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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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FAQs on ICSE Biology Sample Paper with Solution - 2025 - ICSE Class 12 Science Sample Papers

1. What are the key topics covered in the ICSE Class 12 Biology syllabus?
Ans. The ICSE Class 12 Biology syllabus typically includes key topics such as Genetics, Human Physiology, Plant Physiology, Ecology, and Biotechnology. Students study the structure and function of different biological systems, the principles of inheritance, the processes of photosynthesis and respiration in plants, and the interaction of organisms with their environment.
2. How can students effectively prepare for the ICSE Class 12 Biology exam?
Ans. Students can effectively prepare for the ICSE Class 12 Biology exam by creating a structured study plan that includes regular review of key concepts, practicing past exam papers, and taking mock tests. Engaging in group study sessions, utilizing diagrams and flowcharts for visual learning, and seeking clarification on difficult topics can also enhance understanding and retention.
3. What types of questions can be expected in the ICSE Class 12 Biology exam?
Ans. The ICSE Class 12 Biology exam typically features a variety of question types, including multiple-choice questions, short answer questions, and long answer questions. Questions may cover definitions, explanations of processes, diagrams, and applications of biological concepts in real-world scenarios, encouraging critical thinking and application of knowledge.
4. What is the importance of practicals in the ICSE Class 12 Biology curriculum?
Ans. Practicals in the ICSE Class 12 Biology curriculum are crucial as they provide hands-on experience in scientific techniques and methodologies. They help students to understand theoretical concepts through observation and experimentation, develop analytical skills, and enhance their ability to work in a lab environment, which is essential for future studies or careers in biological sciences.
5. How is the marking scheme structured for the ICSE Class 12 Biology exam?
Ans. The marking scheme for the ICSE Class 12 Biology exam is generally structured to reward students for clarity, accuracy, and depth of understanding. Marks are typically allocated for correct answers, logical presentation of information, and the inclusion of diagrams where applicable. Additionally, marks may be awarded for the application of knowledge to solve problems or interpret data, ensuring that students demonstrate comprehensive learning.
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