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

Time: 2 hours
Maximum Marks: 50

Note : Answer Part I and Part II in separate answer books.

PART I

SECTION A

A1. Define any five of the following terms : (5)

(a) Endothelium

(b) Tyloses

(c) Monopodial growth

(d) Somatic enbryogenesis

(e) Abscission

(f) Heteromorphic incompatibility

(g) Lenticels

SECTION B

B2. Draw labelled diagrams of any two of the following. (5)

(a) L.S. Wheat embryo

(b) T.S. Bignonia stem showing secondary growth

(c) Mature seed-coat in cotton

B3. Differentiate between secretory and amoeboid tapetum. Draw suitable diagrams for each. (5)

OR

Describe the mechanisms developed by plants to prevent sell-pollination and promote cross-pollination.

SECTION C

C4. (a) Explain the term dendrochronology. What are its applications ? (4)

(b) What are the different types of endosperm development ? (4)

C5. Describe an in vitro technique used to obtain virus-free plants from infected individuals. (5)

OR

Discuss the role of phytohormones in apical dominance.

PART II

Note : Answer all questions.

SECTION A

Fill in the blanks :

A1. Uteroplacental circulation occurs due to the development of blood-filled ____ layer of trophoblast. (1)

A2. The malignant growth that originates from the connective tissue and their derivatives is known as ____ . (1)

A3. The tail of mammalian spermatozoan has a core consisting of ____ microtubules. (1)

A4. Answer the following in 1-2 lines :

(a) What are the various cell layers produced from the cells of the 'inner cell mass' of the mammalian embryo ? (1)

(b) Name the three zones from the inner to outer side of neural retina. (1)

SECTION B

Answer the following questions in not more than 200 words.

B1. Describe the biochemical changes during metamorphosis of frog.

B2. What is secondary induction ? Also give one example each of permissive interaction and instructive interaction during secondary induction.

OR

Enumerate the extrinsic factors that control growth.

B3. Answer any two of the following: (5)

(a) Describe superficial cleavage in insects.

(b) Explain capacitation of sperms in mammals.

(c) Describe the secondary egg envelopes in chick.

(d) Describe the development upto blastocyst stage in mammals.

SECTION C

Answer the following questions in not more than 500 words

C1. Give an account of complete metamorphosis in insects mentioning the role of hormones during such metamorphosis. (5)

OR

Describe the process of gastrulation in amphibians

C2. Describe the process of differentiation of lens in vertebrates. (5)

OR

Discuss the similarities and differences between regeneration and embryonic development.