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

Time: 2 hours
Maximum Marks: 50

Note : (i) Answer Part I and Part II in seperate answer copies.

(ii) Draw labelled diagram wherever necessary.

PART I

SECTION A

Question 1 is compulsory.

1. Fill in the blanks.

(a) ____ is the innermost layer of the anther wall.

(b) The embryo development from unfertilized egg is called ____ .

(c) The main types endosperm development in angiosperms are : (i) Nuclear (ii) ____ and (iii) Helobial.

(d) The axial parenchyma and the ____ parenchyma are present in secondary xylem.

(e) The cambium that differentiates within the bundles of primary vascular tissue is called ____ cambium.

SECTION B

Note : (i) Attempt any four questions.

(ii) All questions carry equal marks.

2. With the help of diagrams only distinguish between Anatropous ovule and Campylotropous ovule.

3. Explain the structure and functions of synergids.

4. Give one example each of

Composite endosperm

Ruminate endosperm

Mosaic endosperm

Interxylary phloem

Polyembryony

5. Write a short note on origin, site of occurrence and significance of tyloses.

6. Differentiate between fusiform initials and ray initials.

SECTION C

Note : (i) Attempt any two questions.

(ii) All questions carry equal marks.

7. Explain the physiological effects of auxins and gibberellins on growth and development of plants. (5)

8. Describe the structure and role of aril, caruncle and operculum. (5)

9. What do you understand by the term 'geotropism' ? Explain the mechanism of perception and response. (5)

10. (a) Briefly describe clonal propagation. (2 + 3 = 5)

(b) Explain the procedure for Bergmann's method of cell plating.

PART II

Note: Answer all questions.

SECTION A

Fill in the blanks.

A1. In insects, the ____ released from corpora allata is responsible for retention of larval characters while ecdysone promotes ____ process. (1)

A2. In human development, the implantation of blastocyst outside the uterus is refered to as ____ implantation. (1)

A3. In urodele amphibians, the chromosomes of the developing oocyte during vitellogenesis phase become

characteristic and are called ____ chromosomes. (1)

A4. Define in 1 or 2 lines any two of the following :

(a) Proto-oncogenes (1)

(b) Involution (1)

(c) Neoteny (1)

SECTION B

Answer the following questions in not more than 200 wards.

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

(a) physiological and biochemical changes in aging.

(b) Describe the processes of holoblastic and meroblastic cleavage.

(c) Origin of regeneration cells of blastema after amputation of limb in salamander.

(d) Metastasis.

B2. Enumerate the various tissues and structures derived from ectoderm, mesoderm and endoderm during human development.

OR

Explain the interaction of hormones during metamorphosis in insects. (5)

SECTION C

Answer the following questions in not more than 500 words.

C1. Explain any two of the following. (5)

(a) Methods of constructing fate maps of early blastula.

(b) Modes of cell movement during morphogenesis and organogenesis.

(c) Neurulation in amphibia.

(d) Extrinsic factors controlling growth.

C2. Describe the process of Primitive streak formation in chick. (5)

OR

Describe the instructive interactiion between ectoderm and mesenchymal cells in the development of feathers in chick. (5)