How does it happen? Algebraic 1.Pollination is the transfer of pollen grains from anther to the stigma of a pistil. Firs 5. 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 Outbreeding devices: Continued self-pollination result in breeding depression. (v)Central cell and primary endosperm nucleus called as Primary Endosperm Cell (PEC) develops into the endosperm and zygote develops into an embryo. Flowering plants have developed certain outbredding devices to discourage self-pollination and encourage cross-pollination. [Foreign 2011] 11.Why should a bisexual flower be emasculated and bagged prior to artificial pollination? (ii)How do flowers reward their insect pollinator? 4. Herkogamy: Flowers possess some mechanical barrier on their stigmatic surface to avoid self-pollination.. 2. Make a list of any three out breeding devices that flowering plants have developed and explain how they help to encourage cross-pollination. Question carries 1 marks; ... What do mean by pollination? This process is called bagging. (iv)Since, two fusion, i.e. One of these is not an examples of such outbreeding device.
a. 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. (vi)Non-essential whorls, calyx and corolla are much reduced or absent. What do you mean by outbreeding devices? [Ml India 2012] Mention the ploidy of the cells involved. The flower in turn are pollinated by the moth. Expressions and Identities, Direct Explain. (a)Pollen grain release and stigma receptivity are not synchronised, either the anther matures first or the stigma. (i) Mention any four strategies adopted by flowering plants to prevent self-pollination. (iii) Flowers normally packed together as an inflorescence. The pollens are non-sticky and can be easily dispersed by wind currents and so large, feathery stigma easily traps air borne pollen grain. Ans.Longitudinal Section (LS) of a post-pollinated pistil is given below: 21. Give an example of each type. [All India 2014] [All India 2013] (iv) Pollen grains are light and non-sticky. (i)Following compatible pollination, pollen grain germinates on the stigma to produce a pollen tube through a germ pore. 31. 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. fusion of two haploid polar nuclei with male gamete (b)The part that develops into an embryo. 2.Wind (abiotic agent) pollinated flowers have: Differentiate between outbreeding and outcrossing. Ans.The phenomenon of double fertilisation occur in following steps: Ans.Emasculation in a bisexual flower is required to prevent contamination of the stigma with self pollen grains.Bagging is done to prevent contamination of the stigma of the emasculated flower with any other unwanted pollen grains. 2.Differentiate between xenogamy and geitonogamy? (i) Pollination is a pre-requisite for fertilisation in plants. (b)Anther and stigma are placed at different positions, so that the pollens cannot come in contact with the stigma of same flower. [Delhi 2008 C] (i)Autogamy (ii) Xenogamy. water hyacinth and water lily. asked Oct 11, 2018 in Biology by Supria (63.9k points) (ii) Why do flowering plants need to develop outbreeding devices? This is called triple fusion. (a)Nectar and edible pollen grains. [Delhi 2010] The larva uses some of the seeds as food. Mention the reasons for difference in ploidy of zygote and primary endosperm nucleus in an angiosperm. (ii)The pollen tube grows and reaches the ovary, enters the ovule through micropyle and then enters one of the synergids. (ii)Generally a single ovule in each ovary and numerous flowers packed into an inflorescence, e.g. b. Pollen grains are small, light, dry, dusty and sometimes winged so that they are blown away to long distances. (i) Geitonogamy is pollen from onethe condition in which flower are deposited on the stigma of another flower borne on the same plant. [All India 2012] [Delhi 2011] (i) (a) Anthers are well exposed for easy dispersal of pollen grains. Related to Circles, Introduction For example, corn cob, its ears or silk (stigma and style) wave in the wind to trap pollen grains. (b) Explain inbreeding depression and how it can be overcome. (ii) Self-incompatibility, a genetic mechanism to prevent pollens from fertilising ovules of same flower by inhibiting their germination on stigma or pistil. Write their fate during the development of seed. Ploidy of cells involved in double fertilisation: Zygote is diploid (2n). Mechanisms that prevent self-pollination Structural. syngamy and triple fusion, in the embryo sac. What do you mean by megasporogenesis? Disadvantage Cleistogamous flowers are invariably autogamous. [Foreign 2011] [Delhi 2014 c] Which one of these statements is incorrect? Continuous self-pollination results in inbreeding depression. Some of them are  Strategies to prevent self-pollination are: (iii)Next mature stage Dichogamy:
(i) Maturation of anther (stamen) and stigma (carpel) at different times is called dichogamy. It prevents self-pollination and promotes cross-pollination So, to provide protection to these pollen grains, a mucilaginous covering is present. It is formed as a result of syngamy, i.e. Label Explain any three such devices developed by flowering plants. Cypresses 4. fusion of two haploid polar nuclei with male gamete. Outbreeding Devices: To avoid inbreeding depression and promote outbreeding, the plants have evolved certain devices/contrivances such as: (ii)Pistil of a flower does not accept pollen from any plant other than its own kind. [Foreign 2009] asked Oct 11, 2018 in Biology by Supria ( 63.9k points) 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? The tube cell of pollen grain protrudes out through germ pores to form a pollen tube. 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