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

SECTION - A

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

Q. 1. Which statement correct regarding Biston betularia, a species of moth found in England during the late 19th century?
(a) The black colouration of moth was caused by pollution from burning coal.
(b) Black moths were covered with soot from coal burning factories
(c) These moths were killed by devastating fungus Phytophthora
(d) An occasional mutation caused black moths to be born
Ans. (a)

 

Q. 2. Which of these is not a part of the inflammatory response?1
(a) Antibodies
(b) Swelling
(c) Redness
(d) Presence of histamine
Ans. (c)

 

Q. 3. Placing a ripe apple in a bag of green bananas will cause them to ripen quickly. This occurs because the apple.1
(a) absorbs cytokinin
(b) forms digestive enzymes
(c) lacks auxin
(d) produces ethylene
Ans. (d)

 

Q. 4. When alleles move into different gametes, this demonstrates 1
(a) Dominance
(b) Segregation
(c) Crossing over
(d) Independent assortment
Ans. (b)

 

Q. 5. Which ion is involved in blood clotting?1
(a) K+
(b) Na+
(c) Fe+++
(d) Ca++
Ans. (d)

Q. 8. Give the full form of SCID. 1

SECTION - B

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

Q. 11. Describe how the foetus with Rh-positive blood gets affected if the mother is Rh-negative. 2

 

Q. 12. Name the ear ossicles in the order of arrangement in humans. What roles do they play in hearing? 2

SECTION - C

Q. Nos. 19-27 are of short answer type carrying 3 marks each. Only one of these questions (Q. 27) based for drawing skill has internal choice. Answer, the rest in approximately 30-50 words each.

Q. 20. What is root pressure? How can you demonstrate it experimentally? 3

 

Q. 22. Name the disorder in which the immune mechanism of the body of a patient gets suppressed. Which pathogen is responsible for it? Give any two methods of its transmission? 3

SECTION - D

Q. Nos. 28-30 are long answer type carrying S marks each of these two questions. Q. Nos. 29 and 30 have internal choice. Answer the questions in approximately 80-120 words each.

Q. 28. Describe the C4 pathway in a sugarcane plant. How is this pathway an adaptive advantage to the ptant? 5

Q. 30. What is cardiac cycle? Describe the events that occur during joint diastole and atrial systole. 5
Or
List the different groups of hormones secreted by adrenal cortex. Give specific region of secretion and one major function of each. Name the disorder that may occur in a human if the adrenal cortex is destroyed.