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

Time: 2 hours
Maximum Marks: 50

PART I

SECTION A

Question A1 to A5 are compulsory. Choose the correct answer from the alternatives given. (1 x 5 = 5)

A1. The age of tree can be determined by

(a) stem diameter

(b) size of apical meristem

(c) study of sieve plates

(d) number of growth rings

A2. Primary endosperm is the fusion product of

(a) two polar nuclei and a male gamete

(b) antipodal cells and a male gamete

(c) one polar nucleus and an antipodal cell

(d) the two polar nuclei

A3. A fruit which is produced by parthenocarpy is

(a) Wheat

(b) Litchi

(c) Banana

(d) Coconut

A4. Apical dominance is caused by

(a) Cytokinins

(b) Ethylene

(c) Auxins

(d) Gibberellic acid

A5. Stem of Bignonia shows

(a) successive cambia

(b) Interxylary phloem

(c) furrowed xylem

(d) fluted vascular cylinders

SECTION B

Attempt any two questions.

B1. Distinguish between any two of the following pairs:

(a) Vascular cambium and Cork cambium

(b) Somatic embryogenesis and Zygotic embryogenesis

(c) Sap wood and Heart wood

(d) Tenuinucellate and Crassinucellate ovules

B2. Draw labelled diagrams of any two of the following:

(a) Median Longitudinal section of malure embryo of Triticum

(b) Aleurone cell

(c) An organized embryo sac

(d) T.S. of another showing various wall layers

B3. What is apomixis ? How would you differentiate between recurrent and non-recurrent types of apomixis ? (2 + 3 = 5 )

SECTION C

Attempt any two questions.

C1. What structural features determine the various uses of wood ? Give one example each of wood used for construction, furniture, matches, curving and life rafts.(2 + 2 + 1 = 5)

C2. What is cellular totipotency ? Give a summary diagram of production of androgenic haploids and homozygous diploid plants from them (1 + 3 = 5)

C3. Describe the factors involved in seed dormancy. (5)

PART II

Answer the questions as directed under each section.

SECTION A

Answer all the questions. Fill in the blanks in questions A1, A2 and A3.

A1. In vertebrates, the primordial germ cells are derived from ____ and the cells which form the gonads are derived from ____

A2. The first late map of a urodela embryo was constructed in 1929 by ____ . He used agar chips soaked in ____ to label the embryonic cells.

A3. The growing oocytes in mammalian ovary are surrounded by two kinds of accessory cells called ____ and ____ .(1)

A4. Differentiate between any two of the following : (1 + 1)

(i) Sarcoma and Carcinoma

(ii) Allometric and isometric growth

(iii) Karyokinesis and Cytokinesis

SECTION B

Answer all questions in not more than 200 words for each.

B1. Explain any two of the following:

(i) Genomic equivalence of nuclei

(ii) Role of Prolactin and Thyroxine in the growth and metamorphosis of amphibian larvae

(iii) Cleavages and formation of blastocyst in mammals

B2. (i) What is meant by differentiation in animal development ? Mention the steps involved in the process of differentiation.

(ii) List the major tissues and organ systems derived from ectoderm and mesoderm in vertebrates.

OR

(i) What is meant by Limb morphogenesis ?

(ii) Describe briefly the outcome of experiments performed on combinations of avian wing and leg ectoderm and mesoderm. (1 + 4 = 5)

SECTION C

Answer any two questions. Answers should not exceed 500 words for each question.

C1. (i) Define aging.

(ii) List any four changes during aging in human body.

(iii) Explain the somatic mutation theory of aging (1 + 2 + 2 = 5)

C2. Describe the sequence of events In limb regeneration after amputation in urodela amphibians. (5)

C3. Describe the permissive interaction between mesoderm and endoderm as it occurs in the development of pancreas in mammals. (5)