Paper C-11 Reproductive Biology of Angiosperm 2023 Question Paper with Answer Under Dibrugarh University

 প্ৰিয় অণুজসকল আজিৰ এই লেখাটি ,লেখাবুলিয়েই কৈছো কাৰণ এইটো লিখিয়ে প্ৰকাশ কৰিছো।এই লেখাটি আজি ১৭/১১/২০২৩ চনৰ তাৰিখে মহাবিদ্যালয়সমুহত পঞ্চম ষণ্মাসিকসমুহৰ পৰীক্ষা চলি আছে আৰু এই পষ্টটোত তাৰেই কিছু আভাস । এই পষ্টটোত আছে প্ৰশ্ন Bsc Fifth semester CBCS Under Dibrugarh University । বিষয় হৈছে উদ্ভিদ বিজ্ঞান বিভাগৰ  Paper C-11 Reproductive Biology of Angiosperm".প্ৰশ্ন কাকত প্ৰশ্নসমুহ তলত দিয়া হ'ল আৰু এইখিনিতে জনাই থওঁ এই প্ৰশ্নটো আগবঢ়াইছে লক্ষীমপুৰ তেলাহী কমলাবৰীয়া মহাবিদ্যালয়ৰ ছাত্ৰী সুনিতা পেগুৱে।

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Reproductive  Biology Of Angiosperm

                                                Full Mark :53

                                                    Pass Mark :21

                                                Time :- 3 Hours

 

1.Answer the following as directed :

(a)______ discovered double fertilization in angiosperms.

(b)Ovule changes into fruit/Seed/Flower .

(c)The most primitive tuypes of ovule is ______.

(d) The study of Pollen is known as Palaeontology /Palynology/Embryology.

(e)Allium type of embryo sac  is monosporic /bisporic/tetrasporic.

2.Write the precies notes on the following (any three):  4*3=12

(a)Function and types of tapetum.

(b)Different kinds of endosperm.

(c)Apomixis and its significance

Answer :- Apomixis and its significance

Apomixis :-Apomixis is flowering plants is defind as the asexual formation of a seed froim the maternal tissue  of the ovule,avoiding the process of meiosis and fertilization ,leading to embryo development.

                         The Phenomenon   of appomixis ovule all the non sexuall method of reproduction in which the reproducing sportes are developed without fusion.

Click now :-Reproductive Biology angiosperm bsc fifth semester 2022 dibrugarh university

(d)Ontogeny of flower

(e)Parasexual hybridization.

3.Describe the different contivances or mechanisms to perform cross-pollination.Why does nature prefer cross-pollination.                                                                                                                        10+2=12

                                                                Or

What is NPC System of classification ?Write about the classification of pollen types based on NPC system.                                                                                                                                                      2+10=12

Answer :-NPC System  of classification :- NPC Classification  system is  classification of  pollen and spore based on the  three  feature  of the  aperature only i.e number ,position  and  character.Erdlman and Straka (1961)Proposed NPC System.

N----from number of Pollen.

P----from  position of pollen.

C---from  character of  pollen.

About the classification of pollen types based on NPC system.    :-

(i)Classification of Aperature  Based on Number  :-  In NPC system N denotes the number of Pollen  number of apperature present in pollen grains.SAperature pollen i.e pollen  having  aperature divided into  served  groups .The Groups are mentiond as N1,to N10 .Each group has characteristic  number mof aperature  i.ew N has one aperature  and N2 has  two  aperature and so on.The N1 group has seven  or more aperature.

(ii)Classification  of aperature  based  on Position –In NPC system P denotes  the positioned of the pollen  of aperature in aq pollen grainds and spore.There are xsdven groups  of aperature based on position namely P0 to P6.Here P1 denotes to the number of one position lof pollen.

(iii)Clasification of Aperature based on Charracter :-In NPC system C denotes to the character of  of an aperature  in pollen grain and spore.

 

 

 

4.With suitable diagrams ,describe the different types of embryo sacs of angiosperms.              12

Answer :-Different types of  Embryosac of angiosperm:-  The  megaspore (n) makes the beginning  of the  megagametophyte (female gametophyte)generation .The nucleus of the megaspore  divides and develops into the female gametophyte or the embryo  sac.The female gametophyte of angiosperm is very much reduced  and totally dependent for its nutrition upon the tissue of the  sporophyte.

          The four megaspore takes part in the three types;-

(i)Monosporic/Normal/Polygonal type.

(ii)Bisporic embryo sac.

(i)Monosporic /Normal/Polygonal types:-The monosporic female gametophyte  may be 8-nucleate type or 4 nucleate type.The 8 nucleate type of female gametophyte  is the most common and ias there fore designated  as the  normal type.It is called polygonum type as this  type was first illustrated  by  starburger  in polygonum div ariatum.

Oenothera  type :- Anther variation of monosporic type of embryo of embryo sac is known as  the oenothera type  and has been reproducted  only in the family onagraceae.In this  type  the  megaspores nucleus divides  twice and thus  produce  four nuclei give  rise to a normal  egg apparatus and single  polar nuclei.

(ii)Bisporic embryo sac :- The bisporic embryo sac are typically 8-nucleate.The bisporic embryo sac develops from  one of the two dyads formed  as a result of the  first meiotic  division .One of the dyads degenerates both the nuclei  of the  functional dyads part in the formation of embryo sac. Each nucleus  undergoes two meiotic  divisions  and such  the mmature embryo-sac is  8 nuclei.On the basis of the position pof  functional  dyad the following types have been recognized  in bisporic  embryo-sacs.

(a)Allium type :- The megaspore mother cells divides to from  two cells the upper  one quickly degenerates .The lower one than divides and forms two nuclei distributed in the two poles.

(b)Endomion types :- this type develops from the micropylar dyad.

(c)Tetrasporic type :-In the tetrasporic  female gametophyte cell four megasporic  female gametophyte  all four nuclei  take part in the formation of the  gametophyte .Here all four megaspore  nuclei  lie free within  the single cell after meiosis  of  megaspore  mother cell.

(i)Adoxa type :-Found  in adoxa .In thius type  the four megaspore nuclei undergo one  more division  forming  8- nuclei  undergo one more nuclei  part in the  formation 8 nuclei.All the eight gametophyte  i.e gametophyte having a normal  egg apparatus 2 pollar  nuclei and 3 antipodal cells.

(b)Plumbago type :- In this type also only  one post-meiotic  occurse  but the organization  of the mature  embryo sac is very different from  that  adoxa type the mature embryo sac  comprisewd  egg cell and a four  nucleate centrall cell.

                                                Or

Write notes on the following:              4*3=12

(a)Male germ unit (MGU)

(b)Self-incompability

(c)Microsporogenesis

Ans:-Microsporogenesis :- The Primary sporogenous layers form the sporogenus tissue  give rise to the  microspore mother cells or pollen mother cells.The Microspore mother or pollen mother which are at briefly  polygonads closely packed gradually become rounded   and loosely arranged in the rapidly enlarging microarranged in the rapidly enlarge microsporangium.Although all the mother cells in an anther are capable of giving rise to pollen grains but some of them  may degenerate and serve as food material for the remaining cells which give rise to pollen grains.Each Functional spore mother cells produces four  microspore or pollen grains.

5.With suitable diagram ,write briefly about the development                 of embryo in dicots.              12

Answer :- Development of Dicot Embryo :- The zygote divides transversly from a two celled pro embryo.The cell towards  the microspro pyle is known as the basal cell and  other is known  gterminal cell.The basal cell undergoies several  transeverse  division to ferom a long suspensor .The terminal cell divides twice  to  four  cells .This four celled stage of terminal  cell c alled quardrant stage .The four cell I of the quardrant stage now divides transversely  to form an octant stage of eight cells arranged in two tiers of four cells.The lower  tier gives rise to the tip and cotyledons while the upper tier is means for the formation of hypocotyledons.

                    This  is followed  by periclinical  divisions is the octant cells. The eight  outer cells from  the dermatogens ,which  divide anticlinically  and develop into the epidermis.The inner cells from  the periblem and stele from the plerome .The basal  cell divides several times to from  a long suspensor of six to ten cells. The  lowermost cell of the suspensor nearest to the  developing  embryo  is known as hypophytes .The hypostesis  by repeated  divisions  gives rise to root cap ,epidermis  and cortex of rooyts.

                                     Further enlargement of hypocotyledons and cotyledon result  in a curvature of the coityledons result in a curvature of the cotyledons.The  embryo at thois  stage appear as  a horse-shoe  shaped  structure .In the mature embryo ,the stum  tips terminal and  the  two cotyledons occupy the  lateral position.

                             Or

Write briefly about the various mechanisms of seed dispersal and its impotance.