71.Name all the haploid cells present in an unfertilized mature embryo sac of a flowering plant. Write the total number of cells in it.
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72.
Draw labelled structures of some selected seeds.
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73.Banana is a parthenocarpic fruit whereas oranges show polyembryony. How are they different from each other with respect to seeds ?
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74.
What are the various adaptations in angiospermic flowers which favour cross-pollination ? Or Explain adaptations by which autogamy is prevented in flowering plants.
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75.
With a neat labelled diagram, describe the parts of a typical angiosperm ovule.
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76.Draw a longitudinal section of a post-pollinated pistil showing entry of pollen tube into a mature embryo sac. Label filiform apparatus, chalazal end, hilum, antipodals, male gametes and secondary nucleus
77. Describe the structure of a typical monosporic embryo sac found in flowering plant.
The single functional mother cell gives rise to female gametophyte or the embryo sac. since only one cell is involved out of four it is called monosporic embryo sac. It divides to form a 8 nucleate and 7 celled embryo sac. the 8 cells that are present are 3 cells that is 1 egg cell and 2 synergids are present at the micropylar end. the synergids and the egg cell together form the egg aparatus. synergids have a speial thickening called filiform apparatus which helps guide the pollen tube into the ovary. @ cells are present at the chalazal end and are called antipodal cells. Three cells are present in the central space and are called polar nuclei.
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78.What do you mean by development of embryo? Support the answer with diagram.
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79.
Describe apomixis , parthenocarpy and polyembryony
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80.Explain the germination of pollen grain with the help of a diagram.
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