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Oogenesis and its process_Physic Chemistry Biology

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 Oogenesis and its process This topic is available on the class 12 Biology book chapter number 3 human reproduction                   5 mark  Board examination question Ans. The process of formation of a mature female gamete is called oogenesis  The process of oogenesis are divided into three categories multiplication phase, growth phase and maturation phase  a). Multiplication phase :-In  this phase the germ cells of the germinal epithelium of the ovary repeatedly divided mitotically to produce a larger numbers of dipole oogonia or egg mother cells.When cell division stops they are called oocyte. b). Growth phase:- in this phase the oocytes increase in size in several time due to accumulation of Yolk.The enlarged oocyte with yolk is known as primary oocyte. c).Maturation face:-The growth phases followed by the maturation phase.During this phase the primary oocyte undergo two successive division called maturation division  The first maturation division is reduction division producing
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Development of male gametophyte_Physic Chemistry Biology

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 Process and development of male gametophyte This topic is available on class 12 biology chapter number 2 sexual reproduction of flowering plant  This topic is 5 mark questions of board examination Ans.  Stamen from the male reproductive unit and is made up of anther and the filament. The anther is generally bilobed with chamber  containing several pollen grains a). Pollen grain are produced in the anther. A vary young antha comprises a mass of undifferentiated thin walled cells bounded by an epidermis. b). The anther becomes four lobed as the anther grows,and the lobes are joined by a steril tissue called connective. c).Each lobe contains an elongated chamber which is termed as microsporogenesis or Pollen sac. d). A cross section of a young anther reveals that the microsporangium is surrounded on the outside by a single layered epidermis.Beneath the epidermis is a layer of cells called the endothecium. e).The sporangial wall encloses a mass of cells characterised by their large size a
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