Growth and Reproduction — DU B.Sc. (Hons) Biological Sciences Previous Year Question Papers

Attempt four questions in all. 1. (a) Define the following terms: 5x1=5 (i) Primitive streak (iii) Connective (b) Fill in the blanks with suitable words: 10×1=10 (i) .. are basic nuclear proteins that replace histones during the final stages of sperm development. (ZZ) In humans, Hensen's node is essential for establi.shing the during early eninryogenesis. (}.Z£) .Harmful compounds formed by non-enzymatic reactions between sugars and proteins that accumulate during aging are caued...................... (Zu) The outer cell layer of the blastocyst that contributes to placenta formation is the ................. „ ............. (I;) Poriddal anther dehiscence can be seen in family ....................... (u£) ..................................... is an example of a nuclear endospelm I (uz.'£) Seed dispersal by water i-s.known as ................................. (uzj£) The entry of the .pouen tube in the ovule through the integuments is knorm a.s ............ (ir) is the natural proc6ss by which plants shed various parts, such as leaves, fiutts, flowers, or seeds. (a;) .hi.„ ................... `.......... enforyo sac, au the four megaspore nuclei take pat in the developmcht of the female ,gametopkyte. 2. (a[) Distinguish between the following (any ffaree) : (i) Bilaminar and trilaminar disc Spermatogenesis and .Oogenesis Free Radical 'theory and Mutation accupr:ulation theory Radial Cleavage and Discoidal Cleavage. Write short notes on any fowo of the following : , 2x4.5=9 P-raw weH I-a-ben-ed-diagrams of t~he foHowhg (any a-zuo)` : 2-x2.5=5 (i) L. S. Anatrobous ovule (G.Z) Pdygoinm type of Embryo sac (I.I.Z) T.S. young anther showing Inicrospore Ihother cell. Describe the ABC model of floral organ identity wi.th the help of suitable diagram. Discuss the various stages involved in.Anther dehiscence with the help of well labelled diagrams. 5 Explain how placentas are classified, describe the essential functions of the placen'ta duing pregnaney and enumerate the hormones synthesized by the placenta. 8 Describe the different modes of implantation across species and discuss in detail the process of blast.ocyst implantation in humans. 7 With the help of well. labelled diagrams, compare and contrast the apical and lateral meristems, detailing their location, function, and the types of .growth they enable. (b) Trace the sequence of developmental stages in dicot embryogenesis, from the zygote to the mature embryo. Support your answer with labelled 6. Differentiate any five: (a) Amoeboid and Secretory tapetum (c) Self and Cross Pollination (d) Capacitation and Acrosome reaction (e) Discoblastic cleavage and Superficial cleavage (f) Estrus and Menstrual cycle.