(d) Honey bees are chief pollinating agents so help in improving the plant yield. Sol. Parthenocarpy can be induced through the application of growth hormones 2. It allows the desirable qualities of two different breeds to be combined and produces high yielding breeds. 16. Outbreeding, also called outcrossing, allogamy, or xenogamy, is the transfer of gametes from one individual to another, genetically different individual. Flowering plants have some devices to prevent self pollination and to promote cross-pollination. Ans. Outbreeding devices : (i) In order to avoid self-pollination, cross-pollination is encouraged in plants as follows: (a) Avoiding synchronization : In some species, pollen release and stigma receptivity are not synchronized. mulberry, papaya). Animals with high yielding potential and those who are resistant to diseases must be selected. Pollen is produced in huge quantities. Delhi - 110058. 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. 1. Outbreeding Devices or Contrivances to Ensure Cross Pollination: (i) Dicliny (Uni-sexuality): Flowers are unisexual so that self pollination is not possible. Good quality as well as quantity of food for cattle must be provided. mulberry, papaya). 5. Herkogamy: Flowers possess some mechanical barrier on their stigmatic surface to avoid self-pollination.. 2. 9.State one advantage and one disadvantage of cleistogamy. maize) or dioecious bearing male and female flowers on individual plants (e.g. Not surprisingly, many species of plants have developed mechanisms that prevent self-pollination. These are as follows : (b) Outbreeding which may be done by outcrossing ,cross breeding or interspecific hydridization. (c) Another product called beeswax is also produced which is used in cosmetic and polish industry. The pistil is the female reproductive part of a flowering plant comprising of the ovary, style, and stigma. Out of these methods, cross breeding is the best method of animal breeding because it is breeding between the superior males of one breed are mated with superior females of another breed. stigma becomes receptive much before pollens are released or after they are released to avoid self-pollination. (ii) Prepotency: Pollen grains of another flower germinate more rapidly over the stigma than the pollen grains of the same flower. Q.45. Outbreeding Devices-Continued self-pollination result in inbreeding depression. The continued self-pollination leads to chances of inbreeding depression. https://www.zigya.com/share/QklFTjEyMTExNjky. The plants may be monoecious bearing both male and female flowers (e.g. it has made plants outbreeders and this maintain vigour and vitality of the race. In some species, pollen release and stigma receptivity are not at the same time. In some other species, the anther and stigma are placed at different positions so that the pollen cannot come in contact with the stigma of the same flower. The outbreeding devices in flowering plants which encourage crosspollination are. 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 ⦠Explain any two devices by which autogamy is prevented in flowering plants. Answer. Make a list of an y three outbreeding devices that flowering plants have developed and explain how they help to encourage cross-pollination . Explain the simplified model of the carbon cycle in nature. Explain. 3. Question 14: Describe any three potential applications of genetically modified plants. Three outbreeding devices in plants : (i) Difference in maturation time of pollen and stigma or pollen release and stigma receptivity are not synchronised. Hygienic conditions should be maintained in the dairy farm. Explain. Mechanisms that prevent self-pollination Structural. Adequate water supply to cattle should be maintained. List any three devices in plants to discourage self-pollination and to encourage cross-pollination. NCERT Book for Class 12 Biology Chapter 2 Sexual Reproduction in Flowering Plants is available for reading or download on this page. Explain the importance of each. The plants may be monoecious (bearing both male and female flowers, e.g., Maize) or dioecious (bearing male and female flowers on different plants, e.g., Mulberry, Papaya). 1. Advantages of sexual incompatibility: it prevents self pollination. Natural methods. It is therefore not unexpected that insect pollinated plants have often evolved devices to ensure selfing in areas where insects are scarce, for example in the Faroes (Hagerup 195 I). Make a list of any three outbreeding devices that flowering plants have developed and explain how they help to encourage cross-pollination. 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. Better breed not surprisingly, many species of plants have developed mechanisms that prevent self-pollination download the question.: Describe any three outbreeding devices: to avoid inbreeding depression and promote outbreeding,,! Different times to avoid self-pollination.. 3 main product of bee keeping is honey is! Tip where a small opening called the germ pore is organized ⦠mechanisms that prevent self-pollination: 1 to! 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