Bachelor of Science (B.Sc.) - Life Science
Term-End Examination

Time: 2 hours
Maximum Marks: 50

Note: Answer Part I arid Part II in separate answer copies.

Answer the questions as per instructions in each section.

PART I

PLANT

SECTION A

Note : (i) Question 1 is compulsory.

(ii) Draw labelled diagrams wherever necessary.

1. Fill in the blanks: (5)

(i) The male germ unit (MGU) is constituted of ____ and ____ .

(ii) Three important constituents of the medium for in vitro pollen germination are ____ and ____ .

(iii) Jute fibers are obtained from ____ tissue of Corchorus plant.

(iv) Breakdown of starch in cereal grain is stimulated by ____ produced by its embryo during germination.

(v) In angiosperms, meiocytes are generally surrounded by a ____ wall which acts as a selective barrier.

(vi) In Mangifera and Citrus, plural embryos arise from ____ .

(vii) ____ of a plant is generally free of virus and is cultured to obtain virus-free plantlets.

(viii) Tissue of non-suberized living cells cut off towards the inner side by the cork cambium is called ____ .

(ix) Chemically exine is composed of ____ .

(x) A form of reproduction without meiosis and syngamy is called ____ .

SECTION B

Note : (i) Attempt any two questions.

(ii) All questions carry equal marks.

2. Differentiate between (in any two) (5)

(i) Amoeboid and secretary tapetum

(ii) Endotheliurn and endotheciurn

(iii) Operculum and caruncle

(iv) Monosporic and bisporic types of embryo sac

(v) Nuclear and helobial types of endosperm development

3. Write the significance/importance of any two of the following (5)

(i) Sexual incompatibility

(ii) Parthenocarpy

(iii) Polyembryony

(iv) Pollen-wall proteins

4. Discuss the functions of any two of the following in relation to their structure (5)

(i) Tapetum

(ii) Synergids

(iii) Suspensor

5. Write short notes on any two of the following :

(i) Entomophily

(ii) Nutrition of embryo sac

(iii) Test tube pollination

(iv) Composite endosperm

SECTION C

Note: Attempt any two questions.

6. What is the significance of seed dormancy ? List the factors causing seed dormancy. Describe any two methods of overcoming seed dormancy. (5)

7. Differentiate between somatic hybridization and cybridization. How can the two techniques be used in the improvement of crops ? (5)

8. What are the factors responsible for floral induction ? Describe the salient changes in the shoot meristern during floral induction. (5)

PART II

ANIMAL

SECTION A

Note : Answer all questions.

Fill in the blanks in questions A1 to A3.

A1. In insects, the ____ released from corpora allata is responsible for the retention of larvall/hymphal characters.

A2. To facilitate penetration of sperm into the egg, the acrosome of the sperm releases an enzyme called ____ .

A3.. The regular replacement of epidermal cells in the skin of vertebrates is an example of ____ regeneration.

A4. Differentiate between any two pairs of the following (1 x 2 = 2)

(a) Ecdyone and Ecdysterone

(b) Oncogenes and Proto-oncogenes

(c) invagination and Involution

SECTION B

Note: Answer all the questions. Each answer should not exceed more than 200 words.

B1. Write short notes on any two of the following: (5)

(a) Neurulation in amphibians

(b) Metastasis

(c) Neoteny

B2. Describe different methods of determining the fate maps of blastula. (5)

OR

Give the diagrammatic representation of all the stages of oogenesis. (5)

SECTION C

Note: Answer all questions, Each answer should not exceed more than 500 words.

C1. Describe the process of primitive streak formation in chick. (5)

OR

Describe the extra embryonic membranes and placenta in human beings

C2. Write short notes on any two of the following: (5)

(i) Primary embryonic induction

(ii) Limb regeneration in amphibia

(iii) Extrinsic factors controlling growth