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

Time: 2 hours
Maximum Marks: 50

PART I

SECTION A

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

(a) Somalic hybrid

(b) Heartwood

(c) Apomixis

(d) Quiescent center

(e) Syngamy

(f) Thigmolropism

(g) Aril

SECTION B

2. With the help of diagrams only describe the development of (a) Pollen wall or (b) Fritillaria type of embryo sac.(5)

3. Discuss the role of endosperm in the nutrition of embryo.(5)

OR

Differentiate between gametophyte and sporophyte types of self-incompatibility.

SECTION C

4. Briefly discuss the role of plant tissue culture in crop improvement.(5)

OR

Describe the various types of cambial variants in anglosperms.

5. Discuss the biochemical changes during chloroplast senescence.(5)

OR

Discuss the role of phytohormones in flowering and sex expression.

PART II

Answer all Questions

SECTION A

Fill in the blanks.

A1. The regular replacement of erythrocytes in vertebrates is an example of ____ regeneration.(1)

A2. During fertilization of mammals, the spermatozoa penetrates the zona pellucida of ovum using of enzyme ____ .(1)

A3. The process of loss of specific parts of chromosomes in the blastomeres deslined to become somatic cells in Ascaris is known as ____ .(1)

A4. Differentiate between any two the following (answers should not exceed 2-3 lines):

(a) Oncogenes and proto-oncogenes(1)

(b) Blastula and blastocyst(1)

(c) Effects of colchicine and cytochalasin B treatment of egg undergoing cleavage.(1)

SECTION B

Answer the following questions is not more than 200 words.

B1. Write short notes on any two of the following:(21/2+21/2)

(a) Neoteny

(b) Changes generally associated with senescence in human being

(c) Secondary egg envelopes in chick

B2. Elaborate the process of lens regeneration in amphibians.(5)

OR Describe different methods of determining the fate maps of blastula.

SECTION C

Answer should not exceed 500 words.

C1. Describe various stages of primitive streak formation in chick.(5)

OR

Define and differentiate between the terms hyperplasia, anaplasia and metastasis. Also describe the three stages of carcinogenesis.

C2. Describe the process of differentiation of retina in amphibians.(5)

OR

Describe the extraembryonic membranes and placenta in human being.