Paper : CBSE Class 12th Biology Exam Paper, 2003 (Compartment Delhi: Set-2)

SECIION - A

Q. Nos. 1-8 are of very short answer type carrying I mark each. Of these the first five questions are of multiple choke type which have to be answered simply as A, B, C or D. The remaining questions have lobe answered in approximately 1—20 words each.

Q. 2. A girl has the blood group A. What is true of the inberitance of this blood group in her case?
(a) Her mother should be homo O
(b) Both her parents should be with O group blood
(c) Her father could be heterozygous B
(d) Both her parents could be hetérozygous A
Ans. (d)

Q. 3. An example of a dioecious plant is
(a) Cucumber
(b) Maize
(c) Castor beans
(d) Date-palm
Ans. (d)

Q. 4. Oozing of semisolid material in the throat which develops into a tough membrane causing choking of the air passage often leading to the death of the baby, are symptoms of
(a) Tuberculosis
(b) Cholera
(c) Diphtheria
(d) Chicken pox
Ans. (c)

Q. 5. Pick out the false statement pertaining to acromegaly.
(a) Over-secretion of somatotropin after adolescence causes this disease
(b) The person gets a giant stature
(c) Long bones of the limbs elongate
(d) The person looks like a gorilla

Q. 7. Glomerular filtrate has water, glucose, amino acids and creatinine. Which of them are rapidly reabsorbed actively by blood?

SECTION - B

Q. Nos. 9-18 are of short answer type carrying 2 marks each. Answer them in 20-30 words each.

Q. 9. Mention the unusual function performed by
(i) tap root of turnip
(ii) leaves of cactus

Q. 16. Explain any four cellular changes that occur in human beings with ageing.

Q. 18. How and why is electroporation done in E. coil?

SECTION - D

Q. Nos. 28-30 are long answer type c 5 marks each. Q. Nos. 29 and 30 have internal choke. . Answer these questions in approximately 80-120 words each.

Q. 29. (a) Draw an electron-microscopic view of a mammalian sperm. Label any six internal structures of the sperm.
(b) What do you call the area of an ovum from where the sperm makes its entry?
(c) Name the enzyme produced by the sperm to facilitate its entry.

Or

(a) Draw a labelled diagram of a myelinated neuron showing one motor end plate.
(b) Name the mode of nerve impulse conduction along a myelinated nerve fibre.
(c) Besides blood, what supplies nutrients to the neurons in the brain?

Q. 30. Illustrated below is a DNA segment which constitutes a gene:

(a) Will the whole gene be transcribed into RNA primarily? State “yes” or “no”.
(b) Name the shaded and the unshaded parts of the gene.
(c) Explain how these genes express.
(d) How is this gene different from prokaryotic gene in its expression?

Or

A geneticist was tracing the inheritance of eye colour in Drosophila flies. He crossed a red eyed female with a white eyed male.
(a) What should be the phenotypes of the flies the geneticist should select if he wanted to perform a reciprocal cross Represent the reciprocal cross showing the phenotypes and genotypes of the selected flies and their progeny
(b) What is established through the results of a reciprocal cross with reference to the inheritanc of a trait in general’