Page 1
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ISC SPECIMEN QUESTION PAPER 2025
1
BIOLOGY
PAPER 1
(THEORY)
Maximum Marks: 70
Time Allotted: Three Hours
Reading Time: Additional Fifteen Minutes
Instructions to Candidates
? You are allowed additional fifteen minutes for only reading the question
paper.
? You must NOT start writing during reading time.
? This question paper has 11 printed pages. It has 18 questions in all.
? Answer all questions.
? There are four sections in the paper: A, B, C and D. Internal choices have
been provided in one question each in Sections B, C and D.
? Section A consists of one question each carrying one / two mark(s).
? Section B consists of seven questions each carrying two marks.
? Section C consists of seven questions each carrying three marks.
? Section D consists of three questions each carrying five marks.
? Diagrams should be drawn wherever necessary using a pencil only.
? The intended marks for questions are given in brackets [ ].
Instruction to Supervising Examiner
? Kindly read aloud the Instructions given above to all the candidates present
in the examination hall.
Page 2
----------------------------------------------------------------------------------------------------------------------
ISC SPECIMEN QUESTION PAPER 2025
1
BIOLOGY
PAPER 1
(THEORY)
Maximum Marks: 70
Time Allotted: Three Hours
Reading Time: Additional Fifteen Minutes
Instructions to Candidates
? You are allowed additional fifteen minutes for only reading the question
paper.
? You must NOT start writing during reading time.
? This question paper has 11 printed pages. It has 18 questions in all.
? Answer all questions.
? There are four sections in the paper: A, B, C and D. Internal choices have
been provided in one question each in Sections B, C and D.
? Section A consists of one question each carrying one / two mark(s).
? Section B consists of seven questions each carrying two marks.
? Section C consists of seven questions each carrying three marks.
? Section D consists of three questions each carrying five marks.
? Diagrams should be drawn wherever necessary using a pencil only.
? The intended marks for questions are given in brackets [ ].
Instruction to Supervising Examiner
? Kindly read aloud the Instructions given above to all the candidates present
in the examination hall.
---------------------------------------------------------------------------------------------------------------------
ISC SPECIMEN QUESTION PAPER 2025
2
SECTION A – 20 MARKS
Question 1
Answer the following questions briefly.
(i) Sapna has been diagnosed with an infection of the reproductive tract caused by
bacteria. She experiences burning sensation during urination, pain around her
genitalia and observes pus containing discharge. Her doctor tells her that this
infection has an incubation period of two to five days but can be cured.
What is the biological name of the causative agent of the disease Sapna is suffering
from? (Recall)
[1]
(ii) The number of chromosomes in the leaf cells of a male plant is 40 and in the
stem cells of a female plant is 60. If they are artificially hybridised, what will be
the number of chromosomes in the endosperm? (Application)
[1]
(iii) How many cycles of PCR are required to produce 250 molecules of DNA,
starting with a single parental strand? (Application)
[1]
(iv) Which is the most commonly prescribed non-steroidal oral contraceptive pill in
India? (Recall)
[1]
(v) Tall pea plants having green pods were crossed with dwarf pea plants having
yellow pods. Out of 80 plants, how many are likely to be tall plants in the F2
generation? (Application)
[1]
(vi) Write a 6-nucleotide long palindromic sequence on a double stranded DNA,
which was reverse transcribed by the following nucleotide sequence on a
retroviral RNA. (Create)
3’-GUA- - - 5’
[1]
(vii) In the given figure of mammalian spermatozoon, “X” is an organelle. Identify
the organelle. (Recall)
[1]
Page 3
----------------------------------------------------------------------------------------------------------------------
ISC SPECIMEN QUESTION PAPER 2025
1
BIOLOGY
PAPER 1
(THEORY)
Maximum Marks: 70
Time Allotted: Three Hours
Reading Time: Additional Fifteen Minutes
Instructions to Candidates
? You are allowed additional fifteen minutes for only reading the question
paper.
? You must NOT start writing during reading time.
? This question paper has 11 printed pages. It has 18 questions in all.
? Answer all questions.
? There are four sections in the paper: A, B, C and D. Internal choices have
been provided in one question each in Sections B, C and D.
? Section A consists of one question each carrying one / two mark(s).
? Section B consists of seven questions each carrying two marks.
? Section C consists of seven questions each carrying three marks.
? Section D consists of three questions each carrying five marks.
? Diagrams should be drawn wherever necessary using a pencil only.
? The intended marks for questions are given in brackets [ ].
Instruction to Supervising Examiner
? Kindly read aloud the Instructions given above to all the candidates present
in the examination hall.
---------------------------------------------------------------------------------------------------------------------
ISC SPECIMEN QUESTION PAPER 2025
2
SECTION A – 20 MARKS
Question 1
Answer the following questions briefly.
(i) Sapna has been diagnosed with an infection of the reproductive tract caused by
bacteria. She experiences burning sensation during urination, pain around her
genitalia and observes pus containing discharge. Her doctor tells her that this
infection has an incubation period of two to five days but can be cured.
What is the biological name of the causative agent of the disease Sapna is suffering
from? (Recall)
[1]
(ii) The number of chromosomes in the leaf cells of a male plant is 40 and in the
stem cells of a female plant is 60. If they are artificially hybridised, what will be
the number of chromosomes in the endosperm? (Application)
[1]
(iii) How many cycles of PCR are required to produce 250 molecules of DNA,
starting with a single parental strand? (Application)
[1]
(iv) Which is the most commonly prescribed non-steroidal oral contraceptive pill in
India? (Recall)
[1]
(v) Tall pea plants having green pods were crossed with dwarf pea plants having
yellow pods. Out of 80 plants, how many are likely to be tall plants in the F2
generation? (Application)
[1]
(vi) Write a 6-nucleotide long palindromic sequence on a double stranded DNA,
which was reverse transcribed by the following nucleotide sequence on a
retroviral RNA. (Create)
3’-GUA- - - 5’
[1]
(vii) In the given figure of mammalian spermatozoon, “X” is an organelle. Identify
the organelle. (Recall)
[1]
---------------------------------------------------------------------------------------------------------------------
ISC SPECIMEN QUESTION PAPER 2025
3
(viii) Observe the relation between the first two words and then fill in the fourth word.
Histamine: Mast cells :: Antibody: ____________ (Analysis)
[1]
(ix) Which of the following sequences of mRNA will NOT translate completely?
(Recall)
[1]
(a) 5' - AUG UUC AGC UCG UGA - 3'
(b) 5'- AUG AAC UAA CCA CUC - 3'
(c) 5' - AUG UUA CUC GCG UAA - 3'
(d) 5' - AUG CCA UAC GAC UAG - 3'
(x) Which one of the following choices reflects the correct number of chromosomes
in the zygote and in the second polar body of Drosophila melanogaster?
[1]
Zygote Meiocytes
I 08 08
II 04 08
III 08 04
IV 04 04
(a) I
(b) II
(c) III
(d) IV
(xi)
Given below are two statements marked Assertion and Reason. Read both the
statements carefully and choose the correct option. (Analysis)
Assertion: Earthworm is called a detritivore.
Reason: It breaks down the water-soluble inorganic nutrients, which percolate
down into the soil.
[1]
(a) Both Assertion and Reason are true and Reason is the correct explanation
for Assertion.
(b) Both Assertion and Reason are true but Reason is not the correct
explanation for Assertion.
(c) Assertion is true and Reason is false.
(d) Both Assertion and Reason are false.
Page 4
----------------------------------------------------------------------------------------------------------------------
ISC SPECIMEN QUESTION PAPER 2025
1
BIOLOGY
PAPER 1
(THEORY)
Maximum Marks: 70
Time Allotted: Three Hours
Reading Time: Additional Fifteen Minutes
Instructions to Candidates
? You are allowed additional fifteen minutes for only reading the question
paper.
? You must NOT start writing during reading time.
? This question paper has 11 printed pages. It has 18 questions in all.
? Answer all questions.
? There are four sections in the paper: A, B, C and D. Internal choices have
been provided in one question each in Sections B, C and D.
? Section A consists of one question each carrying one / two mark(s).
? Section B consists of seven questions each carrying two marks.
? Section C consists of seven questions each carrying three marks.
? Section D consists of three questions each carrying five marks.
? Diagrams should be drawn wherever necessary using a pencil only.
? The intended marks for questions are given in brackets [ ].
Instruction to Supervising Examiner
? Kindly read aloud the Instructions given above to all the candidates present
in the examination hall.
---------------------------------------------------------------------------------------------------------------------
ISC SPECIMEN QUESTION PAPER 2025
2
SECTION A – 20 MARKS
Question 1
Answer the following questions briefly.
(i) Sapna has been diagnosed with an infection of the reproductive tract caused by
bacteria. She experiences burning sensation during urination, pain around her
genitalia and observes pus containing discharge. Her doctor tells her that this
infection has an incubation period of two to five days but can be cured.
What is the biological name of the causative agent of the disease Sapna is suffering
from? (Recall)
[1]
(ii) The number of chromosomes in the leaf cells of a male plant is 40 and in the
stem cells of a female plant is 60. If they are artificially hybridised, what will be
the number of chromosomes in the endosperm? (Application)
[1]
(iii) How many cycles of PCR are required to produce 250 molecules of DNA,
starting with a single parental strand? (Application)
[1]
(iv) Which is the most commonly prescribed non-steroidal oral contraceptive pill in
India? (Recall)
[1]
(v) Tall pea plants having green pods were crossed with dwarf pea plants having
yellow pods. Out of 80 plants, how many are likely to be tall plants in the F2
generation? (Application)
[1]
(vi) Write a 6-nucleotide long palindromic sequence on a double stranded DNA,
which was reverse transcribed by the following nucleotide sequence on a
retroviral RNA. (Create)
3’-GUA- - - 5’
[1]
(vii) In the given figure of mammalian spermatozoon, “X” is an organelle. Identify
the organelle. (Recall)
[1]
---------------------------------------------------------------------------------------------------------------------
ISC SPECIMEN QUESTION PAPER 2025
3
(viii) Observe the relation between the first two words and then fill in the fourth word.
Histamine: Mast cells :: Antibody: ____________ (Analysis)
[1]
(ix) Which of the following sequences of mRNA will NOT translate completely?
(Recall)
[1]
(a) 5' - AUG UUC AGC UCG UGA - 3'
(b) 5'- AUG AAC UAA CCA CUC - 3'
(c) 5' - AUG UUA CUC GCG UAA - 3'
(d) 5' - AUG CCA UAC GAC UAG - 3'
(x) Which one of the following choices reflects the correct number of chromosomes
in the zygote and in the second polar body of Drosophila melanogaster?
[1]
Zygote Meiocytes
I 08 08
II 04 08
III 08 04
IV 04 04
(a) I
(b) II
(c) III
(d) IV
(xi)
Given below are two statements marked Assertion and Reason. Read both the
statements carefully and choose the correct option. (Analysis)
Assertion: Earthworm is called a detritivore.
Reason: It breaks down the water-soluble inorganic nutrients, which percolate
down into the soil.
[1]
(a) Both Assertion and Reason are true and Reason is the correct explanation
for Assertion.
(b) Both Assertion and Reason are true but Reason is not the correct
explanation for Assertion.
(c) Assertion is true and Reason is false.
(d) Both Assertion and Reason are false.
---------------------------------------------------------------------------------------------------------------------
ISC SPECIMEN QUESTION PAPER 2025
4
(xii)
Given below are two statements marked Assertion and Reason. Read both the
statements carefully and choose the correct option. (Analysis)
Assertion: E. coli was transformed by inserting the foreign DNA by using PvuI
in pBR322.
Reason: It was done to make the transformed cells survive in the culture medium
containing ampicillin.
[1]
(a) Both Assertion and Reason are true, and Reason is the correct explanation
for Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct
explanation for Assertion.
(c) Assertion is true and Reason is false.
(d) Both Assertion and Reason are false.
(xiii) What is the advantage of growing apomictic seeds in crop improvement?
(Understanding)
[1]
(xiv) A farmer has two fields in which he wants to grow a cereal crop and a legume.
He cannot afford to spend a lot of money on chemical fertilisers to increase the
fertility of the soil.
Suggest a way to help him resolve the issue. (Application)
[1]
(xv) Answer the following questions.
[2]
(a) Expand the abbreviation MALT. (Recall)
(b) David is a molecular biologist. He uses a technique to know the amino
acids occupy the first and the last positions in the Chain – A and
Chain – B of insulin. Name the scientist whose contribution made it
possible for David to use this technique. (Recall)
(xvi) In a flower, the megaspore mother cell formed four megaspores without
undergoing meiosis. One of the four megaspores developed into the embryo sac.
What would be the ploidy level of the antipodal cells in this embryo sac?
(Understanding)
[1]
(xvii) The diagram given below represents a specific stage of human embryonic
development. Identify the stage. (Recall)
[1]
Page 5
----------------------------------------------------------------------------------------------------------------------
ISC SPECIMEN QUESTION PAPER 2025
1
BIOLOGY
PAPER 1
(THEORY)
Maximum Marks: 70
Time Allotted: Three Hours
Reading Time: Additional Fifteen Minutes
Instructions to Candidates
? You are allowed additional fifteen minutes for only reading the question
paper.
? You must NOT start writing during reading time.
? This question paper has 11 printed pages. It has 18 questions in all.
? Answer all questions.
? There are four sections in the paper: A, B, C and D. Internal choices have
been provided in one question each in Sections B, C and D.
? Section A consists of one question each carrying one / two mark(s).
? Section B consists of seven questions each carrying two marks.
? Section C consists of seven questions each carrying three marks.
? Section D consists of three questions each carrying five marks.
? Diagrams should be drawn wherever necessary using a pencil only.
? The intended marks for questions are given in brackets [ ].
Instruction to Supervising Examiner
? Kindly read aloud the Instructions given above to all the candidates present
in the examination hall.
---------------------------------------------------------------------------------------------------------------------
ISC SPECIMEN QUESTION PAPER 2025
2
SECTION A – 20 MARKS
Question 1
Answer the following questions briefly.
(i) Sapna has been diagnosed with an infection of the reproductive tract caused by
bacteria. She experiences burning sensation during urination, pain around her
genitalia and observes pus containing discharge. Her doctor tells her that this
infection has an incubation period of two to five days but can be cured.
What is the biological name of the causative agent of the disease Sapna is suffering
from? (Recall)
[1]
(ii) The number of chromosomes in the leaf cells of a male plant is 40 and in the
stem cells of a female plant is 60. If they are artificially hybridised, what will be
the number of chromosomes in the endosperm? (Application)
[1]
(iii) How many cycles of PCR are required to produce 250 molecules of DNA,
starting with a single parental strand? (Application)
[1]
(iv) Which is the most commonly prescribed non-steroidal oral contraceptive pill in
India? (Recall)
[1]
(v) Tall pea plants having green pods were crossed with dwarf pea plants having
yellow pods. Out of 80 plants, how many are likely to be tall plants in the F2
generation? (Application)
[1]
(vi) Write a 6-nucleotide long palindromic sequence on a double stranded DNA,
which was reverse transcribed by the following nucleotide sequence on a
retroviral RNA. (Create)
3’-GUA- - - 5’
[1]
(vii) In the given figure of mammalian spermatozoon, “X” is an organelle. Identify
the organelle. (Recall)
[1]
---------------------------------------------------------------------------------------------------------------------
ISC SPECIMEN QUESTION PAPER 2025
3
(viii) Observe the relation between the first two words and then fill in the fourth word.
Histamine: Mast cells :: Antibody: ____________ (Analysis)
[1]
(ix) Which of the following sequences of mRNA will NOT translate completely?
(Recall)
[1]
(a) 5' - AUG UUC AGC UCG UGA - 3'
(b) 5'- AUG AAC UAA CCA CUC - 3'
(c) 5' - AUG UUA CUC GCG UAA - 3'
(d) 5' - AUG CCA UAC GAC UAG - 3'
(x) Which one of the following choices reflects the correct number of chromosomes
in the zygote and in the second polar body of Drosophila melanogaster?
[1]
Zygote Meiocytes
I 08 08
II 04 08
III 08 04
IV 04 04
(a) I
(b) II
(c) III
(d) IV
(xi)
Given below are two statements marked Assertion and Reason. Read both the
statements carefully and choose the correct option. (Analysis)
Assertion: Earthworm is called a detritivore.
Reason: It breaks down the water-soluble inorganic nutrients, which percolate
down into the soil.
[1]
(a) Both Assertion and Reason are true and Reason is the correct explanation
for Assertion.
(b) Both Assertion and Reason are true but Reason is not the correct
explanation for Assertion.
(c) Assertion is true and Reason is false.
(d) Both Assertion and Reason are false.
---------------------------------------------------------------------------------------------------------------------
ISC SPECIMEN QUESTION PAPER 2025
4
(xii)
Given below are two statements marked Assertion and Reason. Read both the
statements carefully and choose the correct option. (Analysis)
Assertion: E. coli was transformed by inserting the foreign DNA by using PvuI
in pBR322.
Reason: It was done to make the transformed cells survive in the culture medium
containing ampicillin.
[1]
(a) Both Assertion and Reason are true, and Reason is the correct explanation
for Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct
explanation for Assertion.
(c) Assertion is true and Reason is false.
(d) Both Assertion and Reason are false.
(xiii) What is the advantage of growing apomictic seeds in crop improvement?
(Understanding)
[1]
(xiv) A farmer has two fields in which he wants to grow a cereal crop and a legume.
He cannot afford to spend a lot of money on chemical fertilisers to increase the
fertility of the soil.
Suggest a way to help him resolve the issue. (Application)
[1]
(xv) Answer the following questions.
[2]
(a) Expand the abbreviation MALT. (Recall)
(b) David is a molecular biologist. He uses a technique to know the amino
acids occupy the first and the last positions in the Chain – A and
Chain – B of insulin. Name the scientist whose contribution made it
possible for David to use this technique. (Recall)
(xvi) In a flower, the megaspore mother cell formed four megaspores without
undergoing meiosis. One of the four megaspores developed into the embryo sac.
What would be the ploidy level of the antipodal cells in this embryo sac?
(Understanding)
[1]
(xvii) The diagram given below represents a specific stage of human embryonic
development. Identify the stage. (Recall)
[1]
---------------------------------------------------------------------------------------------------------------------
ISC SPECIMEN QUESTION PAPER 2025
5
(xviii) Give a reason for each of the following. (Analysis) [2]
(a)
The diagram given below represents vector pBr322 which was modified
by a research scholar Dr. Rayon, but the vector was rejected by his guide.
(b) The continuous inbreeding of crops may lead to reduced fertility and
productivity. However, the self-pollinated crops do not show the
ill-effects of inbreeding.
SECTION B – 14 MARKS
Question 2 [2]
(i) During embryogenesis in dicots, the zygote divides into a basal cell and a terminal
cell. The basal cell divides repeatedly to produce a structure called suspensor.
Carefully observe the image given below and describe the function of cell – A
and cell – B of the suspensor. (Understanding)
OR
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