KENDRIYA VIDYALAYA SANGATHAN: HYDERABAD REGION
PRE–BOARD 1: 2024–2025
SET 2 MARKING SCHEME
CLASS XII
SUBJECT: BIOLOGY
TIME: 3 Hrs. MAXIMUM MARKS: 70
General Instructions:
(i) All questions are compulsory.
(ii) The question paper has five sections and 33 questions. All questions are compulsory.
(iii) Section–A has 16 questions of 1 mark each; Section–B has 5 questions of 2 marks each;
Section– C has 7 questions of 3 marks each; Section– D has 2 case-based questions of 4
marks each; and Section–E has 3 questions of 5 marks each.
(iv) There is no overall choice. However, internal choices have been provided in some questions.
A student has to attempt only one of the alternatives in such questions.
(v) Wherever necessary, neat and properly labeled diagrams should be drawn.
SECTION–A
Q. No. Question Marks
1) The given diagram shows microsporangium of a mature anther. Identify A, B
and C.
(a) A-Middle layer B-Endothecium C-Tapetum
(b) A-Endothecium B-Tapetum C- Middle layer
(c) A-Endothecium B-Middle layer C-Tapetum
(d) A-Tapetum B-Middle layer C-Endothecium
Ans. (c)
2) A human male decides to adopt a surgical method for contraception. Identify 1
the point in the diagram where a cut would be made and tied.
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, (a) Point S (b) Point R (c) Point Q (d) Point P
Ans. (C)
3) Given below is a Karyotype of a human foetus obtained for screening to find
any probable genetic disorder:
Based on the Karyotype, the chromosomal disorder detected in unborn foetus
and the consequent symptoms the child may suffer from are:
(a) Turner’s syndrome: Sterile ovaries, short stature.
(b) Down’s syndrome: Gynaecomastia, overall masculine stature.
(c) Turner’s syndrome: Small round head, flat back of head.
(d) Down’s syndrome: Furrowed Tongue, short stature.
Ans. (A)
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, 4) Identify the category of genetic disorder depicted in the pedigree chart given 1
below:
(A) X-Linked recessive (B) X-Linked dominant
(C) Autosomal recessive (D) Autosomal dominant
Ans. (C)
5) Identify the region ‘X’, the factor ‘Y’ and the enzyme ‘Z’ involved in the 1
process of transcription in prokaryote as shown in the schematic representation
given below.
Region ‘X’ Factor ‘Y’ Enzyme ‘Z’
(a) Terminator Sigma (σ) RNA polymerase
(b) Promoter Rho (ρ) RNA polymerase
(c) Promoter Sigma (σ) RNA polymerase
(d) Promoter Sigma (σ) DNA polymerase
Ans. (c) / X = Promoter, Y = Sigma factor, Z = RNA polymerase.
6) Identify A, B and C in the given diagram. 1
a) A. DNA, B. H1 histone, C. Histone octamer
b) A. Histone octamer, B. DNA, C.H1 histone
c) A. DNA, B. Histone octamer, C. H1 histone
d) A. Histone octamer, B. H1 histone, C. DNA
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PRE–BOARD 1: 2024–2025
SET 2 MARKING SCHEME
CLASS XII
SUBJECT: BIOLOGY
TIME: 3 Hrs. MAXIMUM MARKS: 70
General Instructions:
(i) All questions are compulsory.
(ii) The question paper has five sections and 33 questions. All questions are compulsory.
(iii) Section–A has 16 questions of 1 mark each; Section–B has 5 questions of 2 marks each;
Section– C has 7 questions of 3 marks each; Section– D has 2 case-based questions of 4
marks each; and Section–E has 3 questions of 5 marks each.
(iv) There is no overall choice. However, internal choices have been provided in some questions.
A student has to attempt only one of the alternatives in such questions.
(v) Wherever necessary, neat and properly labeled diagrams should be drawn.
SECTION–A
Q. No. Question Marks
1) The given diagram shows microsporangium of a mature anther. Identify A, B
and C.
(a) A-Middle layer B-Endothecium C-Tapetum
(b) A-Endothecium B-Tapetum C- Middle layer
(c) A-Endothecium B-Middle layer C-Tapetum
(d) A-Tapetum B-Middle layer C-Endothecium
Ans. (c)
2) A human male decides to adopt a surgical method for contraception. Identify 1
the point in the diagram where a cut would be made and tied.
Page 1 of 18
, (a) Point S (b) Point R (c) Point Q (d) Point P
Ans. (C)
3) Given below is a Karyotype of a human foetus obtained for screening to find
any probable genetic disorder:
Based on the Karyotype, the chromosomal disorder detected in unborn foetus
and the consequent symptoms the child may suffer from are:
(a) Turner’s syndrome: Sterile ovaries, short stature.
(b) Down’s syndrome: Gynaecomastia, overall masculine stature.
(c) Turner’s syndrome: Small round head, flat back of head.
(d) Down’s syndrome: Furrowed Tongue, short stature.
Ans. (A)
Page 2 of 18
, 4) Identify the category of genetic disorder depicted in the pedigree chart given 1
below:
(A) X-Linked recessive (B) X-Linked dominant
(C) Autosomal recessive (D) Autosomal dominant
Ans. (C)
5) Identify the region ‘X’, the factor ‘Y’ and the enzyme ‘Z’ involved in the 1
process of transcription in prokaryote as shown in the schematic representation
given below.
Region ‘X’ Factor ‘Y’ Enzyme ‘Z’
(a) Terminator Sigma (σ) RNA polymerase
(b) Promoter Rho (ρ) RNA polymerase
(c) Promoter Sigma (σ) RNA polymerase
(d) Promoter Sigma (σ) DNA polymerase
Ans. (c) / X = Promoter, Y = Sigma factor, Z = RNA polymerase.
6) Identify A, B and C in the given diagram. 1
a) A. DNA, B. H1 histone, C. Histone octamer
b) A. Histone octamer, B. DNA, C.H1 histone
c) A. DNA, B. Histone octamer, C. H1 histone
d) A. Histone octamer, B. H1 histone, C. DNA
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