Out of the six cells, three are grouped at the micropylar end and constitute the egg apparatus made up of two synergids and one egg cell. (b) Gametophyte and sporophyte of Funaria. why is sporopollenin considered the most resistant organic material? [Foreign 2012; All India 2010 C; Delhi 2009] It undergoes meiosis resulting in the production of four megaspores. Thus, 8-nucleated, 7-celled female gametophyte is formed within the functional megaspore; therefore the development is called endospores. While, the innermost layer tapetum is nutritive in function and nourishes the developing pollen grains. c. Alternation of generation in Angiosperm. Total microsporangium = 4 x 100 = 400.So, anther produces 400 male gametes. Female and male thallus of a liverwort. Male Gamete Development The angiosperm reproductive cycle begins with the process of microsporogenesis, or microspore formation. The outer three wall layers perform the function of protection and help in dehiscence of anther to release pollen. 12). Ans. [Delhi 2010] Mention the fuction of each one of them. The nucleus is large and irregular. Draw labelled diagrams of (a) Female and male thallus of a liverwort. Explain. Following is the labelled diagram of a male gametophyte of an angiosperm.Sporopollenin is considered to be the most resistant organic material because it is chemically very stable and it can withstand high temperatures, acidic and alkaline conditions, and enzymes. The pollen tube comes from the tube cell from the male gametophyte. [Delhi 2008] Angiosperm male gametophytes have two haploid nuclei (the germ nucleus and tube nucleus) contained within the exine of the pollen grain (or microspore). Draw labelled diagrams of the following: (a) Female and male thallus of a liverwort. Transformation of microspore mother cell (2n) into pollen grain (n) is the first gametophytic structure. 23.Draw a labelled diagram of the sectional view of a mature pollen grain in angiosperm. Male Gametophyte Explanation: ... 12.02.2020 Biology Secondary School (a) Draw a labelled diagram of the sectional view of microsporangium of an angiosperm. Ans.An unfertilised embryo sac of angiosperm is composed of 7 cells, i.e. Overview. State its significance with reference to its chemical nature. It divides mitotically to form two non-motile male gametes, prior to release of pollen grain. With the development of the seed, the life cycle of Angiosperms comes to a close. c. Alternation of generation in Angiosperm . Name them. b) Why geitonogamy also referred to as genetical autogamy? Draw a well labelled diagram of one microsporangium of anther showing wall layers. Further, mitotic divisions lead to the formation of 4-nucleate and 8-nucleate stages of the embryo sac. (i) Pollen mother cell or microspore mother cell undergoes meiosis to form microspore tetrad or haploid microspores. 5.Megasporogenesis is the process of formation of megaspores from the Megaspore Mother Cell (MMC). 23.Draw a labelled diagram of the sectional view of a mature pollen grain in angiosperm. Therefore the two fusion is called double fertilization. Q.19 How many haploid cells are present in a mature female gametophyte of a flowering plant. The cells of tapetum have dense Ans.The part of the flower that represent the tassels of corn cob are stamens or male reproductive parts. Angiosperms are those seed plants in which seeds are formed inside fruits and the sporophylls are organised into flowers. Further, mitotic divisions lead to the formation of 4-nucleate and 8-nucleate stages of the embryo sac. [Foreign 2014] (iii)Nucleus of the functional megaspore divides mitotically to form two nuclei, which move to the opposite poles forming the 2-nucleate embryo sac. [Foreign 2009] Draw a diagram of a male gametophyte of an angiosperm. (ii)    Each ovule has one or two protective envelopes called integuments. Ans.An anther is a four-sided (tetragonal) structure consisting of four microsporangia located at the corners, two in each lobe. • List key identifying characteristics of the group, interesting/memorable facts about the group, and other key terms associated with the group. Label any four parts. (a) Draw a labelled diagram of the sectional view of microsporangium of an angiosperm. It contains two cells,i.e.vegetative cell and generative cell. Label any four parts. Name them. 2.Draw a diagram of a matured microspore of an angiosperm. A mature pollen grain contains two cells. (iii)Explain the following giving reasons, Ans. Label any four parts. Pollen sacs contain pollen grains. The fourth and innermost layer called the tapetum nourishes developing pollen grains. (c) Alternation of generation in Angiosperm. 20. Q7. calyx (sepals), corolla (petals), androecium and gynoecium. [Delhi 2011] (ii) Why is exine of the pollen grain not a continuous layer? The long and slender stalk called the filament. b) Why geitonogamy also referred to as genetical autogamy? The Life Cycle of an Angiosperm. Q4. (c) Alternation of geneation in angiosperm Sol: The pouch-like structures present in seed plants where pollen is produced. Q4. This is that phase of the plant in which the gametes, that is the egg and sperm formed are haploid (n), having only one set of chromosomes in them. In these mitotic divisions, nuclear division is not followed by cell division. or With the help of a schematic diagram, describe the haplo–diptontic life cycle pattern of a plant group. As with gymnosperms, angiosperms are heterosporous. Answer: Polygonum type embryo sac develops from one functional megaspore. (a) Explain the development of female gametophyte from a megaspore mother cell in an angiosperm. Mature pollen grain comprises of two layers. Q2. (iii) (a) Since, the outer exine layer of pollen grain is highly resistant because of sporopollenin. Draw a well-labelled diagram of Polygonum type of embryo sac. (ii)It is surrounded by four wall layers. Q5. Female gametophytes of flowering plants develop within the ovule (megaspore) contained within an ovary at the base of the pistil of the flower. Answer: Pollen grain is the starting point of male gametophytic generation. (i) Vegetative cell contain food reserves, i.e. Therefore, they generate microspores, which will produce pollen grains as the male gametophytes, and megaspores, which will form an ovule that contains female gametophytes. (C.B.S.E 2010) Q.20 Differentiate between albuminous and non-albuminous seeds, giving one example each. (ix) At the chalazal end, three cells are present called antipodals. On germination pollen grain develops into male gametophyte which starts even before pollination. [Delhi 2009] (i) Draw a schematic diagram of TS of a mature anther. Male gametophyte of an Angiosperms. c. Alternation of generation in Angiosperm. State the function of its innermost wall layer. Explain. So, it fails to produce viable male gametophyte. Label any four parts. Ans.Sporopollenin is present in exine of pollen grains in plants. Syllabus. (a) Draw a schematic labelled diagram of a fertilised embryo sac of an angiosperm. Female and male thallus of a liverwort. Protonema: Spores produced from the moss capsule germinate in favorable conditions. Name them. (2) (a ) Describe the formation of mature female gametophyte within an ovule in angiosperms. It is one of the most resistant organic substances and can withstand high temperatures, strong acids and alkalis. 13.Draw a labelled diagram of a typical anatropous ovule. zygote & the other male gamete fuses with a diploid secondary nucleus to form triploid primary endosperm nucleus (PEN). Draw a labelled diagram of a mature embryo sac. Describe the structure of a mature microsporangium of an angiosperm. Each cell of the tetrad is known as microspore mother cell. The other three cells are located at the chalazal end and are called antipodals. zygote & the other male gamete fuses with a diploid secondary nucleus to form triploid primary endosperm nucleus (PEN). Ans. Draw a labelled diagram to show interrelatonship of four accessory ducts in a human male reproductive system. Megasporangia, commonly called ovules arise from the placenta. How many haploid cells are present in mature female gametophyte of a flowering plant? A diploid cell (megaspore mother cell) in the ovule undergoes meiosis (involving two successive cell divisions) to produce four cells (megaspores) with haploid nuclei. Pollen sacs contain pollen grains. [Delhi 2009] Anther is a bilobed structure with each lobe having two theca, therefore called dithecous. Microsporangium appears circular in outline and is usually surrounded by four wall layers. Explain the functions of its two different parts. (i)The structure of a male gametophyte of an angiosperm is: It involves, two fusions during fertilisation of an ovule. Therefore the two fusion is called double fertilization. (ii)Why does a pollen grain possess two male gametes? The MMC is a large cell with dense cytoplasm and prominent nucleus. Draw a labelled diagram of the two-celled male gametophyte of an angiosperm. The effect of a given sound lasts on a human ear for about 0.1 second.Use this fact along with the knowledge of speed of sound to estimate for getting a clear and a distinct echo? The gametophyte refers to all organs and tissues that are a part of the haploid generation. 5. Answer: Polygonum type embryo sac develops from one functional megaspore. It protect the pollen grains from enzymes and helps them to be well preserved. The outer three layers are epidermis, endothecium and middle layers. Why is sporopollenin considered the most resistant organic material? These are epidermis, endothecium, middle layers and the tapetum. A flower may be monocarpellary (having one pistil) or multicarpellary (having more than one pistils). 2.Stamen is the male reproductive unit of angiosperm. Draw a diagram of a male gametophyte of an angiosperm. 11. No enzyme that degrades sporopollenin is so far known.That’s why it is considered the most resistant organic material. (i) The functional megaspore undergoes mitosis to form two nuclei, which migrate to opposite poles, forming a 2-nucleate embryo sac. State their functions and draw labelled diagrams of both. Following is the labelled diagram of a male gametophyte of an angiosperm.Sporopollenin is considered to be the most resistant organic material because it is chemically very stable and it can withstand high temperatures, acidic and alkaline conditions, and enzymes. Draw a well-labelled diagram of a typical ovule. The process of formation and differentiation of microspore from microspore mother cell by reductional division is known as microsporogenesis. Generally spherical, about 25-50 micrometers in diameter. 5. Draw a well-labelled diagram of a typical ovule. (b) Explain the development of male gametophyte in the microsporangium. 4. • Label the gymnosperm and angiosperm clades on your tree • Label the your tree with the names of 4 extant phyla of gymnosperms and the phylum name for angiosperms. Different stages of development of female gametophyte are given below: Also draw a labelled diagram of embryo sac to explain the phenomena. [Delhi 2009 C] Female and male thallus of a liverwort. ADVERTISEMENTS: The below mentioned article provides a study note on Angiosperms – The Flowering Plants. These synergids possess special cellular thickenings at their micropylar tip which is called filiform apparatus. 21. a. (iv)    Chalaza is opposite to the micropylar end representing the basal part of  the ovule. 6. The adult, or sporophyte, phase is the main phase of an angiosperm’s life cycle. 36869171 000+ Illustrate the stages with labelled diagram. Label … (a)Female and male thallus of a liverwort. NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12. [Foreign 2014] Ans.The labelled diagram of a mature microspore of an angiosperm with its cellular components is given below: 432) we shall find a regular alternation of generations as in most groups of plants. (i)view of TS of one microsporangium of an angiosperm and label the following parts. Draw labelled diagrams of the following: (a) Female and male thallus of a liverwort. Pistils may be syncarpous (fused together) or apocarpous (free). Time Tables. (i)One of the megaspores is functional,  while the other three degenerate in majority of angiosperms. (iii)In unisexual flowers, only either of the reproductive parts are present, e.g. The angiosperm life cycle, in many ways, follows the basic life cycle pattern for land plants (embryophytes), with modifications characteristic of the seed plant habit (read more here).). Overview. Mention the roles of different wall layers of anther. Gametophyte of moss: Gametophyte of moss plant is haploid (n). The plant is a sporophyte with 2n or diploid cells. Diagram. Microsporangia develop and becomes pollen sacs. 21.Draw a labelled diagram of an anther lobe at microspore mother cell stage. Q.50. The number of ovules in an ovary may be one (wheat, paddy and mango) to many (papaya, water melon and orchids).
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