CBSE Class 12 Biology Set 3 - (57/5/3) Question Paper 2026 is available for download here. CBSE conducted Class 12 Biology exam on March 27, 2026 from 10:30 AM to 1:30 PM. The Biology theory paper is of 70 marks, and the internal assessment is of 30 marks.
Also Check: CBSE Class 12 Question Paper 2026 (All Subjects)
The Biology question paper includes the following types of questions, which make up the total of 70 marks:
- MCQs: 1 mark each
- Short-answer type questions: 2 & 3 marks each
- Case-study based questions: 4 marks each
- Long-answer type questions: 5 marks each
CBSE Class 12 Biology Question Paper 2026 (Set 3 - 57/5/3) with Solution PDF
| CBSE Official PDF | CD PDF | CD PDF with Solutions |
|---|---|---|
| Download official PDF 0.66 MB | Download Collegedunia PDF 0.38 MB | Download solutions PDF 0.48 MB |
CBSE Class 12 Biology 2026 Set 3 (57/5/3) Questions with Solutions
The foetal ejection reflex in human triggers the release of _______ hormone from _______
Match the IUDs in Column I with suitable example in Column II.
| Column I | Column II |
|---|---|
| a. Non-medicated | i. Lippes loop |
| b. Copper releasing | ii. LNG-20 |
| c. Hormone releasing | iii. Multiload 375 |
In Pisum sativum, the flower colour may be violet (V) or white (v). What proportion of the offspring in a cross of "VV × vv" would be expected to be violet?
Arrange the following in the correct sequence of their evolution and select the correct option:
(i) Seaweed
(ii) Invertebrates
(iii) Jawless fish
If a genetic disease is transferred from a phenotypically normal but carrier female to only some of the male progeny, the disease is :
A DNA molecule is 160 base pairs long. It has 30% Guanine. How many Adenine bases are present in this DNA molecule?
A doctor identifies symptoms of nasal congestion, headache, sore throat, hoarseness and cough in a patient. The conclusion is that the patient is infected by a pathogen :
Which type of selection is industrial melanism observed in moth, Biston betularia ?
Given below is the restriction site of a restriction endonuclease Pst I and the cleavage sites on a DNA molecule.
Which of the following fish led to the extinction of an ecologically unique assemblage of more than 200 species of cichlid fish in Lake Victoria of East Africa?
Cattle or goats are never seen browsing on the weed, Calotropis. Select the correct option for the reason.
Assertion (A): Repetitive sequences make up a very large portion of human genome.
Reason (R): Repetitive sequences do not have direct coding functions in the genome.
Assertion (A): The embryo with 8 to 16 blastomeres is called a morula.
Reason (R): The morula continues to divide and transform into trophoblast.
Assertion (A): The use of chitinase enzyme is necessary for the separation of DNA from yeast cells but not in the case of Spirogyra.
Reason (R): Fungal cell wall is made up of fungal chitin.
Assertion (A) : Besides curdling of milk, LAB also improves its nutritional quality by increasing Vitamin B12.
Reason (R) : LAB, when present in the stomach checks disease-causing microbes.
State the role of thymus as a lymphoid organ. Name the cells that are released from it and mention their functions.
Explain the mutually rewarding relationship between Yucca plant and species of moth.
Pollination success will be reduced unless the orchid flower co-evolves with the pollinator. Explain.
Differentiate between grazing food chain and detritus food chain.
Ecological pyramids are widely accepted but they still have some limitations. Write any two limitations.
How do ‘implants’ act as an effective method of contraception in human females ? Mention one advantage of implants over contraceptive pills.
Name the most commonly used bioreactor. List the advantages of the bioreactor. Also write the importance of sampling ports.
Draw a labelled diagram of a 'replicating fork' showing the polarity. Why does DNA replication occur within such 'fork'?
List any three outbreeding devices that flowering plants have developed for cross-pollination and explain how they help to encourage cross-pollination.
Explain how the following microbes act as biocontrol agents :
(a) Bacillus thuringiensis
(b) Nucleopolyhedrovirus
Transgenic animals are produced by man. Explain any three ways in which such animals can be beneficial to humans.
Explain the level of biodiversity at genetic, species, and ecological levels with the help of one example each.
Study the given chart showing the evolution of plants. Answer the following questions:
(b) Name the nearest ancestors of flowering plants.
(c) Name the most primitive group of plants.
(d) Psilophyton provides common ancestry to which classes?
(e) Name the common ancestor of Psilophyton and seed ferns.
(f) Name the common ancestor of mosses and tracheophytes.
Given below is an equation describing the growth pattern of a population :
\( \dfrac{dN}{dt} = rN \)
(a) Mention the type of growth model or growth pattern of the population described by the given equation.
(b) What does r in the equation signify ?
(c) Mention the type of growth curve that will be obtained if the population density (N) is plotted against time (t).
(d) According to you, will the resource availability be limited or unlimited for this type of growth in the given population ?
Read the following passage and answer the questions that follow:
The process of copying genetic information from template strand of DNA into RNA is called transcription. It is mediated by RNA polymerase. Transcription takes place in the nucleus of eukaryotic cells. In transcription, only a segment of DNA and only one of the strands is copied into RNA.
Read the following passage and answer the questions that follow :
The process of copying genetic information from template strand of DNA into RNA is called transcription. It is mediated by RNA polymerase. Transcription takes place in the nucleus of eukaryotic cells. In transcription, only a segment of DNA and only one of the strands is copied into RNA.
(a) Why is the strand of DNA with \( 3^{\prime} \rightarrow 5^{\prime} \) polarity transcribed and not the other strand of \( 5^{\prime} \rightarrow 3^{\prime} \) polarity ?
Read the following passage and answer the questions that follow :
The process of copying genetic information from template strand of DNA into RNA is called transcription. It is mediated by RNA polymerase. Transcription takes place in the nucleus of eukaryotic cells. In transcription, only a segment of DNA and only one of the strands is copied into RNA.
(b) (i) Why is hnRNA required to undergo splicing ?
Read the following passage and answer the questions that follow :
The process of copying genetic information from template strand of DNA into RNA is called transcription. It is mediated by RNA polymerase. Transcription takes place in the nucleus of eukaryotic cells. In transcription, only a segment of DNA and only one of the strands is copied into RNA.
(b) (ii) Mention the two additional processes which hnRNA needs to undergo after splicing to become functional.
Read the following passage and answer the questions that follow :
The process of copying genetic information from template strand of DNA into RNA is called transcription. It is mediated by RNA polymerase. Transcription takes place in the nucleus of eukaryotic cells. In transcription, only a segment of DNA and only one of the strands is copied into RNA.
(c) Why is only one strand of the DNA transcribed ? Give two reasons.
Read the following passage and answer the questions that follow:
We know that plasmids and bacteriophages are the most commonly used vectors in biotechnology experiments. If we can link an alien piece of DNA to the plasmid DNA, the alien DNA can be multiplied equal to the copy number of the plasmid. Engineered vectors are used these days. Study the diagram of the E. coli cloning vector pBR322 and answer the questions that follow:
Read the following passage and answer the questions that follow :
We know that plasmids and bacteriophages are the most commonly used vectors in biotechnology experiments. If we can link an alien piece of DNA to the plasmid DNA, the alien DNA can be multiplied equal to the copy number of the plasmid. Engineered vectors are used these days. Study the diagram of the E. coli cloning vector pBR322 and answer the questions that follow :
(a) Why are plasmids and bacteriophages used as cloning vectors ?
Read the following passage and answer the questions that follow :
We know that plasmids and bacteriophages are the most commonly used vectors in biotechnology experiments. If we can link an alien piece of DNA to the plasmid DNA, the alien DNA can be multiplied equal to the copy number of the plasmid. Engineered vectors are used these days. Study the diagram of the E. coli cloning vector pBR322 and answer the questions that follow :
(b) (i) Identify :
(I) The gene in the cloning vector that controls the copy number of the vector.
(II) The restriction site - C in the "rop" gene.
Read the following passage and answer the questions that follow :
We know that plasmids and bacteriophages are the most commonly used vectors in biotechnology experiments. If we can link an alien piece of DNA to the plasmid DNA, the alien DNA can be multiplied equal to the copy number of the plasmid. Engineered vectors are used these days. Study the diagram of the E. coli cloning vector pBR322 and answer the questions that follow :
(b) (ii) Identify and name two selectable markers shown in the diagram.
Read the following passage and answer the questions that follow :
We know that plasmids and bacteriophages are the most commonly used vectors in biotechnology experiments. If we can link an alien piece of DNA to the plasmid DNA, the alien DNA can be multiplied equal to the copy number of the plasmid. Engineered vectors are used these days. Study the diagram of the E. coli cloning vector pBR322 and answer the questions that follow :
(c) Name the two restriction sites each in the two genes you have identified as selectable markers.
Work out separate monohybrid crosses up to \(F_2\) generation between two pea plants and two Antirrhinum plants, both having contrasting traits with respect to the colour of the flower. Comment on the patterns of inheritance in the crosses carried out in such two cases.
Name the phenomenon that leads to situations like ‘XO’ abnormality in humans. Also name this genetic disorder. How are individuals with an XO chromosomal abnormality affected ? Write its symptoms as well as karyotype.
How does a chromosomal disorder differ from a Mendelian disorder ? Write one example for each.
Mention the source and the role of the following in providing defence against infection in the human body : (I) Histamine (II) Interferons
(I) Write the scientific names of the two species of filarial worms causing filariasis.
(II) How do they affect the body of infected persons ?
(III) How does the disease spread ?
Draw the structure of an antibody molecule and label any four of its parts.
Differentiate between active and passive immunity. Write any three differences.
Arrange the following hormones in sequence of their secretion in a pregnant woman : hCG; LH; FSH; Relaxin.
Mention the source and the functions of the above mentioned hormones.
Briefly explain the events of fertilisation and implantation in an adult human female.
CBSE Class 12 Biology Question Paper Pattern and Marking Scheme
The CBSE Class 12 Biology 2026 question paper is of 70 marks and has 33 questions in five sections, A to E, all compulsory. The tables below give the section-wise paper pattern and the marking rules from the official CBSE marking scheme.
CBSE Class 12 Biology Question Paper Pattern 2026
| Section | Questions | Question Type | Marks per Question | Marks |
|---|---|---|---|---|
| A | Q1 - Q16 | Multiple choice questions | 1 | 16 |
| B | Q17 - Q21 | Very short answer type | 2 | 10 |
| C | Q22 - Q28 | Short answer type | 3 | 21 |
| D | Q29 - Q30 | Case-based questions | 4 | 8 |
| E | Q31 - Q33 | Long answer type | 5 | 15 |
| Total | 33 questions | 70 |
CBSE Class 12 Biology Marking Scheme 2026
| Marking point | How it is applied |
|---|---|
| Value-point marking | Marks are awarded against the value points (steps) given in the official marking scheme; the marks of an answer are split across its steps. |
| Own expression | The marking scheme carries suggested value points only. A correct answer in the student's own words is awarded due marks. |
| Competency-based questions | If a competency-based answer is not from the marking scheme but shows the correct competency, due marks are awarded. |
| Errors | An error is penalised only once; no marks are deducted for its cumulative effect. |
| Incorrect answer | A totally incorrect answer is awarded zero (0) marks. |
| Choice (OR) questions | If both options of a question with internal choice are attempted, marks are awarded for both and the higher score is taken; if only one option is attempted, the other is marked NA (not attempted). |
| Scale of marks | The full scale of 0 to 70 marks is used and full marks are awarded whenever the answer deserves them. |
CBSE Class 12 Biology Unit-Wise Weightage
| Unit No. | Unit Name | Marks |
|---|---|---|
| VI | Reproduction | 16 |
| VII | Genetics and Evolution | 20 |
| VIII | Biology and Human Welfare | 12 |
| IX | Biotechnology and Its Applications | 12 |
| X | Ecology and Environment | 10 |
| Total | — | 70 |
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