovary. Solved Example for You. Continuous self-pollination results in inbreeding depression. Flowering plants have developed many devices to discourage self-pollination and to encourage cross-pollination. Make a list of any three out breeding devices that flowering plants have developed and explain how they help to encourage cross-pollination. (i)Identify the figure. of Derivatives, Application Answer 3. Describe each one with the help of an example. (iii)Next mature stage Redwoods 7. What do you mean by megasporogenesis? (ii) Explain the mutually rewarding relationship between Yucca plant and species of moth. Describe the structure of its microsporangium. This process is called syngamy. (MARCH-2010) (iv)Since, two fusion, i.e. Continuous inbreeding reduces fertility. Because the majority of flowering plants produce hermaphrodite flowers and are likely to come in contact with the stigma of the same flower. (iii)What is syngamy? Question carries 3 marks; Draw and label a diagram of an ovule. [All India 2010 C] Ans . Kauris Kerala State Board New Syllabus Plus Two Botany Chapter Wise Previous Questions and Answers Chapter 2 Sexual Reproduction in Flowering Plants. [Delhi 2014] bhi. Subject: Biology ... 64 2)128 3)7 4)127 Explain with details plzzz its urgent. 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 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. In artificial hybridisation, desired pollen grains are used for pollination and the stigma is protected from contamination (from unwanted pollen). Water (abiotic agent) pollination occurs in mostly monocotyledons (in about 30 genera). 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. Some of them are: (i) (a) Characteristic features of wind pollinated flowers. In some species, pollen release and stigma recepitivity are not synchronized. Related to Circles, Introduction These flowers are invariably autogamous and promotes inbreeding depression as there is no chance for cross-pollination at all. (i)Light and non-sticky pollen grains. 1 answer. Make a list of any three outbreeding devices that flowering plants have developed and explain how they help to encourage cross-pollination. (a) List the three states the annuals and biennial angiosperms have to pass through during their life cycle. 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. (ii) Stigmas are often large and feathery to easily trap the wind-borne pollen grains. (iv) Pollen grains are light and non-sticky. (ii)Fertilised angiospermic embryo sac with label is given below: 30. Question carries 1 marks; ... What do mean by pollination? cleistogamous flowers, which produce assured seed-set even in the absence of pollinators. (i)In majority of aquatic plants, the flowers emerge above the level of water and are pollinated by insects or wind, e.g. (iv) Pollen grains are light and non-sticky. (i)Chasmogamous Similar to flowers of other species with exposed  anther and Ans.Floral characteristics of a wind pollinated plant are: 31. Ans.In wind pollinated flowers: and Inverse Proportions, Areas (iii)The animal pollinated flowers offer certain rewards to the pollinators. (vi)Non-essential whorls, calyx and corolla are much reduced or absent. Give two examples. [Delhi 2008 C] Which one between the two will led to inbreeding depression and why? This process is called syngamy. Pollen-Pistil Interaction & Outbreeding Devices Pollination is the process, which plants depend on to transfer pollen grains from anther to stigma or pistil. (v)Normally, a single ovule is present in the ovary. VIT to Consider JEE Main, SAT Scores for Engineering Admissions. [Foreign 2014] (iii) Well exposed stamens and large feathery stigma to trap air-borne pollen grains. Describe any two devices in a flowering plant which prevent both autogamy and geitonogamy. Question 24: Define the following terms: Lactation. (ii) Self-incompatibility is a genetic process that prevents germination of pollen from the same flower on the stigma. Inside ovule, the filiform apparatus guides the pollen tube, carrying gametes to the egg. Ans.Longitudinal Section (LS) of a post-pollinated pistil is given below: 21. (ii)The female flower reach the surface of water by the long stalk and pollen grains are released on to the surface of water, e.g. The flowers (male and female) are separate. [All India 2009] (iii)Unisexuality  (iv) Chasmogamous flowers Pollen-pistil interaction is a chain or group of events that takes place from the falling of pollen over the stigma to the formation of pollen tube and its entry into the ovule. (c)The part that develops into an endosperm. 5.Mention the pollinating agent of an inflorescence of small dull coloured flowers with well exposed stamens and large feathery stigma. (i) Well exposed stamens for the pollen grains to be carried away easily. 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. (i) Geitonogamy is functionally a cross-pollination but genetically similar to autogamy. Education Minister answers students’ queries via live webinar session. 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). (ii) One of the male gametes fuses with the egg to form a zygote. Mention the reasons for difference in ploidy of zygote and primary endosperm nucleus in an angiosperm. Ploidy of cells involved in double fertilisation: Zygote is diploid (2n). For example, corn cob, its ears or silk (stigma and style) wave in the wind to trap pollen grains. [Foreign 2011] Ans.Differences between chasmogamous flower of brinjal and cleistogamous flowers of beans are: 14.What is geitonogamy? 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